s-adenosyl-l-methionine arseniciii methyltransferase: Topics by WorldWideScience.org

Sample records for s-adenosyl-l-methionine arseniciii methyltransferase

A NOVEL S-ADENOSYL-L-METHIONINE: ARSENIC (III) METHYLTRANSFERASE FROM RAT LIVER CYTOSOL

Science.gov (United States)

A Novel S-Adenosyl-L-methionine: Arsenic(III) Methyltransferase from Rat Liver CytosolShan Lin, Qing Shi, F. Brent Nix, Miroslav Styblo, Melinda A. Beck, Karen M. Herbin-Davis, Larry L. Hall, Josef B. Simeonsson, and David J. Thomas S-adenosyl-L-methionine (AdoMet): ar...
CLONING, EXPRESSION, AND CHARACTERIZATION OF RAT S-ADENOSYL-L-METHIONINE: ARSENIC (III) METHYLTRANSFERASE (CYT19)

Science.gov (United States)

CLONING, EXPRESSION, AND CHARACTERIZATION OF RAT S-ADENOSYL-L-METHIONINE: ARSENIC(III) METHYLTRANSFERASE (cyt19)Stephen B. Waters1 , Felicia Walton1 , Miroslav Styblo1 , Karen Herbin-Davis2, and David J. Thomas2 1 School of Medicine, University of North Carolina at Chape...
CLONING, EXPRESSION, AND MUTATIONAL ANALYSIS OF RAT S-ADENOSYL-1-METHIONINE: ARSENIC (III) METHYLTRANSFERASE

Science.gov (United States)

CLONING, EXPRESSION, AND MUTATIONAL ANALYSIS OF RAT S-ADENOSYL-L-METHIONINE: ARSENIC(III) METHYLTRANSFERASEStephen B. Waters, Ph.D., Miroslav Styblo, Ph.D., Melinda A. Beck, Ph.D., University of North Carolina at Chapel Hill; David J. Thomas, Ph.D., U.S. Environmental...
Crystallization of the novel S-adenosyl-l-methionine-dependent C-methyltransferase CouO from Streptomyces rishiriensis and preliminary diffraction data analysis

International Nuclear Information System (INIS)

Lyskowski, Andrzej; Tengg, Martin; Steinkellner, Georg; Schwab, Helmut; Gruber-Khadjawi, Mandana; Gruber, Karl

2012-01-01

Recombinant Q9F8T9 protein from Streptomyces rishiriensis (CouO), an S-adenosyl-l-methionine-dependent C-methyltransferase, has been successfully cloned, expressed and purified. Recombinant Q9F8T9 protein from Streptomyces rishiriensis (CouO), an S-adenosyl-l-methionine-dependent C-methyltransferase, has been successfully cloned, expressed and purified. CouO was crystallized from a single condition in the Morpheus crystallization screen. A vitrified crystal diffracted to 2.05 Å resolution and belonged to space group P2 1 , with unit-cell parameters a = 33.02, b = 82.87, c = 76.77 Å, β = 96.93°
S-Inosyl-L-Homocysteine Hydrolase, a Novel Enzyme Involved in S-Adenosyl-L-Methionine Recycling.

Science.gov (United States)

Miller, Danielle; Xu, Huimin; White, Robert H

2015-07-01

S-Adenosyl-L-homocysteine, the product of S-adenosyl-L-methionine (SAM) methyltransferases, is known to be a strong feedback inhibitor of these enzymes. A hydrolase specific for S-adenosyl-L-homocysteine produces L-homocysteine, which is remethylated to methionine and can be used to regenerate SAM. Here, we show that the annotated S-adenosyl-L-homocysteine hydrolase in Methanocaldococcus jannaschii is specific for the hydrolysis and synthesis of S-inosyl-L-homocysteine, not S-adenosyl-L-homocysteine. This is the first report of an enzyme specific for S-inosyl-L-homocysteine. As with S-adenosyl-L-homocysteine hydrolase, which shares greater than 45% sequence identity with the M. jannaschii homologue, the M. jannaschii enzyme was found to copurify with bound NAD(+) and has Km values of 0.64 ± 0.4 mM, 0.0054 ± 0.006 mM, and 0.22 ± 0.11 mM for inosine, L-homocysteine, and S-inosyl-L-homocysteine, respectively. No enzymatic activity was detected with S-adenosyl-L-homocysteine as the substrate in either the synthesis or hydrolysis direction. These results prompted us to redesignate the M. jannaschii enzyme an S-inosyl-L-homocysteine hydrolase (SIHH). Identification of SIHH demonstrates a modified pathway in this methanogen for the regeneration of SAM from S-adenosyl-L-homocysteine that uses the deamination of S-adenosyl-L-homocysteine to form S-inosyl-L-homocysteine. In strictly anaerobic methanogenic archaea, such as Methanocaldococcus jannaschii, canonical metabolic pathways are often not present, and instead, unique pathways that are deeply rooted on the phylogenetic tree are utilized by the organisms. Here, we discuss the recycling pathway for S-adenosyl-L-homocysteine, produced from S-adenosyl-L-methionine (SAM)-dependent methylation reactions, which uses a hydrolase specific for S-inosyl-L-homocysteine, an uncommon metabolite. Identification of the pathways and the enzymes involved in the unique pathways in the methanogens will provide insight into the
Growth inhibition of Chromatium D by L-methionine and its correlation to unusual accumulation of S-adenosyl-L-methionine in the cell

Energy Technology Data Exchange (ETDEWEB)

Sugimoto, Y; Nakatani, K; Shirakashi, T; Ohmori, H; Toraya, T [Kyoto Univ. (Japan). Faculty of Engineering

1976-07-01

L-Methionine strongly inhibited the growth of Chromatium D when added at a low concentration to the growth medium containing both sulfide and thiosulfate. S-Adenosyl-L-methionine inhibited the growth, irrespective of the coexistence of sulfide and thiosulfate. Upon addition of L-methionine to the growth media, the presence of both sulfide and thiosulfate in the media stimulated the in vivo conversion of L-methionine to S-adenosyl-L-methionine, and consequently increased the intracellular level of S-adenosyl-L-methionine. From these data, it was strongly suggested that the unusual accumulation of S-adenosyl-L-methionine in the cells of Chromatium D is responsible for the growth inhibition by L-methionine. The level of S-adenosyl-L-methionine synthetase (ATP: L-methionine S-adenosyltransferase, EC2.5.16) was significantly enhanced by adding L-methionine, sulfide and thiosulfate to the growth medium.
S-adenosyl-L-methionine for alcoholic liver diseases

DEFF Research Database (Denmark)

Rambaldi, A; Gluud, C

2006-01-01

Alcohol is a major cause of liver disease and disrupts methionine and oxidative balances. S-adenosyl-L-methionine (SAMe) acts as a methyl donor for methylation reactions and participates in the synthesis of glutathione, the main cellular antioxidant. Randomised clinical trials have addressed...... the question whether SAMe may benefit patients with alcoholic liver diseases....
S-adenosyl-L-methionine for alcoholic liver diseases

DEFF Research Database (Denmark)

Rambaldi, A; Gluud, C

2001-01-01

Alcohol is a major cause of liver disease in the Western world today. S-adenosyl-L-methionine (SAMe) acts as a methyl donor for all known biological methylation reactions and participates in the synthesis of glutathione, the main cellular anti-oxidant. Randomised clinical trials have addressed...... the question whether SAMe has any efficacy in patients with alcoholic liver diseases....
Structures of a putative RNA 5-methyluridine methyltransferase, Thermus thermophilus TTHA1280, and its complex with S-adenosyl-l-homocysteine

International Nuclear Information System (INIS)

Pioszak, Augen A.; Murayama, Kazutaka; Nakagawa, Noriko; Ebihara, Akio; Kuramitsu, Seiki; Shirouzu, Mikako; Yokoyama, Shigeyuki

2005-01-01

Three structures of a putative RNA 5-methyluridine methyltransferase from T. thermophilus, including its complex with S-adenosyl-l-homocysteine, are presented. The structures reveal the mode of cofactor binding, architecture of the putative active site, and the presence of a deep cleft adjacent to the active site that may bind RNA. The Thermus thermophilus hypothetical protein TTHA1280 belongs to a family of predicted S-adenosyl-l-methionine (AdoMet) dependent RNA methyltransferases (MTases) present in many bacterial and archaeal species. Inspection of amino-acid sequence motifs common to class I Rossmann-fold-like MTases suggested a specific role as an RNA 5-methyluridine MTase. Selenomethionine (SeMet) labelled and native versions of the protein were expressed, purified and crystallized. Two crystal forms of the SeMet-labelled apoprotein were obtained: SeMet-ApoI and SeMet-ApoII. Cocrystallization of the native protein with S-adenosyl-l-homocysteine (AdoHcy) yielded a third crystal form, Native-AdoHcy. The SeMet-ApoI structure was solved by the multiple anomalous dispersion method and refined at 2.55 Å resolution. The SeMet-ApoII and Native-AdoHcy structures were solved by molecular replacement and refined at 1.80 and 2.60 Å, respectively. TTHA1280 formed a homodimer in the crystals and in solution. Each subunit folds into a three-domain structure composed of a small N-terminal PUA domain, a central α/β-domain and a C-terminal Rossmann-fold-like MTase domain. The three domains form an overall clamp-like shape, with the putative active site facing a deep cleft. The architecture of the active site is consistent with specific recognition of uridine and catalysis of methyl transfer to the 5-carbon position. The cleft is suitable in size and charge distribution for binding single-stranded RNA.
Optimization of L: -methionine feeding strategy for improving S-adenosyl-L: -methionine production by methionine adenosyltransferase overexpressed Pichia pastoris.

Science.gov (United States)

Hu, Hui; Qian, Jiangchao; Chu, Ju; Wang, Yonghong; Zhuang, Yingping; Zhang, Siliang

2009-07-01

The recombinant Pichia pastoris harboring an improved methionine adenosyltransferase (MAT) shuffled gene was employed to biosynthesize S-adenosyl-L: -methionine (SAM). Two L: -methionine (L: -Met) addition strategies were used to supply the precursor: the batch addition strategy (L: -Met was added separately at three time points) and the continuous feeding strategies (L: -Met was fed continuously at the rate of 0.1, 0.2, and 0.5 g l(-1) h(-1), respectively). SAM accumulation, L: -Met conversion rate, and SAM productivity with the continuous feeding strategies were all improved over the batch addition strategy, which reached 8.46 +/- 0.31 g l(-1), 41.7 +/- 1.4%, and 0.18 +/- 0.01 g l(-1) h(-1) with the best continuous feeding strategy (0.2 g l(-1) h(-1)), respectively. The bottleneck for SAM production with the low L: -Met feeding rate (0.1 g L(-1) h(-1)) was the insufficient L: -Met supply. The analysis of the key enzyme activities indicated that the tricarboxylic acid cycle and glycolytic pathway were reduced with the increasing L: -Met feeding rate, which decreased the adenosine triphosphate (ATP) synthesis. The MAT activity also decreased as the L: -Met feeding rate rose. The reduced ATP synthesis and MAT activity were probably the reason for the low SAM accumulation when the L: -Met feeding rate reached 0.5 g l(-1) h(-1).
S-adenosyl-L-(l-14C)-homocysteine

International Nuclear Information System (INIS)

Thomas, H.J.; Montgomery, J.A.

1987-01-01

S-Adenosyl-L-(1- 14 C)-homocysteine was prepared from commercially available L-(1- 14 C)-methionine by conversion first to S-benzyl-L-(1- 14 C)-homocysteine which upon treatment with sodium in liquid ammonia gave the disodium salt of L-(1- 14 C)-homocysteine. Reaction of this sodium salt with 5'-O-tosyladenosine gave the title compound. (author)
Double-blind, placebo-controlled cross-over study of intravenous S-adenosyl-L-methionine in patients with fibromyalgia

DEFF Research Database (Denmark)

Volkmann, H; Nørregaard, J; Jacobsen, Søren

1997-01-01

The objective of this study was to test the efficacy of intravenously administered S-adenosyl-L-methionine (SAMe) in patients with fibromyalgia (FM). Thirty-four out-patients with fibromyalgia symptoms received SAMe 600 mg i.v. or placebo daily for 10 days in a cross-over trial. There was no sign......The objective of this study was to test the efficacy of intravenously administered S-adenosyl-L-methionine (SAMe) in patients with fibromyalgia (FM). Thirty-four out-patients with fibromyalgia symptoms received SAMe 600 mg i.v. or placebo daily for 10 days in a cross-over trial.......17) and slight improvement only on fatigue, quality of sleep, morning stiffness, and on the Fibromyalgia Impact Questionnaire for pain. No effect could be observed on isokinetic muscle strength, Zerrsen self-assessment questionnaire, and the face scale. No effect of SAMe in patients with FM was found...
Identification of a highly conserved domain in the EcoRII methyltransferase which can be photolabeled with S-adenosyl-L-[methyl-3H]methionine. Evidence for UV-induced transmethylation of cysteine 186

International Nuclear Information System (INIS)

Som, S.; Friedman, S.

1991-01-01

DNA methyltransferases can be photolabeled with S-adenosyl-L-methionine (AdoMet). Specific incorporation of radioactivity has been demonstrated after photolabeling with either [methyl-3H]AdoMet or [35S]AdoMet. The labeling is believed to occur at the AdoMet binding site. With the purpose of localizing the site responsible for [methyl-3H]AdoMet photolabeling, we cleaved the labeled EcoRII methyltransferase by chemical and enzymatic reactions and isolated the radiolabeled peptides by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high pressure liquid chromatography. The labeled peptides were identified by amino-terminal sequencing. A common region was localized which accounted for 65-70% of the total label. This region includes a highly conserved core sequence present in all DNA (cytosine 5)-methyltransferases. One such fragment was digested further with chymotrypsin, and amino acid analysis of the resulting 3H-labeled peptide was consistent with the sequence Ala-Gly-Phe-Pro-(Cys)-Gln-Pro-Phe-Ser-Leu. However, the cysteine residue was not recovered as carboxymethylcysteine. The Pro-Cys bond was found to be protected from cleavage at cysteine residues after cyanylation. These results suggest that the cysteine residue is modified by the labeling reaction. The chymotryptic fragment was hydrolyzed enzymatically to single amino acids, and the labeled amino acid was identified as S-methylcysteine by thin layer chromatography. These results indicate that the cysteine residue is located at or close to the AdoMet binding site of EcoRII methyltransferase
The [4Fe-4S](2+) cluster in reconstituted biotin synthase binds S-adenosyl-L-methionine.

Science.gov (United States)

Cosper, Michele Mader; Jameson, Guy N L; Davydov, Roman; Eidsness, Marly K; Hoffman, Brian M; Huynh, Boi Hanh; Johnson, Michael K

2002-11-27

The combination of resonance Raman, electron paramagnetic resonance and Mössbauer spectroscopies has been used to investigate the effect of S-adenosyl-l-methionine (SAM) on the spectroscopic properties of the [4Fe-4S]2+ cluster in biotin synthase. The results indicate that SAM interacts directly at a unique iron site of the [4Fe-4S]2+ cluster in BioB and support the hypothesis of a common inner-sphere mechanism for the reductive cleavage of SAM in the radical SAM family of Fe-S enzymes.
Crystal Structure of the Thermus thermophilus 16 S rRNA Methyltransferase RsmC in Complex with Cofactor and Substrate Guanosine

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Demirci, H.; Gregory, S; Dahlberg, A; Jogl, G

2008-01-01

Post-transcriptional modification is a ubiquitous feature of ribosomal RNA in all kingdoms of life. Modified nucleotides are generally clustered in functionally important regions of the ribosome, but the functional contribution to protein synthesis is not well understood. Here we describe high resolution crystal structures for the N{sup 2}-guanine methyltransferase RsmC that modifies residue G1207 in 16 S rRNA near the decoding site of the 30 S ribosomal subunit. RsmC is a class I S-adenosyl-l-methionine-dependent methyltransferase composed of two methyltransferase domains. However, only one S-adenosyl-l-methionine molecule and one substrate molecule, guanosine, bind in the ternary complex. The N-terminal domain does not bind any cofactor. Two structures with bound S-adenosyl-l-methionine and S-adenosyl-l-homocysteine confirm that the cofactor binding mode is highly similar to other class I methyltransferases. Secondary structure elements of the N-terminal domain contribute to cofactor-binding interactions and restrict access to the cofactor-binding site. The orientation of guanosine in the active site reveals that G1207 has to disengage from its Watson-Crick base pairing interaction with C1051 in the 16 S rRNA and flip out into the active site prior to its modification. Inspection of the 30 S crystal structure indicates that access to G1207 by RsmC is incompatible with the native subunit structure, consistent with previous suggestions that this enzyme recognizes a subunit assembly intermediate.
Modification of S-Adenosyl-l-Homocysteine as Inhibitor of Nonstructural Protein 5 Methyltransferase Dengue Virus Through Molecular Docking and Molecular Dynamics Simulation.

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Tambunan, Usman Sumo Friend; Nasution, Mochammad Arfin Fardiansyah; Azhima, Fauziah; Parikesit, Arli Aditya; Toepak, Erwin Prasetya; Idrus, Syarifuddin; Kerami, Djati

2017-01-01

Dengue fever is still a major threat worldwide, approximately threatening two-fifths of the world's population in tropical and subtropical countries. Nonstructural protein 5 (NS5) methyltransferase enzyme plays a vital role in the process of messenger RNA capping of dengue by transferring methyl groups from S -adenosyl-l-methionine to N7 atom of the guanine bases of RNA and the RNA ribose group of 2'OH, resulting in S -adenosyl-l-homocysteine (SAH). The modification of SAH compound was screened using molecular docking and molecular dynamics simulation, along with computational ADME-Tox (absorption, distribution, metabolism, excretion, and toxicity) test. The 2 simulations were performed using Molecular Operating Environment (MOE) 2008.10 software, whereas the ADME-Tox test was performed using various software. The modification of SAH compound was done using several functional groups that possess different polarities and properties, resulting in 3460 ligands to be docked. After conducting docking simulation, we earned 3 best ligands (SAH-M331, SAH-M2696, and SAH-M1356) based on ΔG binding and molecular interactions, which show better results than the standard ligands. Moreover, the results of molecular dynamics simulation show that the best ligands are still able to maintain the active site residue interaction with the binding site until the end of the simulation. After a series of molecular docking and molecular dynamics simulation were performed, we concluded that SAH-M1356 ligand is the most potential SAH-based compound to inhibit NS5 methyltransferase enzyme for treating dengue fever.
S-Adenosyl-S-carboxymethyl-l-homocysteine: a novel cofactor found in the putative tRNA-modifying enzyme CmoA

International Nuclear Information System (INIS)

Byrne, Robert T.; Whelan, Fiona; Aller, Pierre; Bird, Louise E.; Dowle, Adam; Lobley, Carina M. C.; Reddivari, Yamini; Nettleship, Joanne E.; Owens, Raymond J.; Antson, Alfred A.; Waterman, David G.

2013-01-01

The putative methyltransferase CmoA is involved in the nucleoside modification of transfer RNA. X-ray crystallography and mass spectrometry are used to show that it contains a novel SAM derivative, S-adenosyl-S-carboxymethyl-l-homocysteine, in which the donor methyl group is replaced by a carboxymethyl group. Uridine at position 34 of bacterial transfer RNAs is commonly modified to uridine-5-oxyacetic acid (cmo 5 U) to increase the decoding capacity. The protein CmoA is involved in the formation of cmo 5 U and was annotated as an S-adenosyl-l-methionine-dependent (SAM-dependent) methyltransferase on the basis of its sequence homology to other SAM-containing enzymes. However, both the crystal structure of Escherichia coli CmoA at 1.73 Å resolution and mass spectrometry demonstrate that it contains a novel cofactor, S-adenosyl-S-carboxymethyl-l-homocysteine (SCM-SAH), in which the donor methyl group is substituted by a carboxymethyl group. The carboxyl moiety forms a salt-bridge interaction with Arg199 that is conserved in a large group of CmoA-related proteins but is not conserved in other SAM-containing enzymes. This raises the possibility that a number of enzymes that have previously been annotated as SAM-dependent are in fact SCM-SAH-dependent. Indeed, inspection of electron density for one such enzyme with known X-ray structure, PDB entry http://scripts.iucr.org/cgi-bin/cr.cgi?rm, suggests that the active site contains SCM-SAH and not SAM
Double-blind, placebo-controlled cross-over study of intravenous S-adenosyl-L-methionine in patients with fibromyalgia

DEFF Research Database (Denmark)

Volkmann, H; Nørregaard, J; Jacobsen, Søren

1997-01-01

The objective of this study was to test the efficacy of intravenously administered S-adenosyl-L-methionine (SAMe) in patients with fibromyalgia (FM). Thirty-four out-patients with fibromyalgia symptoms received SAMe 600 mg i.v. or placebo daily for 10 days in a cross-over trial. There was no sign......The objective of this study was to test the efficacy of intravenously administered S-adenosyl-L-methionine (SAMe) in patients with fibromyalgia (FM). Thirty-four out-patients with fibromyalgia symptoms received SAMe 600 mg i.v. or placebo daily for 10 days in a cross-over trial....... There was no significant difference in improvement in the primary outcome: tender point change between the two treatment groups. There was a tendency towards statistical significance in favour of SAMe on subjective perception of pain at rest (p = 0.08), pain on movement (p = 0.11), and overall well-being (p = 0.......17) and slight improvement only on fatigue, quality of sleep, morning stiffness, and on the Fibromyalgia Impact Questionnaire for pain. No effect could be observed on isokinetic muscle strength, Zerrsen self-assessment questionnaire, and the face scale. No effect of SAMe in patients with FM was found...
S-Adenosyl-S-carboxymethyl-l-homocysteine: a novel cofactor found in the putative tRNA-modifying enzyme CmoA

Energy Technology Data Exchange (ETDEWEB)

Byrne, Robert T.; Whelan, Fiona [University of York, Heslington YO10 5DD (United Kingdom); Aller, Pierre [Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Bird, Louise E. [OPPF-UK, Research Complex at Harwell, R92 Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom); Oxford University, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Dowle, Adam [University of York, Heslington YO10 5DD (United Kingdom); Lobley, Carina M. C. [Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Reddivari, Yamini; Nettleship, Joanne E.; Owens, Raymond J. [OPPF-UK, Research Complex at Harwell, R92 Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom); Oxford University, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Antson, Alfred A. [University of York, Heslington YO10 5DD (United Kingdom); Waterman, David G., E-mail: david.waterman@stfc.ac.uk [STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom); University of York, Heslington YO10 5DD (United Kingdom)

2013-06-01

The putative methyltransferase CmoA is involved in the nucleoside modification of transfer RNA. X-ray crystallography and mass spectrometry are used to show that it contains a novel SAM derivative, S-adenosyl-S-carboxymethyl-l-homocysteine, in which the donor methyl group is replaced by a carboxymethyl group. Uridine at position 34 of bacterial transfer RNAs is commonly modified to uridine-5-oxyacetic acid (cmo{sup 5}U) to increase the decoding capacity. The protein CmoA is involved in the formation of cmo{sup 5}U and was annotated as an S-adenosyl-l-methionine-dependent (SAM-dependent) methyltransferase on the basis of its sequence homology to other SAM-containing enzymes. However, both the crystal structure of Escherichia coli CmoA at 1.73 Å resolution and mass spectrometry demonstrate that it contains a novel cofactor, S-adenosyl-S-carboxymethyl-l-homocysteine (SCM-SAH), in which the donor methyl group is substituted by a carboxymethyl group. The carboxyl moiety forms a salt-bridge interaction with Arg199 that is conserved in a large group of CmoA-related proteins but is not conserved in other SAM-containing enzymes. This raises the possibility that a number of enzymes that have previously been annotated as SAM-dependent are in fact SCM-SAH-dependent. Indeed, inspection of electron density for one such enzyme with known X-ray structure, PDB entry http://scripts.iucr.org/cgi-bin/cr.cgi?rm, suggests that the active site contains SCM-SAH and not SAM.
Treatment of Creatine Transporter (SLC6A8) Deficiency With Oral S-Adenosyl Methionine as Adjunct to L-arginine, Glycine, and Creatine Supplements.

Science.gov (United States)

Jaggumantri, Sravan; Dunbar, Mary; Edgar, Vanessa; Mignone, Cristina; Newlove, Theresa; Elango, Rajavel; Collet, Jean Paul; Sargent, Michael; Stockler-Ipsiroglu, Sylvia; van Karnebeek, Clara D M

2015-10-01

Creatine transporter (SLC6A8) deficiency is an X-linked inborn error of metabolism characterized by cerebral creatine deficiency, behavioral problems, seizures, hypotonia, and intellectual developmental disability. A third of patients are amenable to treatment with high-dose oral creatine, glycine, and L-arginine supplementation. Given the limited treatment response, we initiated an open-label observational study to evaluate the effect of adjunct S-adenosyl methionine to further enhance intracerebral creatine synthesis. Significant and reproducible issues with sleep and behavior were noted in both male patients on a dose of 50/mg/kg. One of the two patients stopped S-adenosyl methionine and did not come for any follow-up. A safe and tolerable dose (17 mg/kg/day) was identified in the other patient. On magnetic resonance spectroscopy, this 8-year-old male did not show an increase in intracerebral creatine. However, significant improvement in speech/language skills, muscle mass were observed as well as in personal outcomes as defined by the family in activities related to communication and decision making. Further research is needed to assess the potential of S-adenosyl methionine as an adjunctive therapy for creatine transporter deficiency patients and to define the optimal dose. Our study also illustrates the importance of pathophysiology-based treatment, individualized outcome assessment, and patient/family participation in rare diseases research. Copyright © 2015 Elsevier Inc. All rights reserved.

Functional characterization of KanP, a methyltransferase from the kanamycin biosynthetic gene cluster of Streptomyces kanamyceticus.

Science.gov (United States)

Nepal, Keshav Kumar; Yoo, Jin Cheol; Sohng, Jae Kyung

2010-09-20

KanP, a putative methyltransferase, is located in the kanamycin biosynthetic gene cluster of Streptomyces kanamyceticus ATCC12853. Amino acid sequence analysis of KanP revealed the presence of S-adenosyl-L-methionine binding motifs, which are present in other O-methyltransferases. The kanP gene was expressed in Escherichia coli BL21 (DE3) to generate the E. coli KANP recombinant strain. The conversion of external quercetin to methylated quercetin in the culture extract of E. coli KANP proved the function of kanP as S-adenosyl-L-methionine-dependent methyltransferase. This is the first report concerning the identification of an O-methyltransferase gene from the kanamycin gene cluster. The resistant activity assay and RT-PCR analysis demonstrated the leeway for obtaining methylated kanamycin derivatives from the wild-type strain of kanamycin producer. 2009 Elsevier GmbH. All rights reserved.
A coupled photometric assay for characterization of S-adenosyl-l-homocysteine hydrolases in the physiological hydrolytic direction.

Science.gov (United States)

Kailing, Lyn L; Bertinetti, Daniela; Herberg, Friedrich W; Pavlidis, Ioannis V

2017-10-25

S-Adenosyl-l-homocysteine hydrolases (SAHases) are important metabolic enzymes and their dysregulation is associated with some severe diseases. In vivo they catalyze the hydrolysis of S-adenosyl-l-homocysteine (SAH), the by-product of methylation reactions in various organisms. SAH is a potent inhibitor of methyltransferases, thus its removal from the equilibrium is an important requirement for methylation reactions. SAH hydrolysis is also the first step in the cellular regeneration process of the methyl donor S-adenosyl-l-methionine (SAM). However, in vitro the equilibrium lies towards the synthetic direction. To enable characterization of SAHases in the physiologically relevant direction, we have developed a coupled photometric assay that shifts the equilibrium towards hydrolysis by removing the product adenosine, using a high affinity adenosine kinase (AK). This converts adenosine to AMP and thereby forms equimolar amounts of ADP, which is phosphorylated by a pyruvate kinase (PK), in turn releasing pyruvate. The readout of the assay is the consumption of NADH during the lactate dehydrogenase (LDH) catalyzed reduction of pyruvate to lactic acid. The applicability of the assay is showcased for the determination of the kinetic constants of an SAHase from Bradyrhizobium elkanii (K M,SAH 41±5μM, v max,SAH 25±1μM/min with 0.13mg/mL enzyme). This assay is a valuable tool for in vitro characterization of SAHases with biotechnological potential, and for monitoring SAHase activity in diagnostics. Copyright © 2017 Elsevier B.V. All rights reserved.
Isolation and characterization of a gene encoding a S-adenosyl-l-methionine-dependent halide/thiol methyltransferase (HTMT) from the marine diatom Phaeodactylum tricornutum: Biogenic mechanism of CH(3)I emissions in oceans.

Science.gov (United States)

Toda, Hiroshi; Itoh, Nobuya

2011-04-01

Several marine algae including diatoms exhibit S-adenosyl-l-methionine (SAM) halide/thiol methyltransferase (HTMT) activity, which is involved in the emission of methyl halides. In this study, the in vivo biogenic emission of methyl iodide from the diatom Phaeodactylum tricornutum was found to be clearly correlated with iodide concentration in the incubation media. The gene encoding HTMT (Pthtmt) was isolated from P. tricornutum CCAP 1055/1, and expressed in Escherichia coli. The molecular weight of the enzyme was 29.7kDa including a histidine tag, and the optimal pH was around pH 7.0. The kinetic properties of recombinant PtHTMT towards Cl(-), Br(-), I(-), [SH](-), [SCN](-), and SAM were 637.88mM, 72.83mM, 8.60mM, 9.92mM, 7.9mM, and 0.016mM, respectively, and were similar to those of higher-plant HTMTs, except that the activity towards thiocyanate was lower. The biogenic emission of methyl halides from the cultured cells and the enzymatic properties of HTMT suggest that the HMT/HTMT reaction is key to understanding the biogenesis of methyl halides in oceanic environments as well as terrestrial ones. Copyright © 2010 Elsevier Ltd. All rights reserved.
A Rapid and Efficient Assay for the Characterization of Substrates and Inhibitors of Nicotinamide N-Methyltransferase

NARCIS (Netherlands)

van Haren, Matthijs J; Sastre Torano, Javier; Sartini, Davide; Emanuelli, Monica; Parsons, Richard B; Martin, Nathaniel I

2016-01-01

Nicotinamide N-methyltransferase (NNMT) is one of the most abundant small molecule methyltransferases in the human body and is primarily responsible for the N-methylation of the nicotinamide (vitamin B3). Employing the cofactor S-adenosyl-l-methionine, NNMT transfers a methyl group to the pyridine
Structural Basis of Substrate Recognition in Thiopurine S-Methyltransferase

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Peng, Yi; Feng, Qiping; Wilk, Dennis; Adjei, Araba A.; Salavaggione, Oreste E.; Weinshilboum, Richard M.; Yee, Vivien C. (Case Western); (MCCM)

2008-09-23

Thiopurine S-methyltransferase (TPMT) modulates the cytotoxic effects of thiopurine prodrugs such as 6-mercaptopurine by methylating them in a reaction using S-adenosyl-l-methionine as the donor. Patients with TPMT variant allozymes exhibit diminished levels of protein and/or enzyme activity and are at risk for thiopurine drug-induced toxicity. We have determined two crystal structures of murine TPMT, as a binary complex with the product S-adenosyl-l-homocysteine and as a ternary complex with S-adenosyl-l-homocysteine and the substrate 6-mercaptopurine, to 1.8 and 2.0 {angstrom} resolution, respectively. Comparison of the structures reveals that an active site loop becomes ordered upon 6-mercaptopurine binding. The positions of the two ligands are consistent with the expected S{sub N}2 reaction mechanism. Arg147 and Arg221, the only polar amino acids near 6-mercaptopurine, are highlighted as possible participants in substrate deprotonation. To probe whether these residues are important for catalysis, point mutants were prepared in the human enzyme. Substitution of Arg152 (Arg147 in murine TPMT) with glutamic acid decreases V{sub max} and increases K{sub m} for 6-mercaptopurine but not K{sub m} for S-adenosyl-l-methionine. Substitution at this position with alanine or histidine and similar substitutions of Arg226 (Arg221 in murine TPMT) result in no effect on enzyme activity. The double mutant Arg152Ala/Arg226Ala exhibits a decreased V{sub max} and increased K{sub m} for 6-mercaptopurine. These observations suggest that either Arg152 or Arg226 may participate in some fashion in the TPMT reaction, with one residue compensating when the other is altered, and that Arg152 may interact with substrate more directly than Arg226, consistent with observations in the murine TPMT crystal structure.
Small Molecule Inhibitors That Selectively Block Dengue Virus Methyltransferase*

OpenAIRE

Lim, Siew Pheng; Sonntag, Louis Sebastian; Noble, Christian; Nilar, Shahul H.; Ng, Ru Hui; Zou, Gang; Monaghan, Paul; Chung, Ka Yan; Dong, Hongping; Liu, Boping; Bodenreider, Christophe; Lee, Gladys; Ding, Mei; Chan, Wai Ling; Wang, Gang

2010-01-01

Crystal structure analysis of Flavivirus methyltransferases uncovered a flavivirus-conserved cavity located next to the binding site for its cofactor, S-adenosyl-methionine (SAM). Chemical derivatization of S-adenosyl-homocysteine (SAH), the product inhibitor of the methylation reaction, with substituents that extend into the identified cavity, generated inhibitors that showed improved and selective activity against dengue virus methyltransferase (MTase), but not related human enzymes. Crysta...
The phenotypic and molecular assessment of the non-conserved Arabidopsis MICRORNA163/S-ADENOSYL-METHYLTRANSFERASE regulatory module during biotic stress.

Science.gov (United States)

Litholdo, Celso Gaspar; Eamens, Andrew Leigh; Waterhouse, Peter Michael

2018-04-01

In plants, microRNAs (miRNAs) have evolved in parallel to the protein-coding genes that they target for expression regulation, and miRNA-directed gene expression regulation is central to almost every cellular process. MicroRNA, miR163, is unique to the Arabidopsis genus and is processed into a 24-nucleotide (nt) mature small regulatory RNA (sRNA) from a single precursor transcript transcribed from a single locus, the MIR163 gene. The MIR163 locus is a result of a recent inverted duplication event of one of the five closely related S-ADENOSYL-METHYLTRANSFERASE genes that the mature miR163 sRNA targets for expression regulation. Currently, however, little is known about the role of the miR163/S-ADENOSYL-METHYLTRANSFERASE regulatory module in response to biotic stress. Here, we document the expression domains of MIR163 and the S-ADENOSYL-METHYLTRANSFERASE target genes following fusion of their putative promoter sequences to the β-glucuronidase (GUS) reporter gene and subsequent in planta expression. Further, we report on our phenotypic and molecular assessment of Arabidopsis thaliana plants with altered miR163 accumulation, namely the mir163-1 and mir163-2 insertion knockout mutants and the miR163 overexpression line, the MIR163-OE plant. Finally, we reveal miR163 accumulation and S-ADENOSYL-METHYLTRANSFERASE target gene expression post treatment with the defence elicitors, salicylic acid and jasmonic acid, and following Fusarium oxysporum infection, wounding, and herbivory attack. Together, the work presented here provides a comprehensive new biological insight into the role played by the Arabidopsis genus-specific miR163/S-ADENOSYL-METHYLTRANSFERASE regulatory module in normal A. thaliana development and during the exposure of A. thaliana plants to biotic stress.
(13)C-metabolic flux analysis in S-adenosyl-L-methionine production by Saccharomyces cerevisiae.

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Hayakawa, Kenshi; Kajihata, Shuichi; Matsuda, Fumio; Shimizu, Hiroshi

2015-11-01

S-Adenosyl-L-methionine (SAM) is a major biological methyl group donor, and is used as a nutritional supplement and prescription drug. Yeast is used for the industrial production of SAM owing to its high intracellular SAM concentrations. To determine the regulation mechanisms responsible for such high SAM production, (13)C-metabolic flux analysis ((13)C-MFA) was conducted to compare the flux distributions in the central metabolism between Kyokai no. 6 (high SAM-producing) and S288C (control) strains. (13)C-MFA showed that the levels of tricarboxylic acid (TCA) cycle flux in SAM-overproducing strain were considerably increased compared to those in the S228C strain. Analysis of ATP balance also showed that a larger amount of excess ATP was produced in the Kyokai 6 strain because of increased oxidative phosphorylation. These results suggest that high SAM production in Kyokai 6 strains could be attributed to enhanced ATP regeneration with high TCA cycle fluxes and respiration activity. Thus, maintaining high respiration efficiency during cultivation is important for improving SAM production. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
Crystallization and preliminary X-ray crystallographic analysis of the ArsM arsenic(III) S-adenosylmethionine methyltransferase

International Nuclear Information System (INIS)

Marapakala, Kavitha; Ajees, A. Abdul; Qin, Jie; Sankaran, Banumathi; Rosen, Barry P.

2010-01-01

A common biotransformation of arsenic is methylation to monomethylated, dimethylated and trimethylated species, which is catalyzed by the ArsM (or AS3MT) arsenic(III) S-adenosylmethionine methyltransferase. ArsM from the acidothermophilic alga Cyanidioschyzon sp. 5508 was expressed, purified and crystallized by the hanging-drop vapor-diffusion method and diffraction data were collected to 1.76 Å resolution. Arsenic is the most ubiquitous environmental toxin and carcinogen and consequently ranks first on the Environmental Protection Agency’s Superfund Priority List of Hazardous Substances. It is introduced primarily from geochemical sources and is acted on biologically, creating an arsenic biogeocycle. A common biotransformation is methylation to monomethylated, dimethylated and trimethylated species. Methylation is catalyzed by the ArsM (or AS3MT) arsenic(III) S-adenosylmethionine methyltransferase, an enzyme (EC 2.1.1.137) that is found in members of every kingdom from bacteria to humans. ArsM from the thermophilic alga Cyanidioschyzon sp. 5508 was expressed, purified and crystallized. Crystals were obtained by the hanging-drop vapor-diffusion method. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 84.85, b = 46.89, c = 100.35 Å, β = 114.25° and one molecule in the asymmetric unit. Diffraction data were collected at the Advanced Light Source and were processed to a resolution of 1.76 Å
Purification, crystallization and preliminary crystallographic studies of plant S-adenosyl-l-homocysteine hydrolase (Lupinus luteus)

Energy Technology Data Exchange (ETDEWEB)

Brzezinski, Krzysztof [Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan (Poland); Department of Crystallography, Faculty of Chemistry, A. Mickiewicz University, Poznan (Poland); Bujacz, Grzegorz [Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan (Poland); Faculty of Food Chemistry and Biotechnology, Technical University of Lodz (Poland); Jaskolski, Mariusz, E-mail: mariuszj@amu.edu.pl [Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan (Poland); Department of Crystallography, Faculty of Chemistry, A. Mickiewicz University, Poznan (Poland)

2008-07-01

Single crystals of recombinant S-adenosyl-l-homocysteine hydrolase from L. luteus in complex with adenosine diffract X-rays to 1.17 Å resolution at 100 K. The crystals are tetragonal, space group P4{sub 3}2{sub 1}2, and contain one copy of the dimeric enzyme in the asymmetric unit. By degrading S-adenosyl-l-homocysteine, which is a byproduct of S-adenosyl-l-methionine-dependent methylation reactions, S-adenosyl-l-homocysteine hydrolase (SAHase) acts as a regulator of cellular methylation processes. S-Adenosyl-l-homocysteine hydrolase from the leguminose plant yellow lupin (Lupinus luteus), LlSAHase, which is composed of 485 amino acids and has a molecular weight of 55 kDa, has been cloned, expressed in Escherichia coli and purified. Crystals of LlSAHase in complex with adenosine were obtained by the hanging-drop vapour-diffusion method using 20%(w/v) PEG 4000 and 10%(v/v) 2-propanol as precipitants in 0.1 M Tris–HCl buffer pH 8.0. The crystals were tetragonal, space group P4{sub 3}2{sub 1}2, with unit-cell parameters a = 122.4, c = 126.5 Å and contained two protein molecules in the asymmetric unit, corresponding to the functional dimeric form of the enzyme. Atomic resolution (1.17 Å) X-ray diffraction data have been collected using synchrotron radiation.
Purification, crystallization and preliminary crystallographic studies of plant S-adenosyl-l-homocysteine hydrolase (Lupinus luteus)

International Nuclear Information System (INIS)

Brzezinski, Krzysztof; Bujacz, Grzegorz; Jaskolski, Mariusz

2008-01-01

Single crystals of recombinant S-adenosyl-l-homocysteine hydrolase from L. luteus in complex with adenosine diffract X-rays to 1.17 Å resolution at 100 K. The crystals are tetragonal, space group P4 3 2 1 2, and contain one copy of the dimeric enzyme in the asymmetric unit. By degrading S-adenosyl-l-homocysteine, which is a byproduct of S-adenosyl-l-methionine-dependent methylation reactions, S-adenosyl-l-homocysteine hydrolase (SAHase) acts as a regulator of cellular methylation processes. S-Adenosyl-l-homocysteine hydrolase from the leguminose plant yellow lupin (Lupinus luteus), LlSAHase, which is composed of 485 amino acids and has a molecular weight of 55 kDa, has been cloned, expressed in Escherichia coli and purified. Crystals of LlSAHase in complex with adenosine were obtained by the hanging-drop vapour-diffusion method using 20%(w/v) PEG 4000 and 10%(v/v) 2-propanol as precipitants in 0.1 M Tris–HCl buffer pH 8.0. The crystals were tetragonal, space group P4 3 2 1 2, with unit-cell parameters a = 122.4, c = 126.5 Å and contained two protein molecules in the asymmetric unit, corresponding to the functional dimeric form of the enzyme. Atomic resolution (1.17 Å) X-ray diffraction data have been collected using synchrotron radiation
A comprehensive review on the efficacy of S-Adenosyl-L-methionine in Major Depressive Disorder.

Science.gov (United States)

De Berardis, Domenico; Orsolini, Laura; Serroni, Nicola; Girinelli, Gabriella; Iasevoli, Felice; Tomasetti, Carmine; de Bartolomeis, Andrea; Mazza, Monica; Valchera, Alessandro; Fornaro, Michele; Perna, Giampaolo; Piersanti, Monica; Di Nicola, Marco; Cavuto, Marilde; Martinotti, Giovanni; Di Giannantonio, Massimo

2016-01-01

To review the antidepressant efficacy of S-Adenosyl-L-Methionine (SAMe) both in monotherapy and/or in augmentation with antidepressants to better understand its potential role in the treatment of patients with Major Depressive Disorder (MDD) and Treatment-Resistant Depression (TRD). A MEDLINE/PubMed search was carried out by using the following set of keywords: ((SAMe OR SAdenosyl- L-Methionine) AND (major depressive disorder OR depression)). Data Selection and Data Extraction: No language or time restrictions were placed on the electronic searches. Randomized controlled trials and open trials involving humans were here included and analyzed. The references of published articles identified in the initial search process were also examined for any additional studies appropriate for the review. SAMe is an important physiologic compound, playing a central role as precursor molecule in several biochemical reactions. Numerous studies have shown that SAMe may affect the regulation of various critical components of monoaminergic neurotransmission involved in the pathophysiology of MDD. Some findings have suggested its antidepressant efficacy in treating MDD. Several randomized controlled trials have supported that the antidepressant efficacy of SAMe in monotherapy is superior to placebo and tricyclic antidepressants. Recent findings have also demonstrated its efficacy in patients nonresponsive to selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors. Overall, SAMe is a well-tolerated medication, which may offer considerable advantages as an alternative to antidepressant drugs or as an add-on therapy in the treatment of MDD and TRD. More large-scale controlled trials are needed to gain a better understanding of the relative efficacy of this drug.
Modification of -Adenosyl--Homocysteine as Inhibitor of Nonstructural Protein 5 Methyltransferase Dengue Virus Through Molecular Docking and Molecular Dynamics Simulation

Directory of Open Access Journals (Sweden)

Usman Sumo Friend Tambunan

2017-04-01

Full Text Available Dengue fever is still a major threat worldwide, approximately threatening two-fifths of the world’s population in tropical and subtropical countries. Nonstructural protein 5 (NS5 methyltransferase enzyme plays a vital role in the process of messenger RNA capping of dengue by transferring methyl groups from S -adenosyl- l -methionine to N7 atom of the guanine bases of RNA and the RNA ribose group of 2′OH, resulting in S -adenosyl- l -homocysteine (SAH. The modification of SAH compound was screened using molecular docking and molecular dynamics simulation, along with computational ADME-Tox (absorption, distribution, metabolism, excretion, and toxicity test. The 2 simulations were performed using Molecular Operating Environment (MOE 2008.10 software, whereas the ADME-Tox test was performed using various software. The modification of SAH compound was done using several functional groups that possess different polarities and properties, resulting in 3460 ligands to be docked. After conducting docking simulation, we earned 3 best ligands (SAH-M331, SAH-M2696, and SAH-M1356 based on ΔG binding and molecular interactions, which show better results than the standard ligands. Moreover, the results of molecular dynamics simulation show that the best ligands are still able to maintain the active site residue interaction with the binding site until the end of the simulation. After a series of molecular docking and molecular dynamics simulation were performed, we concluded that SAH-M1356 ligand is the most potential SAH-based compound to inhibit NS5 methyltransferase enzyme for treating dengue fever.
S-Adenosyl-L-methionine protects the probiotic yeast, Saccharomyces boulardii, from acid-induced cell death.

Science.gov (United States)

Cascio, Vincent; Gittings, Daniel; Merloni, Kristen; Hurton, Matthew; Laprade, David; Austriaco, Nicanor

2013-02-13

Saccharomyces boulardii is a probiotic yeast routinely used to prevent and to treat gastrointestinal disorders, including the antibiotic-associated diarrhea caused by Clostridium difficile infections. However, only 1-3% of the yeast administered orally is recovered alive in the feces suggesting that this yeast is unable to survive the acidic environment of the gastrointestinal tract. We provide evidence that suggests that S. boulardii undergoes programmed cell death (PCD) in acidic environments, which is accompanied by the generation of reactive oxygen species and the appearance of caspase-like activity. To better understand the mechanism of cell death at the molecular level, we generated microarray gene expression profiles of S. boulardii cells cultured in an acidic environment. Significantly, functional annotation revealed that the up-regulated genes were significantly over-represented in cell death pathways Finally, we show that S-adenosyl-L-methionine (AdoMet), a commercially available, FDA-approved dietary supplement, enhances the viability of S. boulardii in acidic environments, most likely by preventing programmed cell death. In toto, given the observation that many of the proven health benefits of S. boulardii are dependent on cell viability, our data suggests that taking S. boulardii and AdoMet together may be a more effective treatment for gastrointestinal disorders than taking the probiotic yeast alone.
Rapid and Quantitative Determination of S-Adenosyl-L-Methionine in the Fermentation Process by Surface-Enhanced Raman Scattering

Directory of Open Access Journals (Sweden)

Hairui Ren

2016-01-01

Full Text Available Concentrations of S-Adenosyl-L-Methionine (SAM in aqueous solution and fermentation liquids were quantitatively determined by surface-enhanced Raman scattering (SERS and verified by high-pressure liquid chromatography (HPLC. The Ag nanoparticle/silicon nanowire array substrate was fabricated and employed as an active SERS substrate to indirectly measure the SAM concentration. The linear relationship between the integrated intensity of peak centered at ~2920 cm−1 in SERS spectra and the SAM concentration was established, and the limit of detections of SAM concentrations was analyzed to be ~0.1 g/L. The concentration of SAM in real solution could be predicted by the linear relationship and verified by the HPLC detection method. The relative deviations (δ of the predicted SAM concentration are less than 13% and the correlation coefficient is 0.9998. Rolling-Circle Filter was utilized to subtract fluorescence background and the optimal results were obtained when the radius of the analyzing circle is 650 cm−1.
Small Molecule Inhibitors That Selectively Block Dengue Virus Methyltransferase*

Science.gov (United States)

Lim, Siew Pheng; Sonntag, Louis Sebastian; Noble, Christian; Nilar, Shahul H.; Ng, Ru Hui; Zou, Gang; Monaghan, Paul; Chung, Ka Yan; Dong, Hongping; Liu, Boping; Bodenreider, Christophe; Lee, Gladys; Ding, Mei; Chan, Wai Ling; Wang, Gang; Jian, Yap Li; Chao, Alexander Theodore; Lescar, Julien; Yin, Zheng; Vedananda, T. R.; Keller, Thomas H.; Shi, Pei-Yong

2011-01-01

Crystal structure analysis of Flavivirus methyltransferases uncovered a flavivirus-conserved cavity located next to the binding site for its cofactor, S-adenosyl-methionine (SAM). Chemical derivatization of S-adenosyl-homocysteine (SAH), the product inhibitor of the methylation reaction, with substituents that extend into the identified cavity, generated inhibitors that showed improved and selective activity against dengue virus methyltransferase (MTase), but not related human enzymes. Crystal structure of dengue virus MTase with a bound SAH derivative revealed that its N6-substituent bound in this cavity and induced conformation changes in residues lining the pocket. These findings demonstrate that one of the major hurdles for the development of methyltransferase-based therapeutics, namely selectivity for disease-related methyltransferases, can be overcome. PMID:21147775
Crystallization of mouse S-adenosyl-l-homocysteine hydrolase

International Nuclear Information System (INIS)

Ishihara, Masaaki; Kusakabe, Yoshio; Ohsumichi, Tsuyoshi; Tanaka, Nobutada; Nakanishi, Masayuki; Kitade, Yukio; Nakamura, Kazuo T.

2010-01-01

Mouse S-adenosyl-l-homocysteine hydrolase has been crystallized in the presence of the reaction product adenosine. Diffraction data to 1.55 Å resolution were collected using synchrotron radiation. S-Adenosyl-l-homocysteine hydrolase (SAHH; EC 3.3.1.1) catalyzes the reversible hydrolysis of S-adenosyl-l-homocysteine to adenosine and l-homocysteine. For crystallographic investigations, mouse SAHH (MmSAHH) was overexpressed in bacterial cells and crystallized using the hanging-drop vapour-diffusion method in the presence of the reaction product adenosine. X-ray diffraction data to 1.55 Å resolution were collected from an orthorhombic crystal form belonging to space group I222 with unit-cell parameters a = 100.64, b = 104.44, c = 177.31 Å. Structural analysis by molecular replacement is in progress
Crystal structure of MboIIA methyltransferase

OpenAIRE

Osipiuk, Jerzy; Walsh, Martin A.; Joachimiak, Andrzej

2003-01-01

DNA methyltransferases (MTases) are sequence-specific enzymes which transfer a methyl group from S-adenosyl-l-methionine (AdoMet) to the amino group of either cytosine or adenine within a recognized DNA sequence. Methylation of a base in a specific DNA sequence protects DNA from nucleolytic cleavage by restriction enzymes recognizing the same DNA sequence. We have determined at 1.74 Å resolution the crystal structure of a β-class DNA MTase MboIIA (M·MboIIA) from the bacterium Moraxella bovis,...
Overexpression of S-adenosyl-L-methionine synthetase increased tomato tolerance to alkali stress through polyamine metabolism.

Science.gov (United States)

Gong, Biao; Li, Xiu; VandenLangenberg, Kyle M; Wen, Dan; Sun, Shasha; Wei, Min; Li, Yan; Yang, Fengjuan; Shi, Qinghua; Wang, Xiufeng

2014-08-01

S-adenosyl-L-methionine (SAM) synthetase is the key enzyme involved in the biosynthesis of SAM, which serves as a common precursor for polyamines (PAs) and ethylene. A SAM synthetase cDNA (SlSAMS1) was introduced into the tomato genome using the Agrobacterium tumefaciens transformation method. Transgenic plants overexpressing SlSAMS1 exhibited a significant increase in tolerance to alkali stress and maintained nutrient balance, higher photosynthetic capacity and lower oxidative stress compared with WT lines. Both in vivo and in vitro experiments indicated that the function of SlSAMS1 mainly depended on the accumulation of Spd and Spm in the transgenic lines. A grafting experiment showed that rootstocks from SlSAMS1-overexpressing plants provided a stronger root system, increased PAs accumulation, essential elements absorption, and decreased Na(+) absorption in the scions under alkali stress. As a result, fruit set and yield were significantly enhanced. To our knowledge, this is the first report to provide evidence that SlSAMS1 positively regulates tomato tolerance to alkali stress and plays a major role in modulating polyamine metabolism, resulting in maintainability of nutrient and ROS balance. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.
Structural insight into maintenance methylation by mouse DNA methyltransferase 1 (Dnmt1)

Science.gov (United States)

Takeshita, Kohei; Suetake, Isao; Yamashita, Eiki; Suga, Michihiro; Narita, Hirotaka; Nakagawa, Atsushi; Tajima, Shoji

2011-01-01

Methylation of cytosine in DNA plays a crucial role in development through inheritable gene silencing. The DNA methyltransferase Dnmt1 is responsible for the propagation of methylation patterns to the next generation via its preferential methylation of hemimethylated CpG sites in the genome; however, how Dnmt1 maintains methylation patterns is not fully understood. Here we report the crystal structure of the large fragment (291–1620) of mouse Dnmt1 and its complexes with cofactor S-adenosyl-L-methionine and its product S-adenosyl-L-homocystein. Notably, in the absence of DNA, the N-terminal domain responsible for targeting Dnmt1 to replication foci is inserted into the DNA-binding pocket, indicating that this domain must be removed for methylation to occur. Upon binding of S-adenosyl-L-methionine, the catalytic cysteine residue undergoes a conformation transition to a catalytically competent position. For the recognition of hemimethylated DNA, Dnmt1 is expected to utilize a target recognition domain that overhangs the putative DNA-binding pocket. Taking into considerations the recent report of a shorter fragment structure of Dnmt1 that the CXXC motif positions itself in the catalytic pocket and prevents aberrant de novo methylation, we propose that maintenance methylation is a multistep process accompanied by structural changes. PMID:21518897

Insulin stimulation of phospholipid methylation in isolated rat adipocyte plasma membranes.

OpenAIRE

Kelly, K L; Kiechle, F L; Jarett, L

1984-01-01

Partially purified plasma membranes prepared from rat adipocytes contain N-methyltransferase(s) that utilize(s) S-adenosyl-L-methionine to synthesize phosphatidylcholine from phosphatidylethanolamine. The incorporation of [3H]methyl from S-adenosyl-L-[methyl-3H]methionine into plasma membrane phospholipids was linear with incubation time and plasma membrane protein concentration and was inhibited in a dose-dependent manner by both S-adenosyl-L-homocysteine and 3-deazadenosine. The addition of...
Characterization of Trypanosoma brucei brucei S-adenosyl-L-methionine decarboxylase and its inhibition by Berenil, pentamidine and methylglyoxal bis(guanylhydrazone).

Science.gov (United States)

Bitonti, A J; Dumont, J A; McCann, P P

1986-01-01

Trypanosoma brucei brucei S-adenosyl-L-methionine (AdoMet) decarboxylase was found to be relatively insensitive to activation by putrescine as compared with the mammalian enzyme, being stimulated by only 50% over a 10,000-fold range of putrescine concentrations. The enzyme was not stimulated by up to 10 mM-Mg2+. The Km for AdoMet was 30 microM, similar to that of other eukaryotic AdoMet decarboxylases. T.b. brucei AdoMet decarboxylase activity was apparently irreversibly inhibited in vitro by Berenil and reversibly by pentamidine and methylglyoxal bis(guanylhydrazone). Berenil also inhibited trypanosomal AdoMet decarboxylase by 70% within 4 h after administration to infected rats and markedly increased the concentration of putrescine in trypanosomes that were exposed to the drug in vivo. Spermidine and spermine blocked the curative effect of Berenil on model mouse T.b. brucei infections. This effect of the polyamines was probably not due to reversal of Berenil's inhibitory effects on the AdoMet decarboxylase. PMID:3800910
Improving the productivity of S-adenosyl-l-methionine by metabolic engineering in an industrial Saccharomyces cerevisiae strain.

Science.gov (United States)

Zhao, Weijun; Hang, Baojian; Zhu, Xiangcheng; Wang, Ri; Shen, Minjie; Huang, Lei; Xu, Zhinan

2016-10-20

S-Adenosyl-l-methionine (SAM) is an important metabolite having prominent roles in treating various diseases. In order to improve the production of SAM, the regulation of three metabolic pathways involved in SAM biosynthesis were investigated in an industrial yeast strain ZJU001. GLC3 encoded glycogen-branching enzyme (GBE), SPE2 encoded SAM decarboxylase, as well as ERG4 and ERG6 encoded key enzymes in ergosterol biosynthesis, were knocked out in ZJU001 accordingly. The results indicated that blocking of either glycogen pathway or SAM decarboxylation pathway could improve the SAM accumulation significantly in ZJU001, while single disruption of either ERG4 or ERG6 gene had no obvious effect on SAM production. Moreover, the double mutant ZJU001-GS with deletion of both GLC3 and SPE2 genes was also constructed, which showed further improvement of SAM accumulation. Finally, SAM2 was overexpressed in ZJU001-GS to give the best SAM-producing recombinant strain ZJU001-GS-SAM2, in which 12.47g/L SAM was produced by following our developed pseudo-exponential fed-batch cultivation strategy, about 81.0% increase comparing to its parent strain ZJU001. The present work laid a solid base for large-scale SAM production with the industrial Saccharomyces cerevisiae strain. Copyright © 2016 Elsevier B.V. All rights reserved.
Palliative treatment for advanced biliary adenocarcinomas with combination dimethyl sulfoxide-sodium bicarbonate infusion and S-adenosyl-L-methionine.

Science.gov (United States)

Hoang, Ba X; Tran, Hung Q; Vu, Ut V; Pham, Quynh T; Shaw, D Graeme

2014-09-01

Adenocarcinoma of the gallbladder and cholangiocarcinoma account for 4% and 3%, respectively, of all gastrointestinal cancers. Advanced biliary tract carcinoma has a very poor prognosis with all current available modalities of treatment. In this pilot open-label study, the authors investigated the efficacy and safety of a combination of dimethyl sulfoxide-sodium bicarbonate (DMSO-SB) infusion and S-adenosyl-L-methionine (ademetionine) oral supplementation as palliative pharmacotherapy in nine patients with advanced nonresectable biliary tract carcinomas (ABTCs). Patients with evidence of biliary obstruction with a total serum bilirubin ≤300 μmol/L were allowed to join the study. The results of this 6-month study and follow-up of all nine patients with ABTC indicated that the investigated combination treatment improved pain control, blood biochemical parameters, and quality of life for the patients. Moreover, this method of treatment has led to a 6-month progression-free survival for all investigated patients. The treatment was well tolerated for all patients without major adverse reactions. Given that ABTC is a highly fatal malignancy with poor response to chemotherapy and targeted drugs, the authors consider that the combination of DMSO-SB and ademetionine deserves further research and application as a palliative care and survival-enhancing treatment for this group of patients.
A novel multifunctional O-methyltransferase implicated in a dual methylation pathway associated with lignin biosynthesis in loblolly pine

OpenAIRE

Li, Laigeng; Popko, Jacqueline L.; Zhang, Xing-Hai; Osakabe, Keishi; Tsai, Chung-Jui; Joshi, Chandrashekhar P.; Chiang, Vincent L.

1997-01-01

S-adenosyl-l-methionine (SAM)-dependent O-methyltransferases (OMTs) catalyze the methylation of hydroxycinnamic acid derivatives for the synthesis of methylated plant polyphenolics, including lignin. The distinction in the extent of methylation of lignins in angiosperms and gymnosperms, mediated by substrate-specific OMTs, represents one of the fundamental differences in lignin biosynthesis between these two classes of plants. In angiosperms, two types of structurally and functionally distinc...
Mutations in the histamine N-methyltransferase gene, HNMT, are associated with nonsyndromic autosomal recessive intellectual disability

OpenAIRE

Heidari, Abolfazl; Tongsook, Chanakan; Najafipour, Reza; Musante, Luciana; Vasli, Nasim; Garshasbi, Masoud; Hu, Hao; Mittal, Kirti; McNaughton, Amy J. M.; Sritharan, Kumudesh; Hudson, Melissa; Stehr, Henning; Talebi, Saeid; Moradi, Mohammad; Darvish, Hossein

2015-01-01

Histamine (HA) acts as a neurotransmitter in the brain, which participates in the regulation of many biological processes including inflammation, gastric acid secretion and neuromodulation. The enzyme histamine N-methyltransferase (HNMT) inactivates HA by transferring a methyl group from S-adenosyl-l-methionine to HA, and is the only well-known pathway for termination of neurotransmission actions of HA in mammalian central nervous system. We performed autozygosity mapping followed by targeted...
Influence of Threonine Metabolism on S-adenosyl-methionine and Histone Methylation

Science.gov (United States)

Shyh-Chang, Ng; Locasale, Jason W.; Lyssiotis, Costas A.; Zheng, Yuxiang; Teo, Ren Yi; Ratanasirintrawoot, Sutheera; Zhang, Jin; Onder, Tamer; Unternaehrer, Juli J.; Zhu, Hao; Asara, John M.; Daley, George Q.; Cantley, Lewis C.

2013-01-01

Threonine is the only amino acid critically required for the pluripotency of mouse embryonic stem cells (mESCs) but the detailed mechanism remains unclear. We found that threonine (Thr) and S-adenosyl-methionine (SAM) metabolism are coupled in pluripotent stem cells, resulting in regulation of histone methylation. Isotope labeling of mESCs revealed that Thr provides a substantial fraction of both the cellular glycine (Gly) and the acetyl-coenzyme A (CoA) needed for SAM synthesis. Depletion of Thr from the culture medium or threonine dehydrogenase (Tdh) from mESCs decreased accumulation of SAM and decreased tri-methylation of histone H3 lysine-4 (H3K4me3), leading to slowed growth, and increased differentiation. Thus abundance of SAM appears to influence H3K4me3, providing a possible mechanism by which modulation of a metabolic pathway might influence stem cell fate. PMID:23118012
Crystal structures of the methyltransferase and helicase from the ZIKA 1947 MR766 Uganda strain

Energy Technology Data Exchange (ETDEWEB)

Bukrejewska, Malgorzata; Derewenda, Urszula; Radwanska, Malwina; Engel, Daniel A.; Derewenda, Zygmunt S.

2017-08-15

Two nonstructural proteins encoded byZika virusstrain MR766 RNA, a methyltransferase and a helicase, were crystallized and their structures were solved and refined at 2.10 and 2.01 Å resolution, respectively. The NS5 methyltransferase contains a boundS-adenosyl-L-methionine (SAM) co-substrate. The NS3 helicase is in the apo form. Comparison with published crystal structures of the helicase in the apo, nucleotide-bound and single-stranded RNA (ssRNA)-bound states suggests that binding of ssRNA to the helicase may occur through conformational selection rather than induced fit.
A simple radioactivity assay for measurement of methionine adenosyltransferase activity by aqueous chromatography

International Nuclear Information System (INIS)

Oeztuerk, M.; Lemonnier, F.; Cresteil, D.; Lemonnier, A.

1983-01-01

Methionine adenosyltransferase (ATP:L-methionine S-adenosyltransferase, EC 2.5.1.6) catalyzes the formation of S-adenosyl-L-methionine from ATP and L-methionine. Methionine metabolism is very important in human pathology. Methionine adenosyltransferase deficiency has recently been shown to be a specific enzymatic defect, whereas certain other diseases have only been associated with non-specific deficiencies of methionine adenosyltransferase. These different reasons explain the existence of numerous reports concerning the determination of hepatic methionine adenosyltransferase and of its isozymic forms, found in different tissues in man and rat. On the basis of the work of Chou and Lombardini, the authors report a rapid, sensitive technique using aqueous chromatography with phosphocellulose ion exchange paper to separate the S-adenosyl L-[methyl- 14 C]methionine from L-[methyl- 14 C]methionine. (Auth.)
Structural characterization of the mitomycin 7-O-methyltransferase

Energy Technology Data Exchange (ETDEWEB)

Singh, Shanteri; Chang, Aram; Goff, Randal D.; Bingman, Craig A.; Grüschow, Sabine; Sherman, David H.; Phillips, Jr., George N.; Thorson, Jon S. (Michigan); (UW)

2014-10-02

Mitomycins are quinone-containing antibiotics, widely used as antitumor drugs in chemotherapy. Mitomycin-7-O-methyltransferase (MmcR), a key tailoring enzyme involved in the biosynthesis of mitomycin in Streptomyces lavendulae, catalyzes the 7-O-methylation of both C9{beta}- and C9{alpha}-configured 7-hydroxymitomycins. We have determined the crystal structures of the MmcR-S-adenosylhomocysteine (SAH) binary complex and MmcR-SAH-mitomycin A (MMA) ternary complex at resolutions of 1.9 and 2.3 {angstrom}, respectively. The study revealed MmcR to adopt a common S-adenosyl-L-methionine-dependent O-methyltransferase fold and the presence of a structurally conserved active site general acid-base pair is consistent with a proton-assisted methyltransfer common to most methyltransferases. Given the importance of C7 alkylation to modulate mitomycin redox potential, this study may also present a template toward the future engineering of catalysts to generate uniquely bioactive mitomycins.
Structural insights into mechanisms of the small RNA methyltransferase HEN1

Energy Technology Data Exchange (ETDEWEB)

Huang, Ying; Ji, Lijuan; Huang, Qichen; Vassylyev, Dmitry G.; Chen, Xuemei; Ma, Jin-Biao; (UAB); (UCR)

2010-02-22

RNA silencing is a conserved regulatory mechanism in fungi, plants and animals that regulates gene expression and defence against viruses and transgenes. Small silencing RNAs of {approx}20-30 nucleotides and their associated effector proteins, the Argonaute family proteins, are the central components in RNA silencing. A subset of small RNAs, such as microRNAs and small interfering RNAs (siRNAs) in plants, Piwi-interacting RNAs in animals and siRNAs in Drosophila, requires an additional crucial step for their maturation; that is, 2'-O-methylation on the 3' terminal nucleotide. A conserved S-adenosyl-L-methionine-dependent RNA methyltransferase, HUA ENHANCER 1 (HEN1), and its homologues are responsible for this specific modification. Here we report the 3.1 {angstrom} crystal structure of full-length HEN1 from Arabidopsis in complex with a 22-nucleotide small RNA duplex and cofactor product S-adenosyl-L-homocysteine. Highly cooperative recognition of the small RNA substrate by multiple RNA binding domains and the methyltransferase domain in HEN1 measures the length of the RNA duplex and determines the substrate specificity. Metal ion coordination by both 2' and 3' hydroxyls on the 3'-terminal nucleotide and four invariant residues in the active site of the methyltransferase domain suggests a novel Mg{sup 2+}-dependent 2'-O-methylation mechanism.
Terpenoid Metabolism in Plastids 1

Science.gov (United States)

Camara, Bilal; Bardat, Françoise; Seye, Ababacar; D'Harlingue, Alain; Monéger, René

1982-01-01

The synthesis of α-tocopherol from 2,3-dimethylphytylquinol and S-adenosyl-l-methionine was achieved using Capsicum annuum fruit chromoplasts. The enzymes involved in the cyclization (2,3-dimethyl-phytylquinol cyclase) and methylation (S-adenosyl methionine:γ-tocopherol methyl-transferase) are both localized in the chromoplast membrane fraction (envelopes and/or a-chlorophyll lamellae), in contrast to the stroma fraction. PMID:16662717
Temporal study of acetaminophen (APAP) and S-adenosyl-L-methionine (SAMe) effects on subcellular hepatic SAMe levels and methionine adenosyltransferase (MAT) expression and activity

International Nuclear Information System (INIS)

Brown, J. Michael; Ball, John G.; Hogsett, Amy; Williams, Tierra; Valentovic, Monica

2010-01-01

Acetaminophen (APAP) is the leading cause of drug induced liver failure in the United States. Previous studies in our laboratory have shown that S-adenosyl methionine (SAMe) is protective for APAP hepatic toxicity. SAMe is critical for glutathione synthesis and transmethylation of nucleic acids, proteins and phospholipids which would facilitate recovery from APAP toxicity. SAMe is synthesized in cells through the action of methionine adenosyltransferase (MAT). This study tested the hypothesis that total hepatic and subcellular SAMe levels are decreased by APAP toxicity. Studies further examined MAT expression and activity in response to APAP toxicity. Male C57BL/6 mice (16-22 g) were treated with vehicle (Veh; water 15 ml/kg ip injections), 250 mg/kg APAP (15 ml/kg, ip), SAMe (1.25 mmol/kg) or SAMe administered 1 h after APAP injection (SAMe and SAMe + APAP). Hepatic tissue was collected 2, 4, and 6 h after APAP administration. Levels of SAMe and its metabolite S-adenosylhomocysteine (SAH) were determined by HPLC analysis. MAT expression was examined by Western blot. MAT activity was determined by fluorescence assay. Total liver SAMe levels were depressed at 4 h by APAP overdose, but not at 2 or 6 h. APAP depressed mitochondrial SAMe levels at 4 and 6 h relative to the Veh group. In the nucleus, levels of SAMe were depressed below detectable limits 4 h following APAP administration. SAMe administration following APAP (SAMe + APAP) prevented APAP associated decline in mitochondrial and nuclear SAMe levels. In conclusion, the maintenance of SAMe may provide benefit in preventing damage associated with APAP toxicity.
S-Adenosylmethionine and S-adenosylhomocystein metabolism in isolated rat liver. Effects of L-methionine, L-homocystein, and adenosine.

Science.gov (United States)

Hoffman, D R; Marion, D W; Cornatzer, W E; Duerre, J A

1980-11-25

The effects of varying concentrations of L-methionine, L-homocysteine, and adenosine on the tissue levels of S-adenosylmethionine (AdoMet) and S-adenosyl-homocystein (AdoHcy) were investigated in perfused liver. In the normal liver, the intracellular concentration of AdoMet was dependent upon the availability of methionine. In the presence of high concentrations of methionine the maximum level of AdoMet attainable was 300 nmol/g of liver. The exogenous concentration of methionine did not alter the hepatic concentration of AdoHcy (8 to 20 nmol/g) while adenosine or homocysteine blocked hydrolysis of AdoHcy resulting in elevated levels of AdoHcy (400 to 600 nmol/g) and AdoMet (300 to 600 nmol/g). The addition of both adenosine (4mM) and homocysteine (3.4 mM) to the perfusate further increased the levels of AdoHcy (4 mumol/g) and AdoMet (1.2 mumol/g). As the concentration of AdoHcy increased, significant amounts of this compound were released into the perfusate, while AdoMet was not detected. Under all conditions where AdoHcy accumulated in the cell, a concomitant increase in the AdoMet level occurred. Apparently AdoHcy acts as a positive effector of the S-adenosylmethionine synthase. The hepatocytes did not take up significant amounts of [methyl-14C]AdoMet from the perfusate nor were any [14C]methyl groups from this compound incorporated into histones, DNA, or phospholipids. In contrast, [14C]methyl groups were readily incorporated into these macromolecules from exogenous [methyl-14C]methionine. The addition of adenosine (4 mM) and homocystein (3.4 mM) shifted the AdoMet:AdoHcy ratio from 8.2 to 0.3. Under these conditions, transmethylation was inhibited markedly.
Distinction between the Cfr Methyltransferase Conferring Antibiotic Resistance and the Housekeeping RlmN Methyltransferase

DEFF Research Database (Denmark)

Atkinson, Gemma C; Hansen, Lykke H; Tenson, Tanel

2013-01-01

The cfr gene encodes the Cfr methyltransferase that primarily methylates C-8 in A2503 of 23S rRNA in the peptidyl transferase region of bacterial ribosomes. The methylation provides resistance to six classes of antibiotics of clinical and veterinary importance. The rlmN gene encodes the Rlm......N methyltransferase that methylates C-2 in A2503 in 23S rRNA and A37 in tRNA, but RlmN does not significantly influence antibiotic resistance. The enzymes are homologous and use the same mechanism involving radical S-adenosyl methionine to methylate RNA via an intermediate involving a methylated cysteine....... The differentiation between the two classes is supported by previous and new experimental evidence from antibiotic resistance, primer extensions, and mass spectrometry. Finally, evolutionary aspects of the distribution of Cfr- and RlmN-like enzymes are discussed....
Biosynthesis of estragole and methyl-eugenol in sweet basil (Ocimum basilicum L). Developmental and chemotypic association of allylphenol O-methyltransferase activities.

Science.gov (United States)

Lewinsohn, E; Ziv-Raz, I; Dudai, N; Tadmor, Y; Lastochkin, E; Larkov, O; Chaimovitsh, D; Ravid, U; Putievsky, E; Pichersky, E; Shoham, Y

2000-12-07

Sweet basil (Ocimum basilicum L., Lamiaceae) is a common herb, used for culinary and medicinal purposes. The essential oils of different sweet basil chemotypes contain various proportions of the allyl phenol derivatives estragole (methyl chavicol), eugenol, and methyl eugenol, as well as the monoterpene alcohol linalool. To monitor the developmental regulation of estragole biosynthesis in sweet basil, an enzymatic assay for S-adenosyl-L-methionine (SAM):chavicol O-methyltransferase activity was developed. Young leaves display high levels of chavicol O-methyltransferase activity, but the activity was negligible in older leaves, indicating that the O-methylation of chavicol primarily occurs early during leaf development. The O-methyltransferase activities detected in different sweet basil genotypes differed in their substrate specificities towards the methyl acceptor substrate. In the high-estragole-containing chemotype R3, the O-methyltransferase activity was highly specific for chavicol, while eugenol was virtually not O-methylated. In contrast, chemotype 147/97, that contains equal levels of estragole and methyl eugenol, displayed O-methyltransferase activities that accepted both chavicol and eugenol as substrates, generating estragole and methyl eugenol, respectively. Chemotype SW that contains high levels of eugenol, but lacks both estragole and methyl eugenol, had apparently no allylphenol dependent O-methyltransferase activities. These results indicate the presence of at least two types of allylphenol-specific O-methyltransferase activities in sweet basil chemotypes, one highly specific for chavicol; and a different one that can accept eugenol as a substrate. The relative availability and substrate specificities of these O-methyltransferase activities biochemically rationalizes the variation in the composition of the essential oils of these chemotypes.
Cloning, expression, purification, crystallization and preliminary X-ray analysis of NodS N-methyltransferase from Bradyrhizobium japonicum WM9

International Nuclear Information System (INIS)

Cakici, Ozgur; Sikorski, Michal; Stepkowski, Tomasz; Bujacz, Grzegorz; Jaskolski, Mariusz

2008-01-01

The NodS N-methyltransferase, an enzyme participating in the biosynthesis of the bacterial nodulation (Nod) factor necessary to establish symbiotic nitrogen fixation with a legume plant host, has been crystallized in the apo form as well as in complex with SAH. SAH is a byproduct of SAM degradation during the SAM-dependent methylation reaction. The Nod factor (NF) is a rhizobial signal molecule that is involved in recognition of a legume host and the formation of root and stem nodules. Some unique enzymes are involved in the biosynthesis of NF, which is a variously but specifically substituted lipochitooligosaccharide. One of these enzymes is NodS, an N-methyltransferase that methylates end-deacetylated chitooligosaccharide substrates. In the methylation reaction, NodS uses S-adenosyl-l-methionine (SAM) as a methyl donor. To date, no structural information is available about NodS from any rhizobium. X-ray crystallographic studies of the NodS protein from Bradyrhizobium japonicum WM9, which infects the legumes lupin and serradella, have been undertaken. The nodS gene was cloned and the recombinant protein was expressed in Escherichia coli cells using natural amino acids and as an SeMet derivative. NodS without ligands was crystallized in the presence of PEG 3350 and MgCl 2 . The protein was also crystallized in complex with S-adenosyl-l-homocysteine (SAH) in the presence of PEG 8000 and MgCl 2 . SAH is produced from SAM as a byproduct of the methylation reaction. The crystals of apo NodS are tetragonal and diffracted X-rays to 2.42 Å resolution. The NodS–SAH complex crystallizes in an orthorhombic space group and the crystals diffracted X-rays to 1.85 Å resolution
Enzymatic methylation of band 3 anion transporter in intact human erythrocytes

International Nuclear Information System (INIS)

Lou, L.L.; Clarke, S.

1987-01-01

Band 3, the anion transport protein of erythrocyte membranes, is a major methyl-accepting substrate of the intracellular erythrocyte protein carboxyl methyltransferase (S-adenosyl-L-methionine: protein-D-aspartate O-methyltransferase; EC 2.1.1.77). The localization of methylation sites in intact cells by analysis of proteolytic fragments indicated that sites were present in the cytoplasmic N-terminal domain as well as the membranous C-terminal portion of the polypeptide. The amino acid residues that serve as carboxyl methylation sites of the erythrocyte anion transporter were also investigated. 3 H-Methylated band 3 was purified from intact erythrocytes incubated with L-[methyl- 3 H]methionine and from trypsinized and lysed erythrocytes incubated with S-adenosyl-L-[methyl- 3 H]methionine. After proteolytic digestion with carboxypeptidase Y, D-aspartic acid beta-[ 3 H]methyl ester was isolated in low yields (9% and 1%, respectively) from each preparation. The bulk of the radioactivity was recovered as [ 3 H]methanol, and the amino acid residue(s) originally associated with these methyl groups could not be determined. No L-aspartic acid beta-[ 3 H]methyl ester or glutamyl gamma-[ 3 H]methyl ester was detected. The formation of D-aspartic acid beta-[ 3 H]methyl esters in this protein in intact cells resulted from protein carboxyl methyltransferase activity since it was inhibited by adenosine and homocysteine thiolactone, which increases the intracellular concentration of the potent product inhibitor S-adenosylhomocysteine, and cycloleucine, which prevents the formation of the substrate S-adenosyl-L-[methyl- 3 H]methionine
A novel double-isotope technique for the enzymatic assay of plasma histamine: application to estimation of mast cell activation assessed by antigen challenge in asthmatics

International Nuclear Information System (INIS)

Brown, M.J.; Ind, P.W.; Causon, R.; Lee, T.H.

1982-01-01

The concentration of plasma histamine may provide an index of mast cell activation (degranulation) and can be measured by a sensitive radioenzymatic assay based on its specific conversion to (/sup 3/H)-methylhistamine in the presence of histamine-N-methyltransferase and (/sup 3/H)-S-adenosyl-L-methionine. In this assay, the separation of excess (/sup 3/H)-S-adenosyl-L-methionine from (/sup 3/H)-methylhistamine requires several steps, for which a correction factors is necessary to maintain precision. In the present modification, duplicate 50-microliters aliquots of each plasma sample were incubated with histamine-N-methyltransferase and (/sup 3/H)-S-adenosyl-L-methionine. A further aliquot, with an added standard of 200 ng/ml histamine, was incubated with histamine-N-methyl-transferase and (/sup 14/C)-S-adenosyl-L-methionine. This standard was converted to (/sup 14/C)-methylhistamine, and its recovery at the end of the assay corrected both for varying efficiency of methylation among plasma samples and for losses during the subsequent extraction and separation stages. The sensitivity of the assay was 25 pg/ml. The intra-assay and interassay coefficients of variation were 7.2% and 11.6%, respectively. In five asthmatics, antigen challenge caused a 28% fall in FEV1, and this was associated with a twofold to threefold rise in plasma histamine concentration. This assay may thus prove a useful method for assessing the role of mast cell release of mediators in vivo
Determination of free and conjugated catecholamines and L-3,4-dihydroxyphenylalanine in plasma and urine: evidence for a catechol-O-methyltransferase inhibitor in uraemia

International Nuclear Information System (INIS)

Demassieux, S.; Corneille, L.; Lachance, S.; Carriere, S.

1981-01-01

A sensitive, accurate and reproducible method has been developed for the determination of free and conjugated catecholamines and L-3,4-dihydroxyphenylalanine in plasma and urine. The assay involves the enzymatic conversion of these compounds to their radio-labelled O-methylated derivatives using catechol-O-methyltransferase and S-adenosyl-L-[methyl- 3 H]methionine. Recoveries of 75 +- 5% for dopamine, 70 +- 5% for adrenaline and 65 +- 5% for noradrenaline were obtained. The sensitivities were 0.5 pg for adrenaline and noradrenaline and 5-7 pg for dopamine and dihydroxyphenylalanine. Measurements of conjugated catecholamines were performed after mild acid hydrolysis for 20 min at 95 0 C. During this procedure no degradation of the catecholamines was observed. This assay led to the discovery of a dialyzable factor in the plasma of chronic uraemic patients which inhibits catechol-O-methyltransferase activity in vitro. The mean 22% inhibition observed for unhydrolyzed plasma increased to 42% after hydrolysis. The identity of this inhibitor which exists as an inactive conjugated form, probably a sulphate ester, and its implication in physiopathological disorders remain to be established. (Auth.)

Identification of Aquifex aeolicus tRNA (m2(2G26) methyltransferase gene.

Science.gov (United States)

Takeda, Hiroshi; Hori, Hiroyuki; Endo, Yaeta

2002-01-01

The modifications of N2,N2-dimethylguanine (m2(2)G) are found in tRNAs and rRNAs from eukarya and archaea. In tRNAs, modification at position G26 is generated by tRNA (m2(2)G26) methyltransferase, which is encoded by the corresponding gene, trm1. This enzyme catalyzes the methyl-transfer from S-adenosyl-L-methionine to the semi-conserved residue, G26, via the intermediate modified base, m2G26. Recent genome sequencing project has been reported that the putative trm1 is encoded in the genome of Aquifex aeolicus, a hyper-thermophilic eubacterium as only one exception among eubacteria. In order to confirm whether this bacterial trm1 gene product is a real tRNA (m2(2)G26) methyltransferase or not, we expressed this protein by wheat germ in vitro cell-free translation system. Our biochemical analysis clearly showed that this gene product possessed tRNA (m2(2)G26) methyltransferase activity.
An Iterative O-Methyltransferase Catalyzes 1,11-Dimethylation of Aspergillus fumigatus Fumaric Acid Amides.

Science.gov (United States)

Kalb, Daniel; Heinekamp, Thorsten; Schieferdecker, Sebastian; Nett, Markus; Brakhage, Axel A; Hoffmeister, Dirk

2016-10-04

S-adenosyl-l-methionine (SAM)-dependent methyltransfer is a common biosynthetic strategy to modify natural products. We investigated the previously uncharacterized Aspergillus fumigatus methyltransferase FtpM, which is encoded next to the bimodular fumaric acid amide synthetase FtpA. Structure elucidation of two new A. fumigatus natural products, the 1,11-dimethyl esters of fumaryl-l-tyrosine and fumaryl-l-phenylalanine, together with ftpM gene disruption suggested that FtpM catalyzes iterative methylation. Final evidence that a single enzyme repeatedly acts on fumaric acid amides came from an in vitro biochemical investigation with recombinantly produced FtpM. Size-exclusion chromatography indicated that this methyltransferase is active as a dimer. As ftpA and ftpM homologues are found clustered in other fungi, we expect our work will help to identify and annotate natural product biosynthesis genes in various species. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
S-adenosyl-L-methionine protection of acetaminophen mediated oxidative stress and identification of hepatic 4-hydroxynonenal protein adducts by mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Brown, James Mike [Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Huntington, WV (United States); Kuhlman, Christopher [Southwest Environmental Health Sciences Center, Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona Health Sciences Center, Tucson, AZ (United States); Terneus, Marcus V. [Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Huntington, WV (United States); Labenski, Matthew T. [Southwest Environmental Health Sciences Center, Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona Health Sciences Center, Tucson, AZ (United States); Lamyaithong, Andre Benja; Ball, John G. [Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Huntington, WV (United States); Lau, Serrine S. [Southwest Environmental Health Sciences Center, Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona Health Sciences Center, Tucson, AZ (United States); Valentovic, Monica A., E-mail: Valentov@marshall.edu [Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Huntington, WV (United States)

2014-12-01

Acetaminophen (APAP) hepatotoxicity is protected by S-adenosyl-L-methionine (SAMe) treatment 1 hour (h) after APAP in C57/Bl6 mice. This study examined protein carbonylation as well as mitochondrial and cytosolic protein adduction by 4-hydroxynonenal (4-HNE) using mass spectrometry (MS) analysis. Additional studies investigated the leakage of mitochondrial proteins and 4-HNE adduction of these proteins. Male C57/Bl6 mice (n = 5/group) were divided into the following groups and treated as indicated: Veh (15 ml/kg water, ip), SAMe (1.25 mmol/kg, ip), APAP (250 mg/kg), and SAMe given 1 h after APAP (S + A). APAP toxicity was confirmed by an increase (p < 0.05) in plasma ALT (U/l) and liver weight/10 g body weight relative to the Veh, SAMe and S + A groups 4 h following APAP treatment. SAMe administered 1 h post-APAP partially corrected APAP hepatotoxicity as ALT and liver weight/10 g body weights were lower in the S + A group compared the APAP group. APAP induced leakage of the mitochondrial protein, carbamoyl phosphate synthase-1 (CPS-1) into the cytosol and which was reduced in the S + A group. SAMe further reduced the extent of APAP mediated 4-HNE adduction of CPS-1. MS analysis of hepatic and mitochondrial subcellular fractions identified proteins from APAP treated mice. Site specific 4-HNE adducts were identified on mitochondrial proteins sarcosine dehydrogenase and carbamoyl phosphate synthase-1 (CPS-1). In summary, APAP is associated with 4-HNE adduction of proteins as identified by MS analysis and that CPS-1 leakage was greater in APAP treated mice. SAMe reduced the extent of 4-HNE adduction of proteins as well as leakage of CPS-1. - Highlights: • Acetaminophen (APAP) toxicity protected by S-adenosylmethionine (SAMe) • 4-Hydroxynonenal adducted to sarcosine dehydrogenase • 4-Hydroxynonenal adducted to carbamoyl phosphate synthetase-1 • SAMe reduced APAP mediated CPS-1 mitochondrial leakage.
S-adenosyl-L-methionine protection of acetaminophen mediated oxidative stress and identification of hepatic 4-hydroxynonenal protein adducts by mass spectrometry

International Nuclear Information System (INIS)

Brown, James Mike; Kuhlman, Christopher; Terneus, Marcus V.; Labenski, Matthew T.; Lamyaithong, Andre Benja; Ball, John G.; Lau, Serrine S.; Valentovic, Monica A.

2014-01-01

Acetaminophen (APAP) hepatotoxicity is protected by S-adenosyl-L-methionine (SAMe) treatment 1 hour (h) after APAP in C57/Bl6 mice. This study examined protein carbonylation as well as mitochondrial and cytosolic protein adduction by 4-hydroxynonenal (4-HNE) using mass spectrometry (MS) analysis. Additional studies investigated the leakage of mitochondrial proteins and 4-HNE adduction of these proteins. Male C57/Bl6 mice (n = 5/group) were divided into the following groups and treated as indicated: Veh (15 ml/kg water, ip), SAMe (1.25 mmol/kg, ip), APAP (250 mg/kg), and SAMe given 1 h after APAP (S + A). APAP toxicity was confirmed by an increase (p < 0.05) in plasma ALT (U/l) and liver weight/10 g body weight relative to the Veh, SAMe and S + A groups 4 h following APAP treatment. SAMe administered 1 h post-APAP partially corrected APAP hepatotoxicity as ALT and liver weight/10 g body weights were lower in the S + A group compared the APAP group. APAP induced leakage of the mitochondrial protein, carbamoyl phosphate synthase-1 (CPS-1) into the cytosol and which was reduced in the S + A group. SAMe further reduced the extent of APAP mediated 4-HNE adduction of CPS-1. MS analysis of hepatic and mitochondrial subcellular fractions identified proteins from APAP treated mice. Site specific 4-HNE adducts were identified on mitochondrial proteins sarcosine dehydrogenase and carbamoyl phosphate synthase-1 (CPS-1). In summary, APAP is associated with 4-HNE adduction of proteins as identified by MS analysis and that CPS-1 leakage was greater in APAP treated mice. SAMe reduced the extent of 4-HNE adduction of proteins as well as leakage of CPS-1. - Highlights: • Acetaminophen (APAP) toxicity protected by S-adenosylmethionine (SAMe) • 4-Hydroxynonenal adducted to sarcosine dehydrogenase • 4-Hydroxynonenal adducted to carbamoyl phosphate synthetase-1 • SAMe reduced APAP mediated CPS-1 mitochondrial leakage
Crystallization and preliminary crystallographic analysis of tRNA (m7G46) methyltransferase from Escherichia coli

International Nuclear Information System (INIS)

Liu, Qi; Gao, Yang; Yang, Weili; Zhou, Huihao; Gao, Yongxiang; Zhang, Xiao; Teng, Maikun; Niu, Liwen

2008-01-01

tRNA (m 7 G46) methyltransferase from E. coli was overexpressed, purified and crystallized. Diffraction data were collected to 2.04 Å resolution. Transfer RNA (tRNA) (m 7 G46) methyltransferase (TrmB) belongs to the Rossmann-fold methyltransferase (RFM) family and uses S-adenosyl-l-methionine (SAM) as the methyl-group donor to catalyze the formation of N 7 -methylguanosine (m 7 G) at position 46 in the variable loop of tRNAs. After attempts to crystallize full-length Escherichia coli TrmB (EcTrmB) failed, a truncated protein lacking the first 32 residues of the N-terminus but with an additional His 6 tag at the C-terminus was crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 3350 (PEG 3350) as precipitant at 283 K. An X-ray diffraction data set was collected using a single flash-cooled crystal that belonged to space group P2 1
Crystallization and preliminary crystallographic analysis of tRNA (m{sup 7}G46) methyltransferase from Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Liu, Qi; Gao, Yang; Yang, Weili; Zhou, Huihao; Gao, Yongxiang; Zhang, Xiao; Teng, Maikun, E-mail: mkteng@ustc.edu.cn; Niu, Liwen, E-mail: mkteng@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230027 (China); Key Laboratory of Structural Biology, Chinese Academy of Sciences, 96 Jinzhai Road, Hefei, Anhui 230027 (China)

2008-08-01

tRNA (m{sup 7}G46) methyltransferase from E. coli was overexpressed, purified and crystallized. Diffraction data were collected to 2.04 Å resolution. Transfer RNA (tRNA) (m{sup 7}G46) methyltransferase (TrmB) belongs to the Rossmann-fold methyltransferase (RFM) family and uses S-adenosyl-l-methionine (SAM) as the methyl-group donor to catalyze the formation of N{sup 7}-methylguanosine (m{sup 7}G) at position 46 in the variable loop of tRNAs. After attempts to crystallize full-length Escherichia coli TrmB (EcTrmB) failed, a truncated protein lacking the first 32 residues of the N-terminus but with an additional His{sub 6} tag at the C-terminus was crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 3350 (PEG 3350) as precipitant at 283 K. An X-ray diffraction data set was collected using a single flash-cooled crystal that belonged to space group P2{sub 1}.
Early diagnosis of adenylosuccinate lyase deficiency using a high-throughput screening method and a trial of oral S-adenosyl-l-methionine as a treatment method.

Science.gov (United States)

van Werkhoven, Michiel A; Duley, John A; McGown, Ivan; Munce, Teresa; Freeman, Jeremy L; Pitt, James J

2013-11-01

The aim of this study was to develop a high-throughput urine screening technique for adenylosuccinate lyase (ADSL) deficiency and to evaluate S-adenosyl-l-methionine (SAMe) as a potential treatment for this disorder. Testing for succinyladenosine (S-Ado), a marker of ADSL deficiency, was incorporated into a screening panel for urine biomarkers for inborn errors of metabolism using electrospray tandem mass spectrometry. Liquid chromatography-mass spectrometry and high-performance liquid chromatography were used to confirm and monitor the response of metabolites to oral SAMe treatment. Increased levels of S-Ado were detected in a 3-month-old male infant with hypotonia and seizures. ADSL gene sequencing revealed a previously described c.-49T>C mutation and a novel c.889_891dupAAT mutation, which was likely to disrupt enzyme function. After 9 months of SAMe treatment, there was no clear response evidenced in urine metabolite levels or clinical parameters. These results demonstrate proof of the principle for the high-throughput urine screening technique, allowing earlier diagnosis of patients with ADSL deficiency. However, early treatment with SAMe does not appear to be effective in ADSL deficiency. It is suggested that although SAMe treatment may ameliorate purine nucleotide deficiency, it cannot correct metabolic syndromes in which a toxic nucleotide is present, in this case presumed to be succinylaminoimidazole carboxamide ribotide. © 2013 Mac Keith Press.
Evaluation of S-adenosyl l-methionine in a double-blinded, randomized, placebo-controlled, clinical trial for treatment of presumptive osteoarthritis in the dog.

Science.gov (United States)

Imhoff, Darren J; Gordon-Evans, Wanda J; Evans, Richard B; Johnson, Ann L; Griffon, Dominique J; Swanson, Kelly S

2011-02-01

To evaluate the efficacy of S-adenosyl l-methionine (SAMe) in the treatment of clinically inferred canine osteoarthritis (OA). Six weeks, double-blinded, placebo-controlled, clinical trial. Dogs (n=33) with clinical signs, history, and orthopedic exams consistent with OA. Dogs were block randomized by body condition score (goniometry, and the Canine Brief Pain Inventory (CBPI) at the time of study entrance and at 3 and 6 weeks after entry. Groups were compared using parametric and nonparametric paired tests as appropriate, and numbers needed to treat (NNT) were calculated for the CBPI and peak vertical force (PVF). Both groups (n=15 placebo, n=18 SAMe) had a reduction in mean PVF (P=.02) and vertical impulse (VI; P=.06) from the 1st to 3rd visit. There was no significant difference between the placebo group and SAMe group for PVF, VI, or either part of the CBPI (Severity or Impact). The NNT at 6 weeks for the Severity score was 3, Impact score was 25, and PVF was 45. These data do not support the use of SAMe as an effective stand alone treatment for reducing clinical signs of OA, as measured by PVF, VI, goniometry, CBPI (both Severity and Impact), and examination score within 6 weeks of treatment. © Copyright 2011 by The American College of Veterinary Surgeons.
Conversion of nicotinic acid to trigonelline is catalyzed by N-methyltransferase belonged to motif B′ methyltransferase family in Coffea arabica

International Nuclear Information System (INIS)

Mizuno, Kouichi; Matsuzaki, Masahiro; Kanazawa, Shiho; Tokiwano, Tetsuo; Yoshizawa, Yuko; Kato, Misako

2014-01-01

Graphical abstract: Trigonelline synthase catalyzes the conversion of nicotinic acid to trigonelline. We isolated and characterized trigonelline synthase gene(s) from Coffea arabica. - Highlights: • Trigonelline is a major compound in coffee been same as caffeine is. • We isolated and characterized trigonelline synthase gene. • Coffee trigonelline synthases are highly homologous with coffee caffeine synthases. • This study contributes the fully understanding of pyridine alkaloid metabolism. - Abstract: Trigonelline (N-methylnicotinate), a member of the pyridine alkaloids, accumulates in coffee beans along with caffeine. The biosynthetic pathway of trigonelline is not fully elucidated. While it is quite likely that the production of trigonelline from nicotinate is catalyzed by N-methyltransferase, as is caffeine synthase (CS), the enzyme(s) and gene(s) involved in N-methylation have not yet been characterized. It should be noted that, similar to caffeine, trigonelline accumulation is initiated during the development of coffee fruits. Interestingly, the expression profiles for two genes homologous to caffeine synthases were similar to the accumulation profile of trigonelline. We presumed that these two CS-homologous genes encoded trigonelline synthases. These genes were then expressed in Escherichiacoli, and the resulting recombinant enzymes that were obtained were characterized. Consequently, using the N-methyltransferase assay with S-adenosyl[methyl- 14 C]methionine, it was confirmed that these recombinant enzymes catalyzed the conversion of nicotinate to trigonelline, coffee trigonelline synthases (termed CTgS1 and CTgS2) were highly identical (over 95% identity) to each other. The sequence homology between the CTgSs and coffee CCS1 was 82%. The pH-dependent activity curve of CTgS1 and CTgS2 revealed optimum activity at pH 7.5. Nicotinate was the specific methyl acceptor for CTgSs, and no activity was detected with any other nicotinate derivatives, or with
Conversion of nicotinic acid to trigonelline is catalyzed by N-methyltransferase belonged to motif B′ methyltransferase family in Coffea arabica

Energy Technology Data Exchange (ETDEWEB)

Mizuno, Kouichi, E-mail: koumno@akita-pu.ac.jp [Faculty of Bioresource Sciences, Akita Prefectural University, Akita City, Akita 010-0195 (Japan); Matsuzaki, Masahiro [Faculty of Bioresource Sciences, Akita Prefectural University, Akita City, Akita 010-0195 (Japan); Kanazawa, Shiho [Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610 (Japan); Tokiwano, Tetsuo; Yoshizawa, Yuko [Faculty of Bioresource Sciences, Akita Prefectural University, Akita City, Akita 010-0195 (Japan); Kato, Misako [Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610 (Japan)

2014-10-03

Graphical abstract: Trigonelline synthase catalyzes the conversion of nicotinic acid to trigonelline. We isolated and characterized trigonelline synthase gene(s) from Coffea arabica. - Highlights: • Trigonelline is a major compound in coffee been same as caffeine is. • We isolated and characterized trigonelline synthase gene. • Coffee trigonelline synthases are highly homologous with coffee caffeine synthases. • This study contributes the fully understanding of pyridine alkaloid metabolism. - Abstract: Trigonelline (N-methylnicotinate), a member of the pyridine alkaloids, accumulates in coffee beans along with caffeine. The biosynthetic pathway of trigonelline is not fully elucidated. While it is quite likely that the production of trigonelline from nicotinate is catalyzed by N-methyltransferase, as is caffeine synthase (CS), the enzyme(s) and gene(s) involved in N-methylation have not yet been characterized. It should be noted that, similar to caffeine, trigonelline accumulation is initiated during the development of coffee fruits. Interestingly, the expression profiles for two genes homologous to caffeine synthases were similar to the accumulation profile of trigonelline. We presumed that these two CS-homologous genes encoded trigonelline synthases. These genes were then expressed in Escherichiacoli, and the resulting recombinant enzymes that were obtained were characterized. Consequently, using the N-methyltransferase assay with S-adenosyl[methyl-{sup 14}C]methionine, it was confirmed that these recombinant enzymes catalyzed the conversion of nicotinate to trigonelline, coffee trigonelline synthases (termed CTgS1 and CTgS2) were highly identical (over 95% identity) to each other. The sequence homology between the CTgSs and coffee CCS1 was 82%. The pH-dependent activity curve of CTgS1 and CTgS2 revealed optimum activity at pH 7.5. Nicotinate was the specific methyl acceptor for CTgSs, and no activity was detected with any other nicotinate derivatives, or
Metabolism of S-adenosylmethionine in rat hepatocytes: transfer of methyl group from S-adenosylmethionine by methyltransferase reactions

International Nuclear Information System (INIS)

Tsukada, K.; Abe, T.; Kuwahata, T.; Mitsui, K.

1985-01-01

Treatment of rats with a methionine diet leads not only to a marked increase of S-adenosylmethionine synthetase in liver, but also to the increase of glycine, guanidoacetate and betaine-homocysteine methyltransferases. The activity of tRNA methyltransferase decreased with the increased amounts of methionine in the diets. However, the activities of phospholipids and S-adenosylmethionine-homocysteine methyltransferases did not show any significant change. When hepatocarcinogenesis induced by 2-fluorenylacetamide progresses, the activities of glycine and guanidoacetate methyltransferases in rat liver decreased, and could not be detected in tumorous areas 8 months after treatment. The levels of S-adenosylmethionine in the liver also decreased to levels of one-fifth of control animals at 8 months. The uptake and metabolism of [methyl- 3 H]-methionine and -S-adenosylmethionine have been investigated by in vivo and isolated hepatocytes. The uptake of methionine and transfer of methyl group to phospholipid in the cells by methionine were remarkably higher than those by S-adenosylmethionine. These results indicate that phospholipids in hepatocytes accept methyl group from S-adenosylmethionine immediately, when it is synthesized from methionine, before mixing its pool in the cells. 39 references, 1 figure, 2 tables
4-Demethylwyosine Synthase from Pyrococcus abyssi Is a Radical-S-adenosyl-l-methionine Enzyme with an Additional [4Fe-4S]+2 Cluster That Interacts with the Pyruvate Co-substrate*

Science.gov (United States)

Perche-Letuvée, Phanélie; Kathirvelu, Velavan; Berggren, Gustav; Clemancey, Martin; Latour, Jean-Marc; Maurel, Vincent; Douki, Thierry; Armengaud, Jean; Mulliez, Etienne; Fontecave, Marc; Garcia-Serres, Ricardo; Gambarelli, Serge; Atta, Mohamed

2012-01-01

Wybutosine and its derivatives are found in position 37 of tRNA encoding Phe in eukaryotes and archaea. They are believed to play a key role in the decoding function of the ribosome. The second step in the biosynthesis of wybutosine is catalyzed by TYW1 protein, which is a member of the well established class of metalloenzymes called “Radical-SAM.” These enzymes use a [4Fe-4S] cluster, chelated by three cysteines in a CX3CX2C motif, and S-adenosyl-l-methionine (SAM) to generate a 5′-deoxyadenosyl radical that initiates various chemically challenging reactions. Sequence analysis of TYW1 proteins revealed, in the N-terminal half of the enzyme beside the Radical-SAM cysteine triad, an additional highly conserved cysteine motif. In this study we show by combining analytical and spectroscopic methods including UV-visible absorption, Mössbauer, EPR, and HYSCORE spectroscopies that these additional cysteines are involved in the coordination of a second [4Fe-4S] cluster displaying a free coordination site that interacts with pyruvate, the second substrate of the reaction. The presence of two distinct iron-sulfur clusters on TYW1 is reminiscent of MiaB, another tRNA-modifying metalloenzyme whose active form was shown to bind two iron-sulfur clusters. A possible role for the second [4Fe-4S] cluster in the enzyme activity is discussed. PMID:23043105
The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells.

Science.gov (United States)

Suriguga; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun

2013-12-15

Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation. © 2013.
Preliminary characterization of (nucleoside-2′-O-)-methyltransferase crystals from Meaban and Yokose flaviviruses

International Nuclear Information System (INIS)

Mastrangelo, Eloise; Bollati, Michela; Milani, Mario; Lamballeire, Xavier de; Brisbare, Nadege; Dalle, Karen; Lantez, Violaine; Egloff, Marie-Pierre; Coutard, Bruno; Canard, Bruno; Gould, Ernest; Forrester, Naomi; Bolognesi, Martino

2006-01-01

Two methyltransferases from flaviviruses (Meaban and Yokose viruses) have been overexpressed and crystallized. Diffraction data and characterization of the two crystal forms are presented, together with a preliminary molecular-replacement solution for both enzymes. Viral methyltranferases (MTase) are involved in the third step of the mRNA-capping process, transferring a methyl group from S-adenosyl-l-methionine (SAM) to the capped mRNA. MTases are classified into two groups: (guanine-N7)-methyltransferases (N7MTases), which add a methyl group onto the N7 atom of guanine, and (nucleoside-2′-O-)-methyltransferases (2′OMTases), which add a methyl group to a ribose hydroxyl. The MTases of two flaviviruses, Meaban and Yokose viruses, have been overexpressed, purified and crystallized in complex with SAM. Characterization of the crystals together with details of preliminary X-ray diffraction data collection (at 2.8 and 2.7 Å resolution, respectively) are reported here. The sequence homology relative to Dengue virus 2′OMTase and the structural conservation of specific residues in the putative active sites suggest that both enzymes belong to the 2′OMTase subgroup
Preliminary characterization of (nucleoside-2′-O-)-methyltransferase crystals from Meaban and Yokose flaviviruses

Energy Technology Data Exchange (ETDEWEB)

Mastrangelo, Eloise; Bollati, Michela; Milani, Mario [Department of Biomolecular Sciences and Biotechnology, CNR-INFM, University of Milano, Via Celoria 26, 20133 Milano (Italy); Lamballeire, Xavier de; Brisbare, Nadege [Unité des Virus Emergents, Faculté de Médecine, 27 Boulevard Jean Moulin, 13005 Marseille (France); Dalle, Karen; Lantez, Violaine; Egloff, Marie-Pierre; Coutard, Bruno; Canard, Bruno [Laboratoire Architecture et Fonction des Macromolécules Biologiques, UMR 6098 CNRS ESIL, Case 932, 163 Avenue de Luminy, 13288 Marseille CEDEX 9 (France); Gould, Ernest; Forrester, Naomi [CEH Oxford, Mansfield Road, Oxford OX1 3SR (United Kingdom); Bolognesi, Martino, E-mail: martino.bolognesi@unimi.it [Department of Biomolecular Sciences and Biotechnology, CNR-INFM, University of Milano, Via Celoria 26, 20133 Milano (Italy)

2006-08-01

Two methyltransferases from flaviviruses (Meaban and Yokose viruses) have been overexpressed and crystallized. Diffraction data and characterization of the two crystal forms are presented, together with a preliminary molecular-replacement solution for both enzymes. Viral methyltranferases (MTase) are involved in the third step of the mRNA-capping process, transferring a methyl group from S-adenosyl-l-methionine (SAM) to the capped mRNA. MTases are classified into two groups: (guanine-N7)-methyltransferases (N7MTases), which add a methyl group onto the N7 atom of guanine, and (nucleoside-2′-O-)-methyltransferases (2′OMTases), which add a methyl group to a ribose hydroxyl. The MTases of two flaviviruses, Meaban and Yokose viruses, have been overexpressed, purified and crystallized in complex with SAM. Characterization of the crystals together with details of preliminary X-ray diffraction data collection (at 2.8 and 2.7 Å resolution, respectively) are reported here. The sequence homology relative to Dengue virus 2′OMTase and the structural conservation of specific residues in the putative active sites suggest that both enzymes belong to the 2′OMTase subgroup.
Crystallization and preliminary X-ray crystallographic studies of O-methyltransferase from Anabaena PCC 7120

International Nuclear Information System (INIS)

Li, Guoming; Tang, Zhenting; Meng, Geng; Dai, Kesheng; Zhao, Jindong; Zheng, Xiaofeng

2009-01-01

The O-methyltransferase (OMT) from the Anabaena PCC 7120 has been overexpressed in a soluble form in E. coli, purified and crystallized. The crystals belonged to space group C222 1 and diffracted to 2.4 Å resolution. O-Methyltransferase (OMT) is a ubiquitous enzyme that exists in bacteria, plants and humans and catalyzes a methyl-transfer reaction using S-adenosyl-l-methionine as a methyl donor and a wide range of phenolics as acceptors. To investigate the structure and function of OMTs, omt from Anabaena PCC 7120 was cloned into expression vector pET21a and expressed in a soluble form in Escherichia coli strain BL21 (DE3). The recombinant OMT protein was purified to homogeneity using a two-step strategy. Crystals of OMT that diffracted to a resolution of 2.4 Å were obtained using the hanging-drop vapour-diffusion method. The crystals belonged to space group C222 1 , with unit-cell parameters a = 131.620, b = 227.994, c = 150.777 Å, α = β = γ = 90°. There are eight molecules per asymmetric unit
Molecular cloning and functional expression of a stress-induced multifunctional O-methyltransferase with pinosylvin methyltransferase activity from Scots pine (Pinus sylvestris L.).

Science.gov (United States)

Chiron, H; Drouet, A; Claudot, A C; Eckerskorn, C; Trost, M; Heller, W; Ernst, D; Sandermann, H

2000-12-01

Formation of pinosylvin (PS) and pinosylvin 3-O-monomethyl ether (PSM), as well as the activities of stilbene synthase (STS) and S-adenosyl-1-methionine (SAM):pinosylvin O-methyltransferase (PMT), were induced strongly in needles of Scots pine seedlings upon ozone treatment, as well as in cell suspension cultures of Scots pine upon fungal elicitation. A SAM-dependent PMT protein was purified and partially characterised. A cDNA encoding PMT was isolated from an ozone-induced Scots pine cDNA library. Southern blot analysis of the genomic DNA suggested the presence of a gene family. The deduced protein sequence showed the typical highly conserved regions of O-methyltransferases (OMTs), and average identities of 20-56% to known OMTs. PMT expressed in Escherichia coli corresponded to that of purified PMT (40 kDa) from pine cell cultures. The recombinant enzyme catalysed the methylation of PS, caffeic acid, caffeoyl-CoA and quercetin. Several other substances, such as astringenin, resveratrol, 5-OH-ferulic acid, catechol and luteolin, were also methylated. Recombinant PMT thus had a relatively broad substrate specificity. Treatment of 7-year old Scots pine trees with ozone markedly increased the PMT mRNA level. Our results show that PMT represents a new SAM-dependent OMT for the methylation of stress-induced pinosylvin in Scots pine needles.
Crystal structure of MboIIA methyltransferase.

Science.gov (United States)

Osipiuk, Jerzy; Walsh, Martin A; Joachimiak, Andrzej

2003-09-15

DNA methyltransferases (MTases) are sequence-specific enzymes which transfer a methyl group from S-adenosyl-L-methionine (AdoMet) to the amino group of either cytosine or adenine within a recognized DNA sequence. Methylation of a base in a specific DNA sequence protects DNA from nucleolytic cleavage by restriction enzymes recognizing the same DNA sequence. We have determined at 1.74 A resolution the crystal structure of a beta-class DNA MTase MboIIA (M.MboIIA) from the bacterium Moraxella bovis, the smallest DNA MTase determined to date. M.MboIIA methylates the 3' adenine of the pentanucleotide sequence 5'-GAAGA-3'. The protein crystallizes with two molecules in the asymmetric unit which we propose to resemble the dimer when M.MboIIA is not bound to DNA. The overall structure of the enzyme closely resembles that of M.RsrI. However, the cofactor-binding pocket in M.MboIIA forms a closed structure which is in contrast to the open-form structures of other known MTases.
Recognition of Ribosomal Protein L11 by the Protein Trimethyltransferase PrmA

Energy Technology Data Exchange (ETDEWEB)

Demirci,H.; Gregory, S.; Dahlberg, A.; Jogl, G.

2007-01-01

Bacterial ribosomal protein L11 is post-translationally trimethylated at multiple residues by a single methyltransferase, PrmA. Here, we describe four structures of PrmA from the extreme thermophile Thermus thermophilus. Two apo-PrmA structures at 1.59 and 2.3 {angstrom} resolution and a third with bound cofactor S-adenosyl-L-methionine at 1.75 {angstrom} each exhibit distinct relative positions of the substrate recognition and catalytic domains, revealing how PrmA can position the L11 substrate for multiple, consecutive side-chain methylation reactions. The fourth structure, the PrmA-L11 enzyme-substrate complex at 2.4 {angstrom} resolution, illustrates the highly specific interaction of the N-terminal domain with its substrate and places Lys39 in the PrmA active site. The presence of a unique flexible loop in the cofactor-binding site suggests how exchange of AdoMet with the reaction product S-adenosyl-L-homocysteine can occur without necessitating the dissociation of PrmA from L11. Finally, the mode of interaction of PrmA with L11 explains its observed preference for L11 as substrate before its assembly into the 50S ribosomal subunit.
A histone H3K9M mutation traps histone methyltransferase Clr4 to prevent heterochromatin spreading

Energy Technology Data Exchange (ETDEWEB)

Shan, Chun-Min; Wang, Jiyong; Xu, Ke; Chen, Huijie; Yue, Jia-Xing; Andrews, Stuart; Moresco, James J.; Yates, John R.; Nagy, Peter L.; Tong, Liang; Jia, Songtao

2016-09-20

Histone lysine-to-methionine (K-to-M) mutations are associated with multiple cancers, and they function in a dominant fashion to block the methylation of corresponding lysines on wild type histones. However, their mechanisms of function are controversial. Here we show that in fission yeast, introducing the K9M mutation into one of the three histone H3 genes dominantly blocks H3K9 methylation on wild type H3 across the genome. In addition, H3K9M enhances the interaction of histone H3 tail with the H3K9 methyltransferase Clr4 in a SAM (S-adenosyl-methionine)-dependent manner, and Clr4 is trapped at nucleation sites to prevent its spreading and the formation of large heterochromatin domains. We further determined the crystal structure of an H3K9M peptide in complex with human H3K9 methyltransferase G9a and SAM, which reveales that the methionine side chain had enhanced van der Waals interactions with G9a. Therefore, our results provide a detailed mechanism by which H3K9M regulates H3K9 methylation.

Crystal complexes of a predicted S-adenosylmethionine-dependent methyltransferase reveal a typical AdoMet binding domain and a substrate recognition domain

Energy Technology Data Exchange (ETDEWEB)

Miller, D.J.; Ouellette, N.; Evodokimova, E.; Savchenko, A.; Edwards, A.; Anderson, W.F. (Toronto); (NWU)

2010-03-08

S-adenosyl-L-methionine-dependent methyltransferases (MTs) are abundant, and highly conserved across phylogeny. These enzymes use the cofactor AdoMet to methylate a wide variety of molecular targets, thereby modulating important cellular and metabolic activities. Thermotoga maritima protein 0872 (TM0872) belongs to a large sequence family of predicted MTs, ranging phylogenetically from relatively simple bacteria to humans. The genes for many of the bacterial homologs are located within operons involved in cell wall synthesis and cell division. Despite preliminary biochemical studies in E. coli and B. subtilis, the substrate specificity of this group of more than 150 proteins is unknown. As part of the Midwest Center for Structural Genomics initiative (www.mcsg.anl.gov), we have determined the structure of TM0872 in complexes with AdoMet and with S-adenosyl-L-homocysteine (AdoHcy). As predicted, TM0872 has a typical MT domain, and binds endogenous AdoMet, or co-crystallized AdoHcy, in a manner consistent with other known MT structures. In addition, TM0872 has a second domain that is novel among MTs in both its location in the sequence and its structure. The second domain likely acts in substrate recognition and binding, and there is a potential substrate-binding cleft spanning the two domains. This long and narrow cleft is lined with positively charged residues which are located opposite the S{sup +}-CH{sub 3} bond, suggesting that a negatively charged molecule might be targeted for catalysis. However, AdoMet and AdoHcy are both buried, and access to the methyl group would presumably require structural rearrangement. These TM0872 crystal structures offer the first structural glimpses at this phylogenetically conserved sequence family.
The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells

Energy Technology Data Exchange (ETDEWEB)

Suriguga,; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun, E-mail: yizc@buaa.edu.cn

2013-12-15

Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation. - Highlights: • Catechol enhanced hemin-induced hemoglobin accumulation. • COMT-catalyzed methylation acted as detoxication of catechol. • COMT involved in catechol-enhanced erythroid differentiation.
The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells

International Nuclear Information System (INIS)

Suriguga,; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun

2013-01-01

Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation. - Highlights: • Catechol enhanced hemin-induced hemoglobin accumulation. • COMT-catalyzed methylation acted as detoxication of catechol. • COMT involved in catechol-enhanced erythroid differentiation
Structural Basis of Substrate Recognition in Human Nicotinamide N-Methyltransferase

Energy Technology Data Exchange (ETDEWEB)

Peng, Yi; Sartini, Davide; Pozzi, Valentina; Wilk, Dennis; Emanuelli, Monica; Yee, Vivien C. (Case Western); (Politecnica Valencia)

2012-05-02

Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation of nicotinamide, pyridines, and other analogues using S-adenosyl-L-methionine as donor. NNMT plays a significant role in the regulation of metabolic pathways and is expressed at markedly high levels in several kinds of cancers, presenting it as a potential molecular target for cancer therapy. We have determined the crystal structure of human NNMT as a ternary complex bound to both the demethylated donor S-adenosyl-L-homocysteine and the acceptor substrate nicotinamide, to 2.7 {angstrom} resolution. These studies reveal the structural basis for nicotinamide binding and highlight several residues in the active site which may play roles in nicotinamide recognition and NNMT catalysis. The functional importance of these residues was probed by mutagenesis. Of three residues near the nicotinamide's amide group, substitution of S201 and S213 had no effect on enzyme activity while replacement of D197 dramatically decreased activity. Substitutions of Y20, whose side chain hydroxyl interacts with both the nicotinamide aromatic ring and AdoHcy carboxylate, also compromised activity. Enzyme kinetics analysis revealed k{sub cat}/K{sub m} decreases of 2-3 orders of magnitude for the D197A and Y20A mutants, confirming the functional importance of these active site residues. The mutants exhibited substantially increased K{sub m} for both NCA and AdoMet and modestly decreased k{sub cat}. MD simulations revealed long-range conformational effects which provide an explanation for the large increase in K{sub m}(AdoMet) for the D197A mutant, which interacts directly only with nicotinamide in the ternary complex crystal structure.
The relative contribution of genes operating in the S-methylmethionine cycle to methionine metabolism in Arabidopsis seeds.

Science.gov (United States)

Cohen, Hagai; Salmon, Asaf; Tietel, Zipora; Hacham, Yael; Amir, Rachel

2017-05-01

Enzymes operating in the S -methylmethionine cycle make a differential contribution to methionine synthesis in seeds. In addition, mutual effects exist between the S -methylmethionine cycle and the aspartate family pathway in seeds. Methionine, a sulfur-containing amino acid, is a key metabolite in plant cells. The previous lines of evidence proposed that the S-methylmethionine (SMM) cycle contributes to methionine synthesis in seeds where methionine that is produced in non-seed tissues is converted to SMM and then transported via the phloem into the seeds. However, the relative regulatory roles of the S-methyltransferases operating within this cycle in seeds are yet to be fully understood. In the current study, we generated transgenic Arabidopsis seeds with altered expression of three HOMOCYSTEINE S-METHYLTRANSFERASEs (HMTs) and METHIONINE S-METHYLTRANSFERASE (MMT), and profiled them for transcript and metabolic changes. The results revealed that AtHMT1 and AtHMT3, but not AtHMT2 and AtMMT, are the predominant enzymes operating in seeds as altered expression of these two genes affected the levels of methionine and SMM in transgenic seeds. Their manipulations resulted in adapted expression level of genes participating in methionine synthesis through the SMM and aspartate family pathways. Taken together, our findings provide new insights into the regulatory roles of the SMM cycle and the mutual effects existing between the two methionine biosynthesis pathways, highlighting the complexity of the metabolism of methionine and SMM in seeds.
A New Structural Form in the SAM/Metal-Dependent O;#8209;Methyltransferase Family: MycE from the Mycinamicin Biosynthetic Pathway

Energy Technology Data Exchange (ETDEWEB)

Akey, David L.; Li, Shengying; Konwerski, Jamie R.; Confer, Laura A.; Bernard, Steffen M.; Anzai, Yojiro; Kato, Fumio; Sherman, David H.; Smith, Janet L. (Michigan); (Toho)

2012-08-01

O-linked methylation of sugar substituents is a common modification in the biosynthesis of many natural products and is catalyzed by multiple families of S-adenosyl-l-methionine (SAM or AdoMet)-dependent methyltransferases (MTs). Mycinamicins, potent antibiotics from Micromonospora griseorubida, can be methylated at two positions on a 6-deoxyallose substituent. The first methylation is catalyzed by MycE, a SAM- and metal-dependent MT. Crystal structures were determined for MycE bound to the product S-adenosyl-l-homocysteine (AdoHcy) and magnesium, both with and without the natural substrate mycinamicin VI. This represents the first structure of a natural product sugar MT in complex with its natural substrate. MycE is a tetramer of a two-domain polypeptide, comprising a C-terminal catalytic MT domain and an N-terminal auxiliary domain, which is important for quaternary assembly and for substrate binding. The symmetric MycE tetramer has a novel MT organization in which each of the four active sites is formed at the junction of three monomers within the tetramer. The active-site structure supports a mechanism in which a conserved histidine acts as a general base, and the metal ion helps to position the methyl acceptor and to stabilize a hydroxylate intermediate. A conserved tyrosine is suggested to support activity through interactions with the transferred methyl group from the SAM methyl donor. The structure of the free enzyme reveals a dramatic order-disorder transition in the active site relative to the S-adenosyl-L-homocysteine complexes, suggesting a mechanism for product/substrate exchange through concerted movement of five loops and the polypeptide C-terminus.
Insights into the reactivation of cobalamin-dependent methionine synthase

Energy Technology Data Exchange (ETDEWEB)

Koutmos, Markos; Datta, Supratim; Pattridge, Katherine A.; Smith, Janet L.; Matthews, Rowena G.; (Michigan)

2009-12-10

Cobalamin-dependent methionine synthase (MetH) is a modular protein that catalyzes the transfer of a methyl group from methyltetrahydrofolate to homocysteine to produce methionine and tetrahydrofolate. The cobalamin cofactor, which serves as both acceptor and donor of the methyl group, is oxidized once every {approx}2,000 catalytic cycles and must be reactivated by the uptake of an electron from reduced flavodoxin and a methyl group from S-adenosyl-L-methionine (AdoMet). Previous structures of a C-terminal fragment of MetH (MetH{sup CT}) revealed a reactivation conformation that juxtaposes the cobalamin- and AdoMet-binding domains. Here we describe 2 structures of a disulfide stabilized MetH{sup CT} ({sub s-s}MetH{sup CT}) that offer further insight into the reactivation of MetH. The structure of {sub s-s}MetH{sup CT} with cob(II)alamin and S-adenosyl-L-homocysteine represents the enzyme in the reactivation step preceding electron transfer from flavodoxin. The structure supports earlier suggestions that the enzyme acts to lower the reduction potential of the Co(II)/Co(I) couple by elongating the bond between the cobalt and its upper axial water ligand, effectively making the cobalt 4-coordinate, and illuminates the role of Tyr-1139 in the stabilization of this 4-coordinate state. The structure of {sub s-s}MetH{sub CT} with aquocobalamin may represent a transient state at the end of reactivation as the newly remethylated 5-coordinate methylcobalamin returns to the 6-coordinate state, triggering the rearrangement to a catalytic conformation.
Multiple-Site Trimethylation of Ribosomal Protein L11 by the PrmA Methyltransferase

Energy Technology Data Exchange (ETDEWEB)

Demirci,H.; Gregory, S.; Dahlberg, A.; Jogl, G.

2008-01-01

Ribosomal protein L11 is a universally conserved component of the large subunit, and plays a significant role during initiation, elongation, and termination of protein synthesis. In Escherichia coli, the lysine methyltransferase PrmA trimethylates the N-terminal a-amino group and the -amino groups of Lys3 and Lys39. Here, we report four PrmA-L11 complex structures in different orientations with respect to the PrmA active site. Two structures capture the L11 N-terminal a-amino group in the active site in a trimethylated postcatalytic state and in a dimethylated state with bound S-adenosyl-L-homocysteine. Two other structures show L11 in a catalytic orientation to modify Lys39 and in a noncatalytic orientation. The comparison of complex structures in different orientations with a minimal substrate recognition complex shows that the binding mode remains conserved in all L11 orientations, and that substrate orientation is brought about by the unusual interdomain flexibility of PrmA.
Determination of plasma adrenaline and noradrenaline levels with the Cat-a-Kit

International Nuclear Information System (INIS)

Nel, P.B.; Du Preez, S.E.

1980-01-01

A method for the determination of catecholamines (Cat-a-Kit; Upjohn Diagnostics) is discussed. It depends upon the enzymatic conversion of the catecholamines to their ring o-methylated analogues in the presence of s-adenosyl-L-methionine-methyl- 14 C and catechol-o-methyltransferase. Values obtained from the blood plasma of 16 tetraplegic and 11 healthy volunteers are reported. The advantages and disadvantages of the Cat-a-Kit are discussed
Evolution of the key alkaloid enzyme putrescine N-methyltransferase from spermidine synthase.

Directory of Open Access Journals (Sweden)

Anne eJunker

2013-07-01

Full Text Available Putrescine N-methyltransferases (PMTs are the first specific enzymes of the biosynthesis of nicotine and tropane alkaloids. PMTs transfer a methyl group onto the diamine putrescine from S-adenosyl-L-methionine (SAM as coenzyme. PMT proteins have presumably evolved from spermidine synthases (SPDSs, which are ubiquitous enzymes of polyamine metabolism. SPDS use decarboxylated SAM as coenzyme to transfer an aminopropyl group onto putrescine. In an attempt to identify possible and necessary steps in the evolution of PMT from SPDS, homology based modeling of Datura stramonium SPDS1 and PMT was employed to gain deeper insight in the preferred binding positions and conformations of the substrate and the alternative coenzymes. Based on predictions of amino acids responsible for the change of enzyme specificities, sites of mutagenesis were derived. PMT activity was generated in Datura stramonium SPDS1 after few amino acid exchanges. Concordantly, Arabidopsis thaliana SPDS1 was mutated and yielded enzymes with both, PMT and SPDS activities. Kinetic parameters were measured for enzymatic characterization. The switch from aminopropyl to methyl transfer depends on conformational changes of the methionine part of the coenzyme in the binding cavity of the enzyme. The rapid generation of PMT activity in SPDS proteins and the wide-spread occurrence of putative products of N-methylputrescine suggest that PMT activity is present frequently in the plant kingdom.
Cloning of a protein arginine methyltransferase PRMT1 homologue from Schistosoma mansoni: Evidence for roles in nuclear receptor signaling and RNA metabolism

International Nuclear Information System (INIS)

Mansure, Jose Joao; Furtado, Daniel Rodrigues; Bastos de Oliveira, Francisco Meirelles; Rumjanek, Franklin David; Franco, Gloria Regina; Fantappie, Marcelo Rosado

2005-01-01

The most studied arginine methyltransferase is the type I enzyme, which catalyzes the transfer of an S-adenosyl-L-methionine to a broad spectrum of substrates, including histones, RNA-transporting proteins, and nuclear hormone receptor coactivators. We cloned a cDNA encoding a protein arginine methyltransferase in Schistosoma mansoni (SmPRMT1). SmPRMT1 is highly homologous to the vertebrate PRMT1 enzyme. In vitro methylation assays showed that SmPRMT1 recombinant protein was able to specifically methylate histone H4. Two schistosome proteins likely to be involved in RNA metabolism, SMYB1 and SmSmD3, that display a number of RGG motifs, were strongly methylated by SmPRMT1. In vitro GST pull-down assays showed that SMYB1 and SmSmD3 physically interacted with SmPRMT1. Additional GST pull-down assay suggested the occurrence of a ternary complex including SmPRMT1, SmRXR1 nuclear receptor, and the p160 (SRC-1) nuclear receptor coactivator. Together, these data suggest a mechanism by which SmPRMT1 plays a role in nuclear receptor-mediated chromatin remodeling and RNA transactions
Noncompetitive inhibition of indolethylamine-N-methyltransferase by N,N-dimethyltryptamine and N,N-dimethylaminopropyltryptamine.

Science.gov (United States)

Chu, Uyen B; Vorperian, Sevahn K; Satyshur, Kenneth; Eickstaedt, Kelsey; Cozzi, Nicholas V; Mavlyutov, Timur; Hajipour, Abdol R; Ruoho, Arnold E

2014-05-13

Indolethylamine-N-methyltransferase (INMT) is a Class 1 transmethylation enzyme known for its production of N,N-dimethyltryptamine (DMT), a hallucinogen with affinity for various serotonergic, adrenergic, histaminergic, dopaminergic, and sigma-1 receptors. DMT is produced via the action of INMT on the endogenous substrates tryptamine and S-adenosyl-l-methionine (SAM). The biological, biochemical, and selective small molecule regulation of INMT enzyme activity remain largely unknown. Kinetic mechanisms for inhibition of rabbit lung INMT (rabINMT) by the product, DMT, and by a new novel tryptamine derivative were determined. After Michaelis-Menten and Lineweaver-Burk analyses had been applied to study inhibition, DMT was found to be a mixed competitive and noncompetitive inhibitor when measured against tryptamine. The novel tryptamine derivative, N-[2-(1H-indol-3-yl)ethyl]-N',N'-dimethylpropane-1,3-diamine (propyl dimethyl amino tryptamine or PDAT), was shown to inhibit rabINMT by a pure noncompetitive mechanism when measured against tryptamine with a Ki of 84 μM. No inhibition by PDAT was observed at 2 mM when it was tested against structurally similar Class 1 methyltransferases, such as human phenylethanolamine-N-methyltransferase (hPNMT) and human nicotinamide-N-methyltransferase (hNNMT), indicating selectivity for INMT. The demonstration of noncompetitive mechanisms for INMT inhibition implies the presence of an inhibitory allosteric site. In silico analyses using the computer modeling software Autodock and the rabINMT sequence threaded onto the human INMT (hINMT) structure (Protein Data Bank entry 2A14 ) identified an N-terminal helix-loop-helix non-active site binding region of the enzyme. The energies for binding of DMT and PDAT to this region of rabINMT, as determined by Autodock, were -6.34 and -7.58 kcal/mol, respectively. Assessment of the allosteric control of INMT may illuminate new biochemical pathway(s) underlying the biology of INMT.
Monolignol biosynthesis in microsomal preparations from lignifying stems of alfalfa (Medicago sativa L.).

Science.gov (United States)

Guo, Dianjing; Chen, Fang; Dixon, Richard A

2002-11-01

Microsomal preparations from lignifying stems of alfalfa (Medicago sativa L.) contained coniferaldehyde 5-hydroxylase activity and immunodetectable caffeic acid 3-O-methyltransferase (COMT), and catalyzed the S-adenosyl L-methionine (SAM) dependent methylation of caffeic acid, caffeyl aldehyde and caffeyl alcohol. When supplied with NADPH and SAM, the microsomes converted caffeyl aldehyde to coniferaldehyde, 5-hydroxyconiferaldehyde, and traces of sinapaldehyde. Coniferaldehyde was a better precursor of sinapaldehyde than was 5-hydroxyconiferaldehyde. The alfalfa microsomes could not metabolize 4-coumaric acid, 4-coumaraldehyde, 4-coumaroyl CoA, or ferulic acid. No metabolism of monolignol precursors was observed in microsomal preparations from transgenic alfalfa down-regulated in COMT expression. In most microsomal preparations, the level of the metabolic conversions was independent of added recombinant COMT. Taken together, the data provide only limited support for the concept of metabolic channeling in the biosynthesis of S monolignols via coniferaldehyde.
Conversion of a disulfide bond into a thioacetal group during echinomycin biosynthesis

Energy Technology Data Exchange (ETDEWEB)

Hotta, Kinya; Keegan, Ronan M.; Ranganathan, Soumya; Fang, Minyi; Bibby, Jaclyn; Winn, Martyn D.; Sato, Michio; Lian, Mingzhu; Watanabe, Kenji; Rigden, Daniel J.; Kim, Chu-Young (Liverpool); (Daresbury); (NU Singapore); (Shizuoka); (RAL)

2013-12-02

Echinomycin is a nonribosomal depsipeptide natural product with a range of interesting bioactivities that make it an important target for drug discovery and development. It contains a thioacetal bridge, a unique chemical motif derived from the disulfide bond of its precursor antibiotic triostin A by the action of an S-adenosyl-L-methionine-dependent methyltransferase, Ecm18. The crystal structure of Ecm18 in complex with its reaction products S-adenosyl-L-homocysteine and echinomycin was determined at 1.50 Å resolution. Phasing was achieved using a new molecular replacement package called AMPLE, which automatically derives search models from structure predictions based on ab initio protein modelling. Structural analysis indicates that a combination of proximity effects, medium effects, and catalysis by strain drives the unique transformation of the disulfide bond into the thioacetal linkage.
Effects of selenium on the structure and function of recombinant human S-adenosyl-L-methionine dependent arsenic (+3 oxidation state) methyltransferase in E. coli.

Science.gov (United States)

Geng, Zhirong; Song, Xiaoli; Xing, Zhi; Geng, Jinlong; Zhang, Sichun; Zhang, Xinrong; Wang, Zhilin

2009-05-01

The effects of Se(IV) on the structure and function of recombinant human arsenic (+3 oxidation state) methyltransferase (AS3MT) purified from the cytoplasm of Escherichia coli were studied. The coding region of human AS3MT complementary DNA was amplified from total RNA extracted from HepG2 cell by reverse transcription PCR. Soluble and active human AS3MT was expressed in the E. coli with a Trx fusion tag under a lower induction temperature of 25 degrees C. Spectra (UV-vis, circular dichroism, and fluorescence) were first used to probe the interaction of Se(IV) and recombinant human AS3MT and the structure-function relationship of the enzyme. The recombinant human AS3MT had a secondary structure of 29.0% alpha-helix, 23.9% beta-pleated sheet, 17.9% beta-turn, and 29.2% random coil. When Se(IV) was added, the content of the alpha-helix did not change, but that of the beta-pleated sheet increased remarkably in the conformation of recombinant human AS3MT. Se(IV) inhibited the enzymatic methylation of inorganic As(III) in a concentration-dependent manner. The IC(50) value for Se(IV) was 2.38 muM. Double-reciprocal (1/V vs. 1/[inorganic As(III)]) plots showed Se(IV) to be a noncompetitive inhibitor of the methylation of inorganic As(III) by recombinant human AS3MT with a K (i) value of 2.61 muM. We hypothesized that Se(IV) interacts with the sulfhydryl group of cysteine(s) in the structural residues rather than the cysteines of the active site (Cys156 and Cys206). When Se(IV) was combined with cysteine(s) in the structural residues, the conformation of recombinant human AS3MT changed and the enzymatic activity decreased. Considering the quenching of tryptophan fluorescence, Cys72 and/or Cys226 are deduced to be primary targets for Se(IV).
Levels of Key Enzymes of Methionine-Homocysteine Metabolism in Preeclampsia

Directory of Open Access Journals (Sweden)

Alejandra Pérez-Sepúlveda

2013-01-01

Full Text Available Objective. To evaluate the role of key enzymes in the methionine-homocysteine metabolism (MHM in the physiopathology of preeclampsia (PE. Methods. Plasma and placenta from pregnant women (32 controls and 16 PE patients were analyzed after informed consent. Protein was quantified by western blot. RNA was obtained with RNA purification kit and was quantified by reverse transcritase followed by real-time PCR (RT-qPCR. Identification of the C677T and A1298C methylenetetrahydrofolate reductase (MTHFR single-nucleotide polymorphisms (SNPs and A2756G methionine synthase (MTR SNP was performed using PCR followed by a high-resolution melting (HRM analysis. S-adenosyl methionine (SAM and S-adenosyl homocysteine (SAH were measured in plasma using high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS. The SNP association analysis was carried out using Fisher’s exact test. Statistical analysis was performed using a Mann-Whitney test. Results. RNA expression of MTHFR and MTR was significantly higher in patients with PE as compared with controls. Protein, SAM, and SAH levels showed no significant difference between preeclamptic patients and controls. No statistical differences between controls and PE patients were observed with the different SNPs studied. Conclusion. The RNA expression of MTHFR and MTR is elevated in placentas of PE patients, highlighting a potential compensation mechanism of the methionine-homocysteine metabolism in the physiopathology of this disease.
Mutations in the histamine N-methyltransferase gene, HNMT, are associated with nonsyndromic autosomal recessive intellectual disability

Science.gov (United States)

Heidari, Abolfazl; Tongsook, Chanakan; Najafipour, Reza; Musante, Luciana; Vasli, Nasim; Garshasbi, Masoud; Hu, Hao; Mittal, Kirti; McNaughton, Amy J. M.; Sritharan, Kumudesh; Hudson, Melissa; Stehr, Henning; Talebi, Saeid; Moradi, Mohammad; Darvish, Hossein; Arshad Rafiq, Muhammad; Mozhdehipanah, Hossein; Rashidinejad, Ali; Samiei, Shahram; Ghadami, Mohsen; Windpassinger, Christian; Gillessen-Kaesbach, Gabriele; Tzschach, Andreas; Ahmed, Iltaf; Mikhailov, Anna; Stavropoulos, D. James; Carter, Melissa T.; Keshavarz, Soraya; Ayub, Muhammad; Najmabadi, Hossein; Liu, Xudong; Ropers, Hans Hilger; Macheroux, Peter; Vincent, John B.

2015-01-01

Histamine (HA) acts as a neurotransmitter in the brain, which participates in the regulation of many biological processes including inflammation, gastric acid secretion and neuromodulation. The enzyme histamine N-methyltransferase (HNMT) inactivates HA by transferring a methyl group from S-adenosyl-l-methionine to HA, and is the only well-known pathway for termination of neurotransmission actions of HA in mammalian central nervous system. We performed autozygosity mapping followed by targeted exome sequencing and identified two homozygous HNMT alterations, p.Gly60Asp and p.Leu208Pro, in patients affected with nonsyndromic autosomal recessive intellectual disability from two unrelated consanguineous families of Turkish and Kurdish ancestry, respectively. We verified the complete absence of a functional HNMT in patients using in vitro toxicology assay. Using mutant and wild-type DNA constructs as well as in silico protein modeling, we confirmed that p.Gly60Asp disrupts the enzymatic activity of the protein, and that p.Leu208Pro results in reduced protein stability, resulting in decreased HA inactivation. Our results highlight the importance of inclusion of HNMT for genetic testing of individuals presenting with intellectual disability. PMID:26206890
Monitoring of the specific radioactivity of S-adenosylmethionine in kidney in vivo

Energy Technology Data Exchange (ETDEWEB)

Stoecker, W; Roos, G; Lange, H W; Hempel, K [Wuerzburg Univ. (Germany, F.R.). Inst. fuer Medizinische Strahlenkunde

1977-02-01

The specific radioactivity of S-adenosylmethionine was followed in the cat kidney during the infusion of L-(Me-/sup 3/H)methionine into the corresponding renal artery. For this purpose /sup 14/C-labelled 4-(2-aminoethyl)pyrocatechol((/sup 14/C)dopamine) as methyl acceptor was injected locally every 15 min and the /sup 3/H and /sup 14/C activity of the methylation product homovanillic acid, isolated from urine, was measured. Approximately 5% of the /sup 14/C label is excreted during the first renal passage as (/sup 14/C)homovanillic acid. The specific activity of S-adenosyl(Me-/sup 3/H)methionine in the kidney was calculated from the known specific radioactivity of (/sup 14/C)dopamine injected and the measured radioactivity atio, /sup 3/H : /sup 14/C, of homovanillic acid isolated from urine. The specific activity of S-adenosyn(Me-/sup 3/H)methionine reaches a constant value in kidney about 30 to 60 min after the beginning of the L-(Me-/sup 3/H)methionine infusion. This plateau value was 28% +- 14% lower than the specific activity of L-(Me-/sup 3/H)methionine in the venous blood from the corresponding kidney. The difference between the specific radioactivity of S-adenosyl(Me-/sup 3/H)-methionine in kidney and of free methionine in plasma is explained by the existence of a methionine source of minor specific activity in the kidney. The average life span of S-adenosylmethionine in the kidney is 19.5 +- 8.9 min.
Thiopurines inhibit bovine viral diarrhea virus production in a thiopurine methyltransferase-dependent manner.

Science.gov (United States)

Hoover, Spencer; Striker, Rob

2008-04-01

The family Flaviviridae comprises positive-strand RNA viral pathogens of humans and livestock with few treatment options. We have previously shown that azathioprine (AZA) has in vitro activity against bovine viral diarrhea virus (BVDV). While the mechanism of inhibition is unknown, AZA and related thiopurine nucleoside analogues have been used as immunosuppressants for decades and both AZA metabolites and cellular genes involved in AZA metabolism have been extensively characterized. Here, we show that only certain riboside metabolites have antiviral activity and identify the most potent known antiviral AZA metabolite as 6-methylmercaptopurine riboside (6MMPr). The antiviral activity of 6MMPr is antagonized by adenosine, and is specific to BVDV and not to the related yellow fever virus. An essential step in the conversion of AZA to 6MMPr is the addition of a methyl group onto the sulfur atom attached to position six of the purine ring. Intracellularly, the methyl group is added by thiopurine methyltransferase (TPMT), an S-adenosyl methionine-dependent methyltransferase. Either chemically bypassing or inhibiting TPMT modulates antiviral activity of AZA metabolites. TPMT exists in several variants with varying levels of activity and since 6MMPr is a potent antiviral, the antiviral activity of AZA may be modulated by host genetics.
S-Adenosyl-L-Methionine (SAMe): An Introduction

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... the Science For Health Care Professionals Clinical Practice Guidelines Literature Reviews All Health Information Research Research Results ... rather than an oral form (taken by mouth). Osteoarthritis The results of research on SAMe for osteoarthritis ...

A novel multifunctional O-methyltransferase implicated in a dual methylation pathway associated with lignin biosynthesis in loblolly pine.

Science.gov (United States)

Li, L; Popko, J L; Zhang, X H; Osakabe, K; Tsai, C J; Joshi, C P; Chiang, V L

1997-05-13

S-adenosyl-L-methionine (SAM)-dependent O-methyltransferases (OMTs) catalyze the methylation of hydroxycinnamic acid derivatives for the synthesis of methylated plant polyphenolics, including lignin. The distinction in the extent of methylation of lignins in angiosperms and gymnosperms, mediated by substrate-specific OMTs, represents one of the fundamental differences in lignin biosynthesis between these two classes of plants. In angiosperms, two types of structurally and functionally distinct lignin pathway OMTs, caffeic acid 3-O-methyltransferases (CAOMTs) and caffeoyl CoA 3-O-methyltransferases (CCoAOMTs), have been reported and extensively studied. However, little is known about lignin pathway OMTs in gymnosperms. We report here the first cloning of a loblolly pine (Pinus taeda) xylem cDNA encoding a multifunctional enzyme, SAM:hydroxycinnamic Acids/hydroxycinnamoyl CoA Esters OMT (AEOMT). The deduced protein sequence of AEOMT is partially similar to, but clearly distinguishable from, that of CAOMTs and does not exhibit any significant similarity with CCoAOMT protein sequences. However, functionally, yeast-expressed AEOMT enzyme catalyzed the methylation of CAOMT substrates, caffeic and 5-hydroxyferulic acids, as well as CCoAOMT substrates, caffeoyl CoA and 5-hydroxyferuloyl CoA esters, with similar specific activities and was completely inactive with substrates associated with flavonoid synthesis. The lignin-related substrates were also efficiently methylated in crude extracts of loblolly pine secondary xylem. Our results support the notion that, in the context of amino acid sequence and biochemical function, AEOMT represents a novel SAM-dependent OMT, with both CAOMT and CCoAOMT activities and thus the potential to mediate a dual methylation pathway in lignin biosynthesis in loblolly pine xylem.
A novel multifunctional O-methyltransferase implicated in a dual methylation pathway associated with lignin biosynthesis in loblolly pine

Science.gov (United States)

Li, Laigeng; Popko, Jacqueline L.; Zhang, Xing-Hai; Osakabe, Keishi; Tsai, Chung-Jui; Joshi, Chandrashekhar P.; Chiang, Vincent L.

1997-01-01

S-adenosyl-l-methionine (SAM)-dependent O-methyltransferases (OMTs) catalyze the methylation of hydroxycinnamic acid derivatives for the synthesis of methylated plant polyphenolics, including lignin. The distinction in the extent of methylation of lignins in angiosperms and gymnosperms, mediated by substrate-specific OMTs, represents one of the fundamental differences in lignin biosynthesis between these two classes of plants. In angiosperms, two types of structurally and functionally distinct lignin pathway OMTs, caffeic acid 3-O-methyltransferases (CAOMTs) and caffeoyl CoA 3-O-methyltransferases (CCoAOMTs), have been reported and extensively studied. However, little is known about lignin pathway OMTs in gymnosperms. We report here the first cloning of a loblolly pine (Pinus taeda) xylem cDNA encoding a multifunctional enzyme, SAM:hydroxycinnamic Acids/hydroxycinnamoyl CoA Esters OMT (AEOMT). The deduced protein sequence of AEOMT is partially similar to, but clearly distinguishable from, that of CAOMTs and does not exhibit any significant similarity with CCoAOMT protein sequences. However, functionally, yeast-expressed AEOMT enzyme catalyzed the methylation of CAOMT substrates, caffeic and 5-hydroxyferulic acids, as well as CCoAOMT substrates, caffeoyl CoA and 5-hydroxyferuloyl CoA esters, with similar specific activities and was completely inactive with substrates associated with flavonoid synthesis. The lignin-related substrates were also efficiently methylated in crude extracts of loblolly pine secondary xylem. Our results support the notion that, in the context of amino acid sequence and biochemical function, AEOMT represents a novel SAM-dependent OMT, with both CAOMT and CCoAOMT activities and thus the potential to mediate a dual methylation pathway in lignin biosynthesis in loblolly pine xylem. PMID:9144260
Biotechnological production of high specific activity L-35S-cysteine and L-35S-methionine by using a diploid yeast Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Gajendiran, N.; Jayachandran, N.; Unny, V.K.P.; Thyagarajan, S.; Rao, B.S.

1994-01-01

High specific activity L- 3 5 S-cysteine and L- 35 S-methionine were synthesised by using a wild type diploid strain of baker's yeast-Saccharomyces cerevisiae. Yeast cells were grown in a sulphur depleted synthetic medium in which Na 2 3 5 SO 4 (50 mCi/ml) was supplemented as the sole sulphur source. The level of incorporation was 60% on an average. The protein hydrolysate of the cultured cells was subjected to paper and column chromatographic separations to get the individual L- 3 5 S-aminoacids. The radiochemical yields of cysteine and methionine were 6-7% and 18-20% respectively. The radiochemical purity of the products was >95%. The highest specific activity for the products obtained by employing this method was 1100 Ci/mmole from the starting material, Na 2 35 SO 4 , with a specific activity of 1350 Ci/mmole. (Author)
A kinetic and mechanistic study on the oxidation of l-methionine and N-acetyl l-methionine by cerium(IV) in sulfuric acid medium

OpenAIRE

T. Sumathi; P. Shanmugasundaram; G. Chandramohan

2016-01-01

The kinetics of oxidation of l-methionine and N-acetyl l-methionine by Ce(IV) in sulfuric acid–sulfate media in the range of 288.1–298.1 K has been investigated. The major oxidation products of methionine and N-acetyl l-methionine have been identified as methionine sulfoxide and N-acetyl methionine sulfoxide. The major oxidation products have been confirmed by qualitative analysis and boiling point. The reaction was first order with respect to l-methionine, N-acetyl l-methionine and Ce(IV). I...
Differential metabolism of L-phenylalanine in the formation of aromatic volatiles in melon (Cucumis melo L.) fruit.

Science.gov (United States)

Gonda, Itay; Davidovich-Rikanati, Rachel; Bar, Einat; Lev, Shery; Jhirad, Pliaa; Meshulam, Yuval; Wissotsky, Guy; Portnoy, Vitaly; Burger, Joseph; Schaffer, Arthur A; Tadmor, Yaakov; Giovannoni, James J; Fei, Zhangjun; Fait, Aaron; Katzir, Nurit; Lewinsohn, Efraim

2018-04-01

Studies on the active pathways and the genes involved in the biosynthesis of L-phenylalanine-derived volatiles in fleshy fruits are sparse. Melon fruit rinds converted stable-isotope labeled L-phe into more than 20 volatiles. Phenylpropanes, phenylpropenes and benzenoids are apparently produced via the well-known phenylpropanoid pathway involving phenylalanine ammonia lyase (PAL) and being (E)-cinnamic acid a key intermediate. Phenethyl derivatives seemed to be derived from L-phe via a separate biosynthetic route not involving (E)-cinnamic acid and PAL. To explore for a biosynthetic route to (E)-cinnamaldehyde in melon rinds, soluble protein cell-free extracts were assayed with (E)-cinnamic acid, CoA, ATP, NADPH and MgSO 4 , producing (E)-cinnamaldehyde in vitro. In this context, we characterized CmCNL, a gene encoding for (E)-cinnamic acid:coenzyme A ligase, inferred to be involved in the biosynthesis of (E)-cinnamaldehyde. Additionally we describe CmBAMT, a SABATH gene family member encoding a benzoic acid:S-adenosyl-L-methionine carboxyl methyltransferase having a role in the accumulation of methyl benzoate. Our approach leads to a more comprehensive understanding of L-phe metabolism into aromatic volatiles in melon fruit. Copyright © 2018 Elsevier Ltd. All rights reserved.
Determination of the Structure and Catalytic Mechanism of Sorghum bicolor Caffeic Acid O-Methyltransferase and the Structural Impact of Three brown midrib12 Mutations.

Science.gov (United States)

Green, Abigail R; Lewis, Kevin M; Barr, John T; Jones, Jeffrey P; Lu, Fachuang; Ralph, John; Vermerris, Wilfred; Sattler, Scott E; Kang, ChulHee

2014-08-01

Using S-adenosyl-methionine as the methyl donor, caffeic acid O-methyltransferase from sorghum (Sorghum bicolor; SbCOMT) methylates the 5-hydroxyl group of its preferred substrate, 5-hydroxyconiferaldehyde. In order to determine the mechanism of SbCOMT and understand the observed reduction in the lignin syringyl-to-guaiacyl ratio of three brown midrib12 mutants that carry COMT gene missense mutations, we determined the apo-form and S-adenosyl-methionine binary complex SbCOMT crystal structures and established the ternary complex structure with 5-hydroxyconiferaldehyde by molecular modeling. These structures revealed many features shared with monocot ryegrass (Lolium perenne) and dicot alfalfa (Medicago sativa) COMTs. SbCOMT steady-state kinetic and calorimetric data suggest a random bi-bi mechanism. Based on our structural, kinetic, and thermodynamic results, we propose that the observed reactivity hierarchy among 4,5-dihydroxy-3-methoxycinnamyl (and 3,4-dihydroxycinnamyl) aldehyde, alcohol, and acid substrates arises from the ability of the aldehyde to stabilize the anionic intermediate that results from deprotonation of the 5-hydroxyl group by histidine-267. Additionally, despite the presence of other phenylpropanoid substrates in vivo, sinapaldehyde is the preferential product, as demonstrated by its low K m for 5-hydroxyconiferaldehyde. Unlike its acid and alcohol substrates, the aldehydes exhibit product inhibition, and we propose that this is due to nonproductive binding of the S-cis-form of the aldehydes inhibiting productive binding of the S-trans-form. The S-cis-aldehydes most likely act only as inhibitors, because the high rotational energy barrier around the 2-propenyl bond prevents S-trans-conversion, unlike alcohol substrates, whose low 2-propenyl bond rotational energy barrier enables rapid S-cis/S-trans-interconversion. © 2014 American Society of Plant Biologists. All Rights Reserved.
Characterization of a Vitis vinifera cv. Cabernet Sauvignon 3',5'-O-methyltransferase showing strong preference for anthocyanins and glycosylated flavonols.

Science.gov (United States)

Lücker, Joost; Martens, Stefan; Lund, Steven T

2010-09-01

At ripening initiation in red grapevine (Vitis vinifera) berries, the exocarp turns color from green to red and then to purple due to the accumulation and extent of methylation of anthocyanins. The accumulation of transcripts encoding an O-methyltransferase was recently shown to be closely correlated with the onset of ripening and the degree of blue/purple pigmentation in grapevine berries; however, the biochemical function of this gene has remained uncharacterized. In this study, an O-methyltransferase cDNA that showed a distinct expression pattern when compared to closely related sequences was expressed in Escherichia coli and enzyme assays were carried out with a broad array of anthocyanin and other flavonoid substrates. We demonstrate that this enzyme carries out 3',5'-O-methylation of anthocyanins and flavonol compounds in vitro, which are known to be present in grape berries, with a preference for glycosylated substrates. The highest relative specific activity for the enzyme was found with delphinidin 3-O-glucoside as substrate. The enzyme is not able to methylate flavan type skeletons with chiral centers, such as either catechins or dihydroquercetin. The enzyme showed negligible specific activity for caffeoyl-CoA, compared to flavonol and anthocyanin substrates. Phylogenetic analysis of the O-methyltransferase suggests that it may be a member of a distinct subclass of Type 2 bivalent metal-dependent S-adenosyl-methionine O-methyltransferases. (c) 2010. Published by Elsevier Ltd. All rights reserved.
Heating Changes Bio-Schwertmannite Microstructure and Arsenic(III Removal Efficiency

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Xingxing Qiao

2017-01-01

Full Text Available Schwertmannite (Sch is an efficient adsorbent for arsenic(III removal from arsenic(III-contaminated groundwater. In this study, bio-schertmannite was synthesized in the presence of dissolved ferrous ions and Acidithiobacillus ferrooxidans LX5 in a culture media. Bio-synthesized Sch characteristics, such as total organic carbon (TOC, morphology, chemical functional groups, mineral phase, specific surface area, and pore volume were systematically studied after it was dried at 105 °C and then heated at 250–550 °C. Differences in arsenic(III removal efficiency between 105 °C dried-sch and 250–550 °C heated-sch also were investigated. The results showed that total organic carbon content in Sch and Sch weight gradually decreased when temperature increased from 105 °C to 350 °C. Sch partly transformed to another nanocrystalline or amorphous phase above 350 °C. The specific surface area of 250 °C heated-sch was 110.06 m2/g compared to 5.14 m2/g for the 105 °C dried-sch. Total pore volume of 105 °C dried-sch was 0.025 cm3/g with 32.0% mesopore and 68.0% macropore. However, total pore volume of 250 °C heated-mineral was 0.106 cm3/g with 23.6% micropore, 33.0% mesopore, and 43.4% macropore. The arsenic(III removal efficiency from an initial 1 mg/L arsenic(III solution (pH 7.5 was 25.1% when 0.25 g/L of 105 °C dried-sch was used as adsorbent. However, this efficiency increased to 93.0% when using 250 °C heated-sch as adsorbent. Finally, the highest efficiency for arsenic(III removal was obtained with sch-250 °C due to high amounts of sorption sites in agreement with the high specific surface area (SSA obtained for this sample.
Mutations in the histamine N-methyltransferase gene, HNMT, are associated with nonsyndromic autosomal recessive intellectual disability.

Science.gov (United States)

Heidari, Abolfazl; Tongsook, Chanakan; Najafipour, Reza; Musante, Luciana; Vasli, Nasim; Garshasbi, Masoud; Hu, Hao; Mittal, Kirti; McNaughton, Amy J M; Sritharan, Kumudesh; Hudson, Melissa; Stehr, Henning; Talebi, Saeid; Moradi, Mohammad; Darvish, Hossein; Arshad Rafiq, Muhammad; Mozhdehipanah, Hossein; Rashidinejad, Ali; Samiei, Shahram; Ghadami, Mohsen; Windpassinger, Christian; Gillessen-Kaesbach, Gabriele; Tzschach, Andreas; Ahmed, Iltaf; Mikhailov, Anna; Stavropoulos, D James; Carter, Melissa T; Keshavarz, Soraya; Ayub, Muhammad; Najmabadi, Hossein; Liu, Xudong; Ropers, Hans Hilger; Macheroux, Peter; Vincent, John B

2015-10-15

Histamine (HA) acts as a neurotransmitter in the brain, which participates in the regulation of many biological processes including inflammation, gastric acid secretion and neuromodulation. The enzyme histamine N-methyltransferase (HNMT) inactivates HA by transferring a methyl group from S-adenosyl-l-methionine to HA, and is the only well-known pathway for termination of neurotransmission actions of HA in mammalian central nervous system. We performed autozygosity mapping followed by targeted exome sequencing and identified two homozygous HNMT alterations, p.Gly60Asp and p.Leu208Pro, in patients affected with nonsyndromic autosomal recessive intellectual disability from two unrelated consanguineous families of Turkish and Kurdish ancestry, respectively. We verified the complete absence of a functional HNMT in patients using in vitro toxicology assay. Using mutant and wild-type DNA constructs as well as in silico protein modeling, we confirmed that p.Gly60Asp disrupts the enzymatic activity of the protein, and that p.Leu208Pro results in reduced protein stability, resulting in decreased HA inactivation. Our results highlight the importance of inclusion of HNMT for genetic testing of individuals presenting with intellectual disability. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
2′-O Methylation of Internal Adenosine by Flavivirus NS5 Methyltransferase

Science.gov (United States)

Dong, Hongping; Chang, David C.; Hua, Maggie Ho Chia; Lim, Siew Pheng; Chionh, Yok Hian; Hia, Fabian; Lee, Yie Hou; Kukkaro, Petra; Lok, Shee-Mei; Dedon, Peter C.; Shi, Pei-Yong

2012-01-01

RNA modification plays an important role in modulating host-pathogen interaction. Flavivirus NS5 protein encodes N-7 and 2′-O methyltransferase activities that are required for the formation of 5′ type I cap (m7GpppAm) of viral RNA genome. Here we reported, for the first time, that flavivirus NS5 has a novel internal RNA methylation activity. Recombinant NS5 proteins of West Nile virus and Dengue virus (serotype 4; DENV-4) specifically methylates polyA, but not polyG, polyC, or polyU, indicating that the methylation occurs at adenosine residue. RNAs with internal adenosines substituted with 2′-O-methyladenosines are not active substrates for internal methylation, whereas RNAs with adenosines substituted with N6-methyladenosines can be efficiently methylated, suggesting that the internal methylation occurs at the 2′-OH position of adenosine. Mass spectroscopic analysis further demonstrated that the internal methylation product is 2′-O-methyladenosine. Importantly, genomic RNA purified from DENV virion contains 2′-O-methyladenosine. The 2′-O methylation of internal adenosine does not require specific RNA sequence since recombinant methyltransferase of DENV-4 can efficiently methylate RNAs spanning different regions of viral genome, host ribosomal RNAs, and polyA. Structure-based mutagenesis results indicate that K61-D146-K181-E217 tetrad of DENV-4 methyltransferase forms the active site of internal methylation activity; in addition, distinct residues within the methyl donor (S-adenosyl-L-methionine) pocket, GTP pocket, and RNA-binding site are critical for the internal methylation activity. Functional analysis using flavivirus replicon and genome-length RNAs showed that internal methylation attenuated viral RNA translation and replication. Polymerase assay revealed that internal 2′-O-methyladenosine reduces the efficiency of RNA elongation. Collectively, our results demonstrate that flavivirus NS5 performs 2′-O methylation of internal adenosine of
Determination of the Structure and Catalytic Mechanism of Sorghum bicolor Caffeic Acid O-Methyltransferase and the Structural Impact of Three brown midrib12 Mutations1[W

Science.gov (United States)

Green, Abigail R.; Lewis, Kevin M.; Barr, John T.; Jones, Jeffrey P.; Lu, Fachuang; Ralph, John; Vermerris, Wilfred; Sattler, Scott E.; Kang, ChulHee

2014-01-01

Using S-adenosyl-methionine as the methyl donor, caffeic acid O-methyltransferase from sorghum (Sorghum bicolor; SbCOMT) methylates the 5-hydroxyl group of its preferred substrate, 5-hydroxyconiferaldehyde. In order to determine the mechanism of SbCOMT and understand the observed reduction in the lignin syringyl-to-guaiacyl ratio of three brown midrib12 mutants that carry COMT gene missense mutations, we determined the apo-form and S-adenosyl-methionine binary complex SbCOMT crystal structures and established the ternary complex structure with 5-hydroxyconiferaldehyde by molecular modeling. These structures revealed many features shared with monocot ryegrass (Lolium perenne) and dicot alfalfa (Medicago sativa) COMTs. SbCOMT steady-state kinetic and calorimetric data suggest a random bi-bi mechanism. Based on our structural, kinetic, and thermodynamic results, we propose that the observed reactivity hierarchy among 4,5-dihydroxy-3-methoxycinnamyl (and 3,4-dihydroxycinnamyl) aldehyde, alcohol, and acid substrates arises from the ability of the aldehyde to stabilize the anionic intermediate that results from deprotonation of the 5-hydroxyl group by histidine-267. Additionally, despite the presence of other phenylpropanoid substrates in vivo, sinapaldehyde is the preferential product, as demonstrated by its low Km for 5-hydroxyconiferaldehyde. Unlike its acid and alcohol substrates, the aldehydes exhibit product inhibition, and we propose that this is due to nonproductive binding of the S-cis-form of the aldehydes inhibiting productive binding of the S-trans-form. The S-cis-aldehydes most likely act only as inhibitors, because the high rotational energy barrier around the 2-propenyl bond prevents S-trans-conversion, unlike alcohol substrates, whose low 2-propenyl bond rotational energy barrier enables rapid S-cis/S-trans-interconversion. PMID:24948836
Novel double-isotope technique for enzymatic assay of catecholamines, permitting high precision, sensitivity and plasma sample capacity

International Nuclear Information System (INIS)

Brown, M.J.; Jenner, D.A.

1981-01-01

A novel use of a double-isotope method is described which allows radioenzymatic assays to combine precision and sensitivity. In the catechol O-methyltransferase assay separate portions of each plasma sample are incubated with either S-[ 3 H]- or S-[ 14 C]-adenosyl-L-methionine. Standards of noradrenaline and adrenaline are added to the latter portions and are thus converted into standards of [ 14 C]metadrenalines. These are added to the 3 H-labelled portions after the incubation, where they function as tracers. The final recovery of 14 C radioactivity corrects for (a) the efficiency of methylation in the plasma sample concerned and (b) the recovery of metadrenalines during the extraction procedures. The 3 H/ 14 C ratio is constant in each assay for a given catecholamine concentration and is determined for samples to which standards of noradrenaline and adrenaline are added to the 3 H- (as well as the 14 C-) labelled portions before the initial incubation. The sensitivity of the assay is increased by using high specific radioactivity S-[ 3 H]adenosyl-L-methionine, and low backgrounds are maintained by catecholamine depletion in vivo in the rats used for enzyme preparation. Both catecholamines (1.5 pg/ml; 10 pmol/l) may be detected; the coefficients of variation are 3.0 and 3.2% for noradrenaline and adrenaline respectively (intra-assay) and 4.6 and 5.0% (inter-assay). (author)
Inhibition of thiopurine S-methyltransferase activity by impurities in commercially available substrates: a factor for differing results of TPMT measurements.

Science.gov (United States)

Kröplin, T; Fischer, C; Iven, H

1999-06-01

Thiopurine S-methyltransferase (TPMT) activity, when measured in red blood cells (RBC) with a recently published TPMT activity assay using 6-thioguanine (6-TG) as substrate, could not be reproduced in another laboratory. We investigated factors which could influence the results of the TPMT activity measurement. We tested twelve 6-TG and four 6-mercaptopurine (6-MP) compounds from different suppliers as substrates and determined the enzyme kinetic parameters Km and Vmax. Furthermore, we studied the influence of different 6-TG compounds on the affinity of the methyl donor S-adenosyl-L-methionine (SAM) to the TPMT enzyme. All 6-TG products were of equal purity (declared >98% by the supplier): this was ascertained by HPLC. However, the rate of methylation obtained following incubation with 6-TG from different suppliers ranged from 10% to 100% when incubated with the same RBC lysate. The lowest apparent Km value for a 6-TG was 22.3 micromol x l(-1), while the product with the highest methylation rate showed a Km of 156 micromol x l(-1). From these results we assume that there is a contaminant in some 6-TG products, which acts as a strong inhibitor of TPMT activity. Compounds possibly used for the synthesis of 6-TG (guanine, pyridine, 6-chloroguanine) did not affect the methylation rate. Thioxanthine, which is known to be a strong inhibitor of TPMT when added to the assay system to give a 2% contamination, reduced TPMT activity from 100% to 72%. Using 6-MP from different suppliers as substrate resulted in Km values ranging from 110 to 162 micromol x l(-1) and Vmox values ranging from 54 to 68 nmol 6-MMP x g(-1)Hb x h(-1). The Km value for the methyl donor SAM was similar to and independent from the thiopurine substrates tested (range 4.9-11 micromol-l(-1) SAM). In contrast to other investigators, we found non-enzymatic S-methylation, which was negligible under our assay conditions (3% with 128 micromol x l(-1) SAM), but could become relevant in experiments using higher
Structural basis for recognition of S-adenosylhomocysteine by riboswitches

Energy Technology Data Exchange (ETDEWEB)

Edwards, A.L.; Heroux, A.; Reyes, F. E.; Batey, R. T.

2010-11-01

S-adenosyl-(L)-homocysteine (SAH) riboswitches are regulatory elements found in bacterial mRNAs that up-regulate genes involved in the S-adenosyl-(L)-methionine (SAM) regeneration cycle. To understand the structural basis of SAH-dependent regulation by RNA, we have solved the structure of its metabolite-binding domain in complex with SAH. This structure reveals an unusual pseudoknot topology that creates a shallow groove on the surface of the RNA that binds SAH primarily through interactions with the adenine ring and methionine main chain atoms and discriminates against SAM through a steric mechanism. Chemical probing and calorimetric analysis indicate that the unliganded RNA can access bound-like conformations that are significantly stabilized by SAH to direct folding of the downstream regulatory switch. Strikingly, we find that metabolites bearing an adenine ring, including ATP, bind this aptamer with sufficiently high affinity such that normal intracellular concentrations of these compounds may influence regulation of the riboswitch.
Structural Basis for Recognition of S-adenosylhomocysteine by Riboswitches

Energy Technology Data Exchange (ETDEWEB)

A Edwards; F Reyes; A Heroux; R Batey

2011-12-31

S-adenosyl-(L)-homocysteine (SAH) riboswitches are regulatory elements found in bacterial mRNAs that up-regulate genes involved in the S-adenosyl-(L)-methionine (SAM) regeneration cycle. To understand the structural basis of SAH-dependent regulation by RNA, we have solved the structure of its metabolite-binding domain in complex with SAH. This structure reveals an unusual pseudoknot topology that creates a shallow groove on the surface of the RNA that binds SAH primarily through interactions with the adenine ring and methionine main chain atoms and discriminates against SAM through a steric mechanism. Chemical probing and calorimetric analysis indicate that the unliganded RNA can access bound-like conformations that are significantly stabilized by SAH to direct folding of the downstream regulatory switch. Strikingly, we find that metabolites bearing an adenine ring, including ATP, bind this aptamer with sufficiently high affinity such that normal intracellular concentrations of these compounds may influence regulation of the riboswitch.
Transfer RNA methylases in rat placenta

International Nuclear Information System (INIS)

Jagtiani, S.K.; Narurkar, L.M.; Narurkar, M.V.

1977-01-01

Presence of tRNA methylases (5-adenosylmethionine : tRNA methyltransferases) was demonstrated at various stages of gestation in rat placenta, the enzyme being 50-100% higher than that of adult rat liver during early gestation. Placental tRNA methylases were shown to differ from those of liver in the extent of methylation. Glycine methyltransferase (S-adenosylmethionine : glycine methyltransferase), a regulatory enzyme in adult rat liver, was absent in placenta throughout gestation. The placental tRNA methylases could be inhibited in vitro by semipurified glycine methyltransferase from adult rat liver. The high placental tRNA methylase activity was comparable with the inhibitor-free enzyme activity of the adult rat liver. S-adenosyl-[Me- 14 C]-methionine was used in the investigation. (author)
A simple method for enzymatic synthesis of unlabeled and radiolabeled Hydroxycinnamate-CoA

Energy Technology Data Exchange (ETDEWEB)

Rautergarten, Carsten; Baidoo, Edward; Keasling, Jay; Vibe Scheller, Henrik

2011-07-20

Hydroxycinnamate coenzyme A (CoA) thioesters are substrates for biosynthesis of lignin and hydroxycinna- mate esters of polysaccharides and other polymers. Hence, a supply of these substrates is essential for investigation of cell wall biosynthesis. In this study, three recombinant enzymes, caffeic acid 3-O-methyltransferase, 4-coumarate- CoA ligase 1, and 4-coumarate-CoA ligase 5, were cloned from wheat, tobacco, and Arabidopsis, respectively, and were used to synthesize {sup 14}C-feruloyl-CoA, caffeoyl-CoA, p-coumaroyl-CoA, feruloyl-CoA, and sinapoyl-CoA. The corresponding hydroxycinnamoyl-CoA thioesters were high-performance liquid chromatography purified, the only extraction/purification step necessary, with total yields between 88-95%. Radiolabeled {sup 14}C-feruloyl-CoA was generated from caffeic acid and S-adenosyl-{sup 14}C-methionine under the combined action of caffeic acid 3-O-methyltransferase and 4-coumarate-CoA ligase 1. About 70% of {sup 14}C-methyl groups from S-adenosyl methionine were incorporated into the final product. The methods presented are simple, fast, and efficient for the preparation of the hydroxycinnamate thioesters.
Molecular Cloning and Characterization of O-Methyltransferase from Mango Fruit (Mangifera indica cv. Alphonso).

Science.gov (United States)

Chidley, Hemangi G; Oak, Pranjali S; Deshpande, Ashish B; Pujari, Keshav H; Giri, Ashok P; Gupta, Vidya S

2016-05-01

Flavour of ripe Alphonso mango is invariably dominated by the de novo appearance of lactones and furanones during ripening. Of these, furanones comprising furaneol (4-hydroxy-2,5-dimethyl-3(2H)-furanone) and mesifuran (2,5-dimethyl-4-methoxy-3(2H)-furanone) are of particular importance due to their sweet, fruity caramel-like flavour characters and low odour detection thresholds. We isolated a 1056 bp complete open reading frame of a cDNA encoding S-adenosyl-L-methionine-dependent O-methyltransferase from Alphonso mango. The recombinantly expressed enzyme, MiOMTS showed substrate specificity towards furaneol and protocatechuic aldehyde synthesizing mesifuran and vanillin, respectively, in an in vitro assay reaction. A semi-quantitative PCR analysis showed fruit-specific expression of MiOMTS transcripts. Quantitative real-time PCR displayed ripening-related expression pattern of MiOMTS in both pulp and skin of Alphonso mango. Also, early and significantly enhanced accumulation of its transcripts was detected in pulp and skin of ethylene-treated fruits. Ripening-related and fruit-specific expression profile of MiOMTS and substrate specificity towards furaneol is a suggestive of its involvement in the synthesis of mesifuran in Alphonso mango. Moreover, a significant trigger in the expression of MiOMTS transcripts in ethylene-treated fruits point towards the transcriptional regulation of mesifuran biosynthesis by ethylene.
A kinetic and mechanistic study on the oxidation of l-methionine and N-acetyl l-methionine by cerium(IV in sulfuric acid medium

Directory of Open Access Journals (Sweden)

T. Sumathi

2016-09-01

Full Text Available The kinetics of oxidation of l-methionine and N-acetyl l-methionine by Ce(IV in sulfuric acid–sulfate media in the range of 288.1–298.1 K has been investigated. The major oxidation products of methionine and N-acetyl l-methionine have been identified as methionine sulfoxide and N-acetyl methionine sulfoxide. The major oxidation products have been confirmed by qualitative analysis and boiling point. The reaction was first order with respect to l-methionine, N-acetyl l-methionine and Ce(IV. Increase in [H+], ionic strength and HSO4- did not affect the reaction rate. Under the experimental conditions, Ce4+ was the effective oxidizing species of cerium. Increase in dielectric constant of the medium decreased the reaction rate. Under nitrogen atmosphere, the reaction system can initiate polymerization of acrylonitrile, indicating the generation of free radicals. Activation parameters associated with the overall reaction have been calculated.
Biosynthetic preparation of 35-S labelled methionine

International Nuclear Information System (INIS)

Freud, A.; Hirshfeld, N.; Teitelbaum, Z.; Heimer, Y.

1986-11-01

High specific activity methionine with sulfur-35 was prepared in our laboratory by growing Baker's yeast cells, in a medium containing 35 S-sulfate. L-S 35 methionine was prepared from the acid hydrolyzate of the proteins by chromatography on whatman paper. The specific activity was determined using o-phtaladehyde as a fluorophore to form a fluorescent complex. The specific activity was found to be usually greater than 800 Ci/mmol. (Author)

Gender differences in methionine accumulation and metabolism in freshly isolated mouse hepatocytes: Potential roles in toxicity

International Nuclear Information System (INIS)

Dever, Joseph T.; Elfarra, Adnan A.

2009-01-01

L-Methionine (Met) is hepatotoxic at high concentrations. Because Met toxicity in freshly isolated mouse hepatocytes is gender-dependent, the goal of this study was to assess the roles of Met accumulation and metabolism in the increased sensitivity of male hepatocytes to Met toxicity compared with female hepatocytes. Male hepatocytes incubated with Met (30 mM) at 37 o C exhibited higher levels of intracellular Met at 0.5, 1.0, and 1.5 h, respectively, compared to female hepatocytes. Conversely, female hepatocytes had higher levels of S-adenosyl-L-methionine compared to male hepatocytes. Female hepatocytes also exhibited higher L-methionine-L-sulfoxide levels relative to control hepatocytes, whereas the increases in L-methionine-D-sulfoxide (Met-D-O) levels were similar in hepatocytes of both genders. Addition of aminooxyacetic acid (AOAA), an inhibitor of Met transamination, significantly increased Met levels at 1.5 h and increased Met-D-O levels at 1.0 and 1.5 h only in Met-exposed male hepatocytes. No gender differences in cytosolic Met transamination activity by glutamine transaminase K were detected. However, female mouse liver cytosol exhibited higher methionine-DL-sulfoxide (MetO) reductase activity than male mouse liver cytosol at low (0.25 and 0.5 mM) MetO concentrations. Collectively, these results suggest that increased cellular Met accumulation, decreased Met transmethylation, and increased Met and MetO transamination in male mouse hepatocytes may be contributing to the higher sensitivity of the male mouse hepatocytes to Met toxicity in comparison with female mouse hepatocytes.
Methionine metabolism in apple tissue: implications of S-adenosylmethionine as an intermediate in the conversion of methionine to ethylene

International Nuclear Information System (INIS)

Adams, D.O.; Yang, S.F.

1977-01-01

If S-adenosylmethionine (SAM) is the direct precursor of ethylene as previously proposed, it is expected that 5'-S-methyl-5'-thioadenosine (MTA) would be the fragment nucleoside. When [Me- 14 C] or ( 35 S)methionine was fed to climacteric apple (Malus sylvestris Mill) tissue, radioactive 5-S-methyl-5-thioribose (MTR) was identified as the predominant product and MTA as a minor one. When the conversion of methionine into ethylene was inhibited by L-2-amino-4-(2'-amino-ethoxy)-trans-3-butenoic acid, the conversion of ( 35 S) or (Me- 14 C)methionine into MTR was similarly inhibited. Furthermore, the formation of MTA and MTR from ( 35 S)methionine was observed only in climacteric tissue which produced ethylene and actively converted methionine to ethylene but not in preclimacteric tissue which did not produce ethylene or convert methionine to ethylene. These observations suggest that the conversion of methionine into MTA and MTR is closely related to ethylene biosynthesis and provide indirect evidence that SAM may be an intermediate in the conversion of methionine to ethylene. When ( 35 S)MTA was fed to climacteric or preclimacteric apple tissue, radioactivity was efficiently incorporated into MTR and methionine. However, when ( 35 S)MTR was administered, radioactivity was efficiently incorporated into methionine but not MTA. A scheme is presented for the production of ethylene from methionine
Crystal structure of a new homochiral one-dimensional zincophosphate containing l-methionine

Directory of Open Access Journals (Sweden)

Nadjet Chouat

2015-07-01

Full Text Available catena-Poly[[(l-methionine-κOzinc]-μ3-(hydrogen phosphato-κ3O:O′:O′′], [Zn{PO3(OH}(C5H11NO2S]n, a new one-dimensional homochiral zincophosphate, was hydrothermally synthesized using l-methionine as a structure-directing agent. The compound consists of a network of ZnO4 and (HOPO3 tetrahedra that form ladder-like chains of edge-fused Zn2P2O4 rings propagating parallel to [100]. The chains are decorated on each side by zwitterionic l-methionine ligands, which interact with the inorganic framework via Zn—O coordination bonds. The structure displays interchain N—H...O and O—H...S hydrogen bonds.
Utilization of 35S methionine by the goat

International Nuclear Information System (INIS)

Champredon, C.; Pion, R.

1977-01-01

A mixture of 2.5 g of D,L-methionine and 2.1 mCi of L- 35 S methionine is injected into the rumen of two young dry goats. Abomasal contents and blood are sampled for 4 days after intraruminal injection of the tracer. Total radioactivity and specific activity of sulfur amino acids are measured in free- and protein-bound fractions of abomasal contents and blood. The radioactivity of the abomasal content soluble fraction (TCA) increases very rapidly. The main labelled compound in the TCA extract during the first hour is methionine. Total plasma radioactivity increases during the 9 hours following the injection, then decreases slowly. It is mainly found in the extract during the first hours of the experiment, but is almost totally recovered in the protein-bound fraction 48 hours after the injection. It is concluded that a part of the 35 S is absorbed directly from the rumen as unidentified sulfur-labelled compounds and is carried by the bloodstream, but a significant proportion of the 35 S introduced into the rumen as methionine is incorporated into microbial protein or enters the intestine directly [fr
Mutagenic and Cytotoxic Properties of 6-Thioguanine, S6-Methylthioguanine, and Guanine-S6-sulfonic Acid*S⃞

OpenAIRE

Yuan, Bifeng; Wang, Yinsheng

2008-01-01

Thiopurine drugs, including 6-thioguanine (SG), 6-mercaptopurine, and azathioprine, are widely employed anticancer agents and immunosuppressants. The formation of SG nucleotides from the thiopurine prodrugs and their subsequent incorporation into nucleic acids are important for the drugs to exert their cytotoxic effects. SG in DNA can be methylated by S-adenosyl-l-methionine to give S6-methylthioguanine (S6mG) and oxidized by UVA light to render guanine-S6-sulfonic acid ...
Deregulation of S-adenosylmethionine biosynthesis and regeneration improves methylation in the E. coli de novo vanillin biosynthesis pathway.

Science.gov (United States)

Kunjapur, Aditya M; Hyun, Jason C; Prather, Kristala L J

2016-04-11

Vanillin is an industrially valuable molecule that can be produced from simple carbon sources in engineered microorganisms such as Saccharomyces cerevisiae and Escherichia coli. In E. coli, de novo production of vanillin was demonstrated previously as a proof of concept. In this study, a series of data-driven experiments were performed in order to better understand limitations associated with biosynthesis of vanillate, which is the immediate precursor to vanillin. Time-course experiments monitoring production of heterologous metabolites in the E. coli de novo vanillin pathway revealed a bottleneck in conversion of protocatechuate to vanillate. Perturbations in central metabolism intended to increase flux into the heterologous pathway increased average vanillate titers from 132 to 205 mg/L, but protocatechuate remained the dominant heterologous product on a molar basis. SDS-PAGE, in vitro activity measurements, and L-methionine supplementation experiments suggested that the decline in conversion rate was influenced more by limited availability of the co-substrate S-adenosyl-L-methionine (AdoMet or SAM) than by loss of activity of the heterologous O-methyltransferase. The combination of metJ deletion and overexpression of feedback-resistant variants of metA and cysE, which encode enzymes involved in SAM biosynthesis, increased average de novo vanillate titers by an additional 33% (from 205 to 272 mg/L). An orthogonal strategy intended to improve SAM regeneration through overexpression of native mtn and luxS genes resulted in a 25% increase in average de novo vanillate titers (from 205 to 256 mg/L). Vanillate production improved further upon supplementation with methionine (as high as 419 ± 58 mg/L), suggesting potential for additional enhancement by increasing SAM availability. Results from this study demonstrate context dependency of engineered pathways and highlight the limited methylation capacity of E. coli. Unlike in previous efforts to improve SAM or
In Vitro Optimization of Enzymes Involved in Precorrin-2 Synthesis Using Response Surface Methodology.

Science.gov (United States)

Fang, Huan; Dong, Huina; Cai, Tao; Zheng, Ping; Li, Haixing; Zhang, Dawei; Sun, Jibin

2016-01-01

In order to maximize the production of biologically-derived chemicals, kinetic analyses are first necessary for predicting the role of enzyme components and coordinating enzymes in the same reaction system. Precorrin-2 is a key precursor of cobalamin and siroheme synthesis. In this study, we sought to optimize the concentrations of several molecules involved in precorrin-2 synthesis in vitro: porphobilinogen synthase (PBGS), porphobilinogen deaminase (PBGD), uroporphyrinogen III synthase (UROS), and S-adenosyl-l-methionine-dependent urogen III methyltransferase (SUMT). Response surface methodology was applied to develop a kinetic model designed to maximize precorrin-2 productivity. The optimal molar ratios of PBGS, PBGD, UROS, and SUMT were found to be approximately 1:7:7:34, respectively. Maximum precorrin-2 production was achieved at 0.1966 ± 0.0028 μM/min, agreeing with the kinetic model's predicted value of 0.1950 μM/min. The optimal concentrations of the cofactor S-adenosyl-L-methionine (SAM) and substrate 5-aminolevulinic acid (ALA) were also determined to be 200 μM and 5 mM, respectively, in a tandem-enzyme assay. By optimizing the relative concentrations of these enzymes, we were able to minimize the effects of substrate inhibition and feedback inhibition by S-adenosylhomocysteine on SUMT and thereby increase the production of precorrin-2 by approximately five-fold. These results demonstrate the effectiveness of kinetic modeling via response surface methodology for maximizing the production of biologically-derived chemicals.
A new metabolic pathway of arsenite: arsenic-glutathione complexes are substrates for human arsenic methyltransferase Cyt19

Energy Technology Data Exchange (ETDEWEB)

Hayakawa, Toru [National Institute for Environmental Studies, Environmental Health Sciences Division, Ibaraki (Japan); Chiba University, Faculty of Pharmaceutical Sciences, Chiba (Japan); Kobayashi, Yayoi; Cui, Xing; Hirano, Seishiro [National Institute for Environmental Studies, Environmental Health Sciences Division, Ibaraki (Japan)

2005-04-01

The metabolism of arsenic is generally accepted to proceed by repetitive reduction and oxidative methylation; the latter is mediated by arsenic methyltransferase (Cyt19). In human urine, the major metabolites of inorganic arsenicals such as arsenite (iAs{sup III}) and arsenate (iAs{sup V}) are monomethylarsonic acid (MMA{sup V}) and dimethylarsinic acid (DMA{sup V}). On the other hand, in rat bile, the major metabolites of iAs{sup III} have been reported to be arsenic-glutathione (As-GSH) complexes. In the present study we investigate whether these As-GSH complexes are substrates for arsenic methyltransferase by using human recombinant Cyt19. Analyses by high-performance liquid chromatography-inductively coupled plasma mass spectrometry suggested that arsenic triglutathione (ATG) was generated nonenzymatically from iAs{sup III} when GSH was present at concentrations 2 mM or higher. Human recombinant Cyt19 catalyzed transfer of a methyl group from S-adenosyl-l-methionine to arsenic and produced monomethyl and dimethyl arsenicals. The methylation of arsenic was catalyzed by Cyt19 only when ATG was present in the reaction mixture. Moreover, monomethylarsonic diglutathione (MADG) was a substrate of Cyt19 for further methylation to dimethylarsinic glutathione (DMAG). On the other hand, monomethylarsonous acid (MMA{sup III}), a hydrolysis product of MADG, was not methylated to dimethyl arsenical by Cyt19. These results suggest that As-GSH complexes such as ATG and MADG were converted by Cyt19 to MADG and DMAG, respectively. Both MADG and DMAG were unstable in solution when the GSH concentration was lower than 1 mM, and were hydrolyzed and oxidized to MMA{sup V} and DMA{sup V}, respectively. Metabolism of iAs{sup III} to methylated arsenicals by Cyt19 was via ATG and MADG rather than by oxidative methylation of iAs{sup III} and MMA{sup III}. (orig.)
Polyamine metabolism in the kidneys of castrated and testosterone-treated mice after administration of methylglyoxal bis(guanylhydrazone).

Science.gov (United States)

Henningsson, S; Persson, L; Rosengren, E

1979-02-01

The effects of methylglyoxal bis(guanylhydrazone) on S-adenosyl-L-methionine decarboxylase (EC 4.1.1.50) activity were studied in the mouse kidney stimulated to growth by testosterone administration. The drug was found a potent inhibitor of the enzyme in vitrol Administration of methylglyoxal bis(guanylhydrazone) in vivo resulted in a transient inhibition followed by a strong enhancement of the enzyme activity. Dialysis of the kidney extract, to remove remaining methylglyoxal bis(guanylhydrazone), revealed a great and rapid increase in the activity of S-adenosyl-L-methionine decarboxylase. Injections of testosterone to castrated mice resulted in a marked increase in kidney weight and an accumulation of renal putrescine, spermidine and spermine. These effects of testosterone could not be blocked by simultaneous injections of methylglyoxal bis(guanylhydrazone). It appears that due to secondary effects by which the inhibition of methylglyoxal bis(guanylhydrazone) on S-adenosyl-L-methionine decarboxylase activity is circumvented the inhibitor seems to be of uncertain value in attempts to decrease selectively the in vivo levels of polyamines.
Choline and methionine differentially alter methyl carbon metabolism in bovine neonatal hepatocytes.

Science.gov (United States)

Chandler, Tawny L; White, Heather M

2017-01-01

Intersections in hepatic methyl group metabolism pathways highlights potential competition or compensation of methyl donors. The objective of this experiment was to examine the expression of genes related to methyl group transfer and lipid metabolism in response to increasing concentrations of choline chloride (CC) and DL-methionine (DLM) in primary neonatal hepatocytes that were or were not exposed to fatty acids (FA). Primary hepatocytes isolated from 4 neonatal Holstein calves were maintained as monolayer cultures for 24 h before treatment with CC (61, 128, 2028, and 4528 μmol/L) and DLM (16, 30, 100, 300 μmol/L), with or without a 1 mmol/L FA cocktail in a factorial arrangement. After 24 h of treatment, media was collected for quantification of reactive oxygen species (ROS) and very low-density lipoprotein (VLDL), and cell lysates were collected for quantification of gene expression. No interactions were detected between CC, DLM, or FA. Both CC and DLM decreased the expression of methionine adenosyltransferase 1A (MAT1A). Increasing CC did not alter betaine-homocysteine S-methyltranferase (BHMT) but did increase 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) and methylenetetrahydrofolate reductase (MTHFR) expression. Increasing DLM decreased expression of BHMT and MTR, but did not affect MTHFR. Expression of both phosphatidylethanolamine N-methyltransferase (PEMT) and microsomal triglyceride transfer protein (MTTP) were decreased by increasing CC and DLM, while carnitine palmitoyltransferase 1A (CPT1A) was unaffected by either. Treatment with FA decreased the expression of MAT1A, MTR, MTHFR and tended to decrease PEMT but did not affect BHMT and MTTP. Treatment with FA increased CPT1A expression. Increasing CC increased secretion of VLDL and decreased the accumulation of ROS in media. Within neonatal bovine hepatocytes, choline and methionine differentially regulate methyl carbon pathways and suggest that choline may play a critical role in
Selective and membrane-permeable small molecule inhibitors of nicotinamide N-methyltransferase reverse high fat diet-induced obesity in mice.

Science.gov (United States)

Neelakantan, Harshini; Vance, Virginia; Wetzel, Michael D; Wang, Hua-Yu Leo; McHardy, Stanton F; Finnerty, Celeste C; Hommel, Jonathan D; Watowich, Stanley J

2018-01-01

There is a critical need for new mechanism-of-action drugs that reduce the burden of obesity and associated chronic metabolic comorbidities. A potentially novel target to treat obesity and type 2 diabetes is nicotinamide-N-methyltransferase (NNMT), a cytosolic enzyme with newly identified roles in cellular metabolism and energy homeostasis. To validate NNMT as an anti-obesity drug target, we investigated the permeability, selectivity, mechanistic, and physiological properties of a series of small molecule NNMT inhibitors. Membrane permeability of NNMT inhibitors was characterized using parallel artificial membrane permeability and Caco-2 cell assays. Selectivity was tested against structurally-related methyltransferases and nicotinamide adenine dinucleotide (NAD + ) salvage pathway enzymes. Effects of NNMT inhibitors on lipogenesis and intracellular levels of metabolites, including NNMT reaction product 1-methylnicotianamide (1-MNA) were evaluated in cultured adipocytes. Effects of a potent NNMT inhibitor on obesity measures and plasma lipid were assessed in diet-induced obese mice fed a high-fat diet. Methylquinolinium scaffolds with primary amine substitutions displayed high permeability from passive and active transport across membranes. Importantly, methylquinolinium analogues displayed high selectivity, not inhibiting related SAM-dependent methyltransferases or enzymes in the NAD + salvage pathway. NNMT inhibitors reduced intracellular 1-MNA, increased intracellular NAD + and S-(5'-adenosyl)-l-methionine (SAM), and suppressed lipogenesis in adipocytes. Treatment of diet-induced obese mice systemically with a potent NNMT inhibitor significantly reduced body weight and white adipose mass, decreased adipocyte size, and lowered plasma total cholesterol levels. Notably, administration of NNMT inhibitors did not impact total food intake nor produce any observable adverse effects. These results support development of small molecule NNMT inhibitors as therapeutics to
Effect of certain active components from traditional Chinese medicinal herbs on Aβ secretion rate with L-[35S]-Methionine

International Nuclear Information System (INIS)

Hu Yaer; Zhang Naizheng; Li Aimin; Xia Zongqin

2006-01-01

To observe the effect of certain active components from traditional Chinese medicinal herbs on Aβ secretion rates with L-[ 35 S]-Methionine, β-amyloid peptide (Aβ) in SK-N-SH cell lines stably transfected with APP695 was metabolically labeled with L-[ 35 S]-Methionine. the supernatant from culture medium was immunoprecipitated with monoclonal antibody against Aβ 22-35 , Western blot was carried out, and the gray density of Aβ band in the autoradiograph was measured by an image analysis system. The active components from certain traditional Chinese medicinal herbs (ZMS from Zhimu and AST and HT from Huangqi) were added to the culture medium at a final concentration of 10 -5 mol/L. An Aβ band in the autoradiograph was clearly viewed in the culture medium after 24 h incorporation of [ -35 S]-Methionine which represent the secretion rate of Aβ by the cells. One of the 3 tested components (AST) could significantly reduce the Aβ secretion rate while the other two showed no effect. The preliminary result showed that certain active component from traditional Chinese medicines could decrease the Aβ secretion rate but other active components could not. Combined use of the AST and ZMS was more effective than single AST. (authors)
A common transport system for methionine, L-methionine-DL-sulfoximine (MSX), and phosphinothricin (PPT) in the diazotrophic cyanobacterium Nostoc muscorum.

Science.gov (United States)

Singh, Arvind Kumar; Syiem, Mayashree B; Singh, Rajkumar S; Adhikari, Samrat; Rai, Amar Nath

2008-05-01

We present evidence, for the first time, of the occurrence of a transport system common for amino acid methionine, and methionine/glutamate analogues L-methionine-DL-sulfoximine (MSX) and phosphinothricin (PPT) in cyanobacterium Nostoc muscorum. Methionine, which is toxic to cyanobacterium, enhanced its nitrogenase activity at lower concentrations. The cyanobacterium showed a biphasic pattern of methionine uptake activity that was competitively inhibited by the amino acids alanine, isoleucine, leucine, phenylalanine, proline, valine, glutamine, and asparagine. The methionine/glutamate analogue-resistant N. muscorum strains (MSX-R and PPT-R strains) also showed methionine-resistant phenotype accompanied by a drastic decrease in 35S methionine uptake activity. Treatment of protein extracts from these mutant strains with MSX and PPT reduced biosynthetic glutamine synthetase (GS) activity only in vitro and not in vivo. This finding implicated that MSX- and PPT-R phenotypes may have arisen due to a defect in their MSX and PPT transport activity. The simultaneous decrease in methionine uptake activity and in vitro sensitivity toward MSX and PPT of GS protein in MSX- and PPT-R strains indicated that methionine, MSX, and PPT have a common transport system that is shared by other amino acids as well in N. muscorum. Such information can become useful for isolation of methionine-producing cyanobacterial strains.
Structure and Mechanism of the Rebeccamycin Sugar 4'-O-Methyltransferase RebM

Energy Technology Data Exchange (ETDEWEB)

Singh, Shanteri; McCoy, Jason G.; Zhang, Changsheng; Bingman, Craig A.; Phillips, Jr., George N.; Thorson, Jon S. (UW)

2008-12-12

The 2.65-{angstrom} crystal structure of the rebeccamycin 4'-O-methyltransferase RebM in complex with S-adenosyl-l-homocysteine revealed RebM to adopt a typical S-adenosylmethionine-binding fold of small molecule O-methyltransferases (O-MTases) and display a weak dimerization domain unique to MTases. Using this structure as a basis, the RebM substrate binding model implicated a predominance of nonspecific hydrophobic interactions consistent with the reported ability of RebM to methylate a wide range of indolocarbazole surrogates. This model also illuminated the three putative RebM catalytic residues (His{sup 140/141} and Asp{sup 166}) subsequently found to be highly conserved among sequence-related natural product O-MTases from GC-rich bacteria. Interrogation of these residues via site-directed mutagenesis in RebM demonstrated His{sup 140} and Asp{sup 166} to be most important for catalysis. This study reveals RebM to be a member of the general acid/base-dependent O-MTases and, as the first crystal structure for a sugar O-MTase, may also present a template toward the future engineering of natural product MTases for combinatorial applications.
Crystal structures of the SAM-III/S[subscript MK] riboswitch reveal the SAM-dependent translation inhibition mechanism

Energy Technology Data Exchange (ETDEWEB)

Lu, C.; Smith, A.M.; Fuchs, R.T.; Ding, F.; Rajashankar, K.; Henkin, T.M.; Ke, A. (Cornell); (OSU)

2010-01-07

Three distinct classes of S-adenosyl-L-methionine (SAM)-responsive riboswitches have been identified that regulate bacterial gene expression at the levels of transcription attenuation or translation inhibition. The SMK box (SAM-III) translational riboswitch has been identified in the SAM synthetase gene in members of the Lactobacillales. Here we report the 2.2-{angstrom} crystal structure of the Enterococcus faecalis SMK box riboswitch. The Y-shaped riboswitch organizes its conserved nucleotides around a three-way junction for SAM recognition. The Shine-Dalgarno sequence, which is sequestered by base-pairing with the anti-Shine-Dalgarno sequence in response to SAM binding, also directly participates in SAM recognition. The riboswitch makes extensive interactions with the adenosine and sulfonium moieties of SAM but does not appear to recognize the tail of the methionine moiety. We captured a structural snapshot of the SMK box riboswitch sampling the near-cognate ligand S-adenosyl-L-homocysteine (SAH) in which SAH was found to adopt an alternative conformation and fails to make several key interactions.
Characterization of the Candida albicans Amino Acid Permease Family: Gap2 Is the Only General Amino Acid Permease and Gap4 Is an S-Adenosylmethionine (SAM) Transporter Required for SAM-Induced Morphogenesis

Czech Academy of Sciences Publication Activity Database

Kraidlová, Lucie; Schrevens, S.; Tournu, H.; Van Zeebroeck, G.; Sychrová, Hana; Van Dijck, P.

2016-01-01

Roč. 1, č. 6 (2016), č. článku e00284-16. ISSN 2379-5042 R&D Projects: GA ČR(CZ) GA16-03398S Institutional support: RVO:67985823 Keywords : Candida albicans * GAP1 * S-adenosyl methionine * general amino acid permease * morphogenesis Subject RIV: EE - Microbiology, Virology
The effects of an L-methionine combination supplement on ...

African Journals Online (AJOL)

Interventions. L-methionine combination supplement (L-methionine, vitamin B6, vitamin B12, folic acid and magnesium) or placebo containing potato starch. Main outcome measures. Incidence of URTS was recorded during the runner's preparation for an ultramarathon race (75 days) and recovery from the same (75 days).
Suppression of LFA-1 expression by spermine is associated with enhanced methylation of ITGAL, the LFA-1 promoter area.

Directory of Open Access Journals (Sweden)

Yoshihiko Kano

Full Text Available Spermine and spermidine, natural polyamines, suppress lymphocyte function-associated antigen 1 (LFA-1 expression and its associated cellular functions through mechanisms that remain unknown. Inhibition of ornithine decarboxylase, which is required for polyamine synthesis, in Jurkat cells by 3 mM D,L-alpha-difluoromethylornithine hydrochloride (DFMO significantly decreased spermine and spermidine concentrations and was associated with decreased DNA methyltransferase (Dnmt activity, enhanced demethylation of the LFA-1 gene (ITGAL promoter area, and increased CD11a expression. Supplementation with extracellular spermine (500 µM of cells pretreated with DFMO significantly increased polyamine concentrations, increased Dnmt activity, enhanced methylation of the ITGAL promoter, and decreased CD11a expression. It has been shown that changes in intracellular polyamine concentrations affect activities of -adenosyl-L-methionine-decaroboxylase, and, as a result, affect concentrations of the methyl group donor, S-adenosylmethionine (SAM, and of the competitive Dnmt inhibitor, decarboxylated SAM. Additional treatments designed to increase the amount of SAM and decrease the amount of decarboxylated SAM-such as treatment with methylglyoxal bis-guanylhydrazone (an inhibitor of S-adenosyl-L-methionine-decaroboxylase and SAM supplementation-successfully decreased CD11a expression. Western blot analyses revealed that neither DFMO nor spermine supplementation affected the amount of active Ras-proximate-1, a member of the Ras superfamily of small GTPases and a key protein for regulation of CD11a expression. The results of this study suggest that polyamine-induced suppression of LFA-1 expression occurs via enhanced methylation of ITGAL.
Methionine kinetics in adult men: effects of dietary betaine on L-[2H3-methyl-1-13C]methionine

International Nuclear Information System (INIS)

Storch, K.J.; Wagner, D.A.; Young, V.R.

1991-01-01

The effects of a daily 3-g supplement of betaine on kinetic aspects of L-[2H3-methyl-1-13C]methionine (MET) metabolism in healthy young adult men were explored. Four groups of four subjects each were given a control diet, based on an L-amino acid mixture supplying 29.5 and 21.9 mg.kg-1.d-1 of L-methionine and L-cystine for 4 d before the tracer study, conducted on day 5 during the fed state. Two groups received the control diet and two groups received the betaine supplement. Tracer was given intravenously (iv) or orally. The transmethylation rate of MET (TM), homocysteine remethylation (RM), and oxidation of methionine were estimated from plasma methionine labeling and 13C enrichment of expired air. RM tended to increase (P = 0.14) but the TM and methionine oxidation were significantly (P less than 0.05) higher after betaine supplementation when estimated with the oral tracer. No differences were detected with the intravenous tracer. Methionine concentration in plasma obtained from blood taken from subjects in the fed state was higher (P less than 0.01) with betaine supplementation. These results suggest that excess methyl-group intake may increase the dietary requirement for methionine
The tylosin resistance gene tlrB of Streptomyces fradiae encodes a methyltransferase that targets G748 in 23S rRNA

DEFF Research Database (Denmark)

Liu, M; Kirpekar, F; Van Wezel, G P

2000-01-01

tlrB is one of four resistance genes encoded in the operon for biosynthesis of the macrolide tylosin in antibiotic-producing strains of Streptomyces fradiae. Introduction of tlrB into Streptomyces lividans similarly confers tylosin resistance. Biochemical analysis of the rRNA from the two...... is dependent on the presence of the methyl group donor, S-adenosyl methionine. Analysis of the 74-mer RNA substrate by biochemical and mass spectrometric methods shows that TlrB adds a single methyl group to the base of G748. Homologues of TlrB in other bacteria have been revealed through database searches...

1H NMR studies of substrate hydrogen exchange reactions catalyzed by L-methionine gamma-lyase

International Nuclear Information System (INIS)

Esaki, N.; Nakayama, T.; Sawada, S.; Tanaka, H.; Soda, K.

1985-01-01

Hydrogen exchange reactions of various L-amino acids catalyzed by L-methionine gamma-lyase (EC 4.4.1.11) have been studied. The enzyme catalyzes the rapid exchange of the alpha- and beta-hydrogens of L-methionine and S-methyl-L-cysteine with deuterium from the solvent. The rate of alpha-hydrogen exchange was about 40 times faster than that of the enzymatic elimination reaction of the sulfur-containing amino acids. The enzyme also catalyzes the exchange reaction of alpha- and beta-hydrogens of the straight-chain L-amino acids which are not susceptible to elimination. The exchange rates of the alpha-hydrogen and the total beta-hydrogens of L-alanine and L-alpha-aminobutyrate with deuterium followed first-order kinetics. For L-norvaline, L-norleucine, S-methyl-L-cysteine, and L-methionine, the rate of alpha-hydrogen exchange followed first-order kinetics, but the rate of total beta-hydrogen exchange decreased due to a primary isotope effect at the alpha-position. L-Phenylalanine and L-tryptophan slowly underwent alpha-hydrogen exchange. The pro-R hydrogen of glycine was deuterated stereospecifically
Production of FAME biodiesel in E. coli by direct methylation with an insect enzyme.

Science.gov (United States)

Sherkhanov, Saken; Korman, Tyler P; Clarke, Steven G; Bowie, James U

2016-04-07

Most biodiesel currently in use consists of fatty acid methyl esters (FAMEs) produced by transesterification of plant oils with methanol. To reduce competition with food supplies, it would be desirable to directly produce biodiesel in microorganisms. To date, the most effective pathway for the production of biodiesel in bacteria yields fatty acid ethyl esters (FAEEs) at up to ~1.5 g/L. A much simpler route to biodiesel produces FAMEs by direct S-adenosyl-L-methionine (SAM) dependent methylation of free fatty acids, but FAME production by this route has been limited to only ~16 mg/L. Here we employ an alternative, broad spectrum methyltransferase, Drosophila melanogaster Juvenile Hormone Acid O-Methyltransferase (DmJHAMT). By introducing DmJHAMT in E. coli engineered to produce medium chain fatty acids and overproduce SAM, we obtain medium chain FAMEs at titers of 0.56 g/L, a 35-fold increase over titers previously achieved. Although considerable improvements will be needed for viable bacterial production of FAMEs and FAEEs for biofuels, it may be easier to optimize and transport the FAME production pathway to other microorganisms because it involves fewer enzymes.
S-Adenosyl-L-Homocysteine Hydrolase Inhibition by a Synthetic Nicotinamide Cofactor Biomimetic

Directory of Open Access Journals (Sweden)

Lyn L. Kailing

2018-03-01

Full Text Available S-adenosyl-L-homocysteine (SAH hydrolases (SAHases are involved in the regulation of methylation reactions in many organisms and are thus crucial for numerous cellular functions. Consequently, their dysregulation is associated with severe health problems. The SAHase-catalyzed reaction is reversible and both directions depend on the redox activity of nicotinamide adenine dinucleotide (NAD+ as a cofactor. Therefore, nicotinamide cofactor biomimetics (NCB are a promising tool to modulate SAHase activity. In the present in vitro study, we investigated 10 synthetic truncated NAD+ analogs against a SAHase from the root-nodulating bacterium Bradyrhizobium elkanii. Among this set of analogs, one was identified to inhibit the SAHase in both directions. Isothermal titration calorimetry (ITC and crystallography experiments suggest that the inhibitory effect is not mediated by a direct interaction with the protein. Neither the apo-enzyme (i.e., deprived of the natural cofactor, nor the holo-enzyme (i.e., in the NAD+-bound state were found to bind the inhibitor. Yet, enzyme kinetics point to a non-competitive inhibition mechanism, where the inhibitor acts on both, the enzyme and enzyme-SAH complex. Based on our experimental results, we hypothesize that the NCB inhibits the enzyme via oxidation of the enzyme-bound NADH, which may be accessible through an open molecular gate, leaving the enzyme stalled in a configuration with oxidized cofactor, where the reaction intermediate can be neither converted nor released. Since the reaction mechanism of SAHase is quite uncommon, this kind of inhibition could be a viable pharmacological route, with a low risk of off-target effects. The NCB presented in this work could be used as a template for the development of more potent SAHase inhibitors.
Targeting S-adenosylmethionine biosynthesis with a novel allosteric inhibitor of Mat2A

Energy Technology Data Exchange (ETDEWEB)

Quinlan, Casey L.; Kaiser, Stephen E.; Bolaños, Ben; Nowlin, Dawn; Grantner, Rita; Karlicek-Bryant, Shannon; Feng, Jun Li; Jenkinson, Stephen; Freeman-Cook, Kevin; Dann, Stephen G.; Wang, Xiaoli; Wells, Peter A.; Fantin, Valeria R.; Stewart, Al E.; Grant, Stephan K. (Pfizer)

2017-05-29

S-Adenosyl-L-methionine (SAM) is an enzyme cofactor used in methyl transfer reactions and polyamine biosynthesis. The biosynthesis of SAM from ATP and L-methionine is performed by the methionine adenosyltransferase enzyme family (Mat; EC 2.5.1.6). Human methionine adenosyltransferase 2A (Mat2A), the extrahepatic isoform, is often deregulated in cancer. We identified a Mat2A inhibitor, PF-9366, that binds an allosteric site on Mat2A that overlaps with the binding site for the Mat2A regulator, Mat2B. Studies exploiting PF-9366 suggested a general mode of Mat2A allosteric regulation. Allosteric binding of PF-9366 or Mat2B altered the Mat2A active site, resulting in increased substrate affinity and decreased enzyme turnover. These data support a model whereby Mat2B functions as an inhibitor of Mat2A activity when methionine or SAM levels are high, yet functions as an activator of Mat2A when methionine or SAM levels are low. The ramification of Mat2A activity modulation in cancer cells is also described.
S-adenosylmethionine decarboxylase from baker's yeast.

Science.gov (United States)

Pösö, H; Sinervirta, R; Jänne, J

1975-01-01

1. S-Adenosyl-L-methionine decarboxylase (S-adenosyl-L-methionine carboxy-lyase, EC 4.1.1.50) was purified more than 1100-fold from extracts of Saccharomyces cerevisiae by affinity chromatography on columns of Sepharose containing covalently bound methylglyoxal bis(guanylhydrazone) (1,1'[(methylethanediylidene)dinitrilo]diguanidine) [Pegg, (1974) Biochem J. 141, 581-583]. The final preparation appeared to be homogeneous on polyacrylamide-gel electrophoresis at pH 8.4. 2. S-Adenosylmethionine decarboxylase activity was completely separated from spermidine synthase activity [5'-deoxyadenosyl-(5'),3-aminopropyl-(1),methylsulphonium-salt-putrescine 3-aminopropyltransferase, EC 2.5.1.16] during the purification procedure. 3. Adenosylmethionine decarboxylase activity from crude extracts of baker's yeast was stimulated by putrescine, 1,3-diamino-propane, cadaverine (1,5-diaminopentane) and spermidine; however, the purified enzyme, although still stimulated by the diamines, was completely insensitive to spermidine. 4. Adenosylmethionine decarboxylase has an apparent Km value of 0.09 mM for adenosylmethionine in the presence of saturating concentrations of putrescine. The omission of putrescine resulted in a five-fold increase in the apparent Km value for adenosylmethionine. 5. The apparent Ka value for putrescine, as the activator of the reaction, was 0.012 mM. 6. Methylglyoxal bis(guanylhydrazone) and S-methyladenosylhomocysteamine (decarboxylated adenosylmethionine) were powerful inhibitors of the enzyme. 7. Adenosylmethionine decarboxylase from baker's yeast was inhibited by a number of conventional carbonyl reagents, but in no case could the inhibition be reversed with exogenous pyridoxal 5'-phosphate. PMID:1108876
RNA-Seq and iTRAQ Reveal the Dwarfing Mechanism of Dwarf Polish Wheat (Triticum polonicum L.).

Science.gov (United States)

Wang, Yi; Xiao, Xue; Wang, Xiaolu; Zeng, Jian; Kang, Houyang; Fan, Xing; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong

2016-01-01

The dwarfing mechanism of Rht-dp in dwarf Polish wheat (DPW) is unknown. Each internode of DPW was significantly shorter than it in high Polish wheat (HPW), and the dwarfism was insensitive to photoperiod, abscisic acid (ABA), gibberellin (GA), cytokinin (CK), auxin and brassinolide (BR). To understand the mechanism, three sets of transcripts, DPW, HPW, and a chimeric set (a combination of DPW and HPW), were constructed using RNA sequencing (RNA-Seq). Based on the chimeric transcripts, 2,446 proteins were identified using isobaric tags for relative and absolute quantification (iTRAQ). A total of 108 unigenes and 12 proteins were considered as dwarfism-related differentially expressed genes (DEGs) and differentially expressed proteins (DEPs), respectively. Among of these DEGs and DEPs, 6 DEGs and 6 DEPs were found to be involved in flavonoid and S-adenosyl-methionine (SAM) metabolisms; 5 DEGs and 3 DEPs were involved in cellulose metabolism, cell wall plasticity and cell expansion; 2 DEGs were auxin transporters; 2 DEPs were histones; 1 DEP was a peroxidase. These DEGs and DEPs reduced lignin and cellulose contents, increased flavonoid content, possibly decreased S-adenosyl-methionine (SAM) and polyamine contents and increased S-adenosyl-L-homocysteine hydrolase (SAHH) content in DPW stems, which could limit auxin transport and reduce extensibility of the cell wall, finally limited cell expansion (the cell size of DPW was significantly smaller than HPW cells) and caused dwarfism in DPW.
A common mutation in the 5,10-methylenetetrahydrofolate reductase gene affects genomic DNA methylation through an interaction with folate status

Science.gov (United States)

Friso, Simonetta; Choi, Sang-Woon; Girelli, Domenico; Mason, Joel B.; Dolnikowski, Gregory G.; Bagley, Pamela J.; Olivieri, Oliviero; Jacques, Paul F.; Rosenberg, Irwin H.; Corrocher, Roberto; Selhub, Jacob

2002-01-01

DNA methylation, an essential epigenetic feature of DNA that modulates gene expression and genomic integrity, is catalyzed by methyltransferases that use the universal methyl donor S-adenosyl-l-methionine. Methylenetetrahydrofolate reductase (MTHFR) catalyzes the synthesis of 5-methyltetrahydrofolate (5-methylTHF), the methyl donor for synthesis of methionine from homocysteine and precursor of S-adenosyl-l-methionine. In the present study we sought to determine the effect of folate status on genomic DNA methylation with an emphasis on the interaction with the common C677T mutation in the MTHFR gene. A liquid chromatography/MS method for the analysis of nucleotide bases was used to assess genomic DNA methylation in peripheral blood mononuclear cell DNA from 105 subjects homozygous for this mutation (T/T) and 187 homozygous for the wild-type (C/C) MTHFR genotype. The results show that genomic DNA methylation directly correlates with folate status and inversely with plasma homocysteine (tHcy) levels (P < 0.01). T/T genotypes had a diminished level of DNA methylation compared with those with the C/C wild-type (32.23 vs.62.24 ng 5-methylcytosine/μg DNA, P < 0.0001). When analyzed according to folate status, however, only the T/T subjects with low levels of folate accounted for the diminished DNA methylation (P < 0.0001). Moreover, in T/T subjects DNA methylation status correlated with the methylated proportion of red blood cell folate and was inversely related to the formylated proportion of red blood cell folates (P < 0.03) that is known to be solely represented in those individuals. These results indicate that the MTHFR C677T polymorphism influences DNA methylation status through an interaction with folate status. PMID:11929966
Isolation of L-methionine-enriched mutant of a methylotrophic yeast, Candida boidinii No.2201

International Nuclear Information System (INIS)

Tani, Y.; Lim, W.J.; Yang, H.C.

1988-01-01

Six strains of methylotrophic yeast were examined for production of L-methionine-enriched cells. Candida boidinii (kloeckera sp.) No. 2201,which accumulated 0.54 mg/g-dry cell weight (DCW) of free L-methionine (pool methionine), was selected as the parental strain for breeding L-methionine-rich mutants. Ethionine-resistant mutants were derived from the strain by UV irradiation. A mutant strain, E500-78,which was resistant to 500 μg/ml of DL-ethionine, accumulated 6.02 mg/g-DCW of pool methionine. The culture conditions for mutant strain E500-78 to increase pool methionine accumulation were optimized. As a result, the mutant strain accumulated 8.80 mg/g-DCW of pool methionine and contained 16.02 mg/g-DCW total methionine
Crystal growth and structure of L-methionine L-methioninium hydrogen maleate-a new NLO material

International Nuclear Information System (INIS)

Natarajan, Subramanian; Rajan Devi, Neelamagam; Britto Dhas, Sathiya Dhas Martin; Athimoolam, Shanmuganarayanan

2008-01-01

A new organic nonlinear optical (NLO) crystal from the amino acid family, viz., L-methionine L-methioninium hydrogen maleate (LMMM), has been grown by slow evaporation method from aqueous solution. Bulk crystals were grown using submerged seed solution method. The structure was elucidated using the single crystal x-ray diffraction data. The compound crystallized in the space group P2 1 and the unit cell contains a protonated L-methioninium cation and a zwitterionic methionine residue plus a maleate anion. The backbone conformation angles Ψ 1 and Ψ 2 are in cis and trans configurations for both the methionine and methioninium residues, respectively. Amino and carboxyl groups of the methioninium and methionine residues are connected through N-H...O hydrogen bonds leading to a ring R 2 2 (10) motif.
The Role of Catechol-O-Methyltransferase (COMT Gene in the Etiopathogenesis of Schizophrenia

Directory of Open Access Journals (Sweden)

Ceren Acar

2014-09-01

Full Text Available Genetic factors in the risk of developing schizophrenia is of great importance. With the help of the advances in the field of genetics in recent years by using linkage analysis several genes have been identified that may be a risk factor in schizophrenia. Several association studies have been performed in many different populations on the candidate susceptibility genes that were defined in previous studies. However, these studies give controversial results in different countries with different populations, and there are problems in obtaining replicable results. In this review we aimed to focus on the genetic basis of schizophrenia and the relationship between schizophrenia and catechol-O-methyltransferase (COMT gene. COMT encodes an enzyme molecule which has an important function in dopamine pathways. It has great importance in catecholamine metabolism and pharmacology and genetic mechanism of catechol metabolism variations and their clinical consequences. COMT transfers the methyl group from S-adenosyl-methionine to the hydroxyl group of catechol nucleus (such as dopamine, norepinephrine or catechol estrogen. Genetic variations found in COMT gene are associated with a broad spectrum of clinical phenotype including psychiatric disorders or estrogen related cancers. Several groups have performed studies on the relationship between schizophrenia and COMT. The most commonly studied polymorphism in COMT gene is rs4680 and it causes a valine methionine conversion at codon 158. The association studies on this polymorphism in different populations gave both positive and negative results. Schizoprenia is a complex disease caused by the interaction of environmental and genetic factors, while interpreting the genetic data, this fact and the possibility of the presence of different gene products should be taken into account. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2014; 6(3.000: 217-226
A glutamate/aspartate switch controls product specificity in a protein arginine methyltransferase

Energy Technology Data Exchange (ETDEWEB)

Debler, Erik W.; Jain, Kanishk; Warmack, Rebeccah A.; Feng, You; Clarke, Steven G.; Blobel, Günter; Stavropoulos, Pete

2016-02-08

Trypanosoma brucei PRMT7 (TbPRMT7) is a protein arginine methyltransferase (PRMT) that strictly monomethylates various substrates, thus classifying it as a type III PRMT. However, the molecular basis of its unique product specificity has remained elusive. Here, we present the structure of TbPRMT7 in complex with its cofactor product S-adenosyl-L-homocysteine (AdoHcy) at 2.8 Å resolution and identify a glutamate residue critical for its monomethylation behavior. TbPRMT7 comprises the conserved methyltransferase and β-barrel domains, an N-terminal extension, and a dimerization arm. The active site at the interface of the N-terminal extension, methyltransferase, and β-barrel domains is stabilized by the dimerization arm of the neighboring protomer, providing a structural basis for dimerization as a prerequisite for catalytic activity. Mutagenesis of active-site residues highlights the importance of Glu181, the second of the two invariant glutamate residues of the double E loop that coordinate the target arginine in substrate peptides/proteins and that increase its nucleophilicity. Strikingly, mutation of Glu181 to aspartate converts TbPRMT7 into a type I PRMT, producing asymmetric dimethylarginine (ADMA). Isothermal titration calorimetry (ITC) using a histone H4 peptide showed that the Glu181Asp mutant has markedly increased affinity for monomethylated peptide with respect to the WT, suggesting that the enlarged active site can favorably accommodate monomethylated peptide and provide sufficient space for ADMA formation. In conclusion, these findings yield valuable insights into the product specificity and the catalytic mechanism of protein arginine methyltransferases and have important implications for the rational (re)design of PRMTs.
Crystal structure of the homocysteine methyltransferase MmuM from Escherichia coli.

Science.gov (United States)

Li, Kunhua; Li, Gengnan; Bradbury, Louis M T; Hanson, Andrew D; Bruner, Steven D

2016-02-01

Homocysteine S-methyltransferases (HMTs, EC 2.1.1.0) catalyse the conversion of homocysteine to methionine using S-methylmethionine or S-adenosylmethionine as the methyl donor. HMTs play an important role in methionine biosynthesis and are widely distributed among micro-organisms, plants and animals. Additionally, HMTs play a role in metabolite repair of S-adenosylmethionine by removing an inactive diastereomer from the pool. The mmuM gene product from Escherichia coli is an archetypal HMT family protein and contains a predicted zinc-binding motif in the enzyme active site. In the present study, we demonstrate X-ray structures for MmuM in oxidized, apo and metallated forms, representing the first such structures for any member of the HMT family. The structures reveal a metal/substrate-binding pocket distinct from those in related enzymes. The presented structure analysis and modelling of co-substrate interactions provide valuable insight into the function of MmuM in both methionine biosynthesis and cofactor repair. © 2016 Authors; published by Portland Press Limited.
QM/MM Free Energy Simulations of Salicylic Acid Methyltransferase: Effects of Stabilization of TS-like Structures on Substrate Specificity

Energy Technology Data Exchange (ETDEWEB)

Yao, Jianzhuang [University of Tennessee, Knoxville (UTK); Xu, Qin [University of Tennessee, Knoxville (UTK); Chen, Feng [University of Tennessee, Knoxville (UTK); Guo, Hong [University of Tennessee, Knoxville (UTK)

2010-01-01

Salicylic acid methyltransferases (SAMTs) synthesize methyl salicylate (MeSA) using salicylate as the substrate. MeSA synthesized in plants may function as an airborne signal to activate the expression of defense-related genes and could also be a critical mobile signaling molecule that travels from the site of plant infection to establish systemic immunity in the induction of disease resistance. Here the results of QM/MM free energy simulations for the methyl transfer process in Clarkia breweri SAMT (CbSAMT) are reported to determine the origin of the substrate specificity of SAMTs. The free energy barrier for the methyl transfer from S-adenosyl-l-methionine (AdoMet) to 4-hydroxybenzoate in CbSAMT is found to be about 5 kcal/mol higher than that from AdoMet to salicylate, consistent with the experimental observations. It is suggested that the relatively high efficiency for the methylation of salicylate compared to 4-hydroxybenzoate is due, at least in part, to the reason that a part of the stabilization of the transition state (TS) configuration is already reflected in the reactant complex, presumably, through the binding. The results seem to indicate that the creation of the substrate complex (e.g., through mutagenesis and substrate modifications) with its structure closely resembling TS might be fruitful for improving the catalytic efficiency for some enzymes. The results show that the computer simulations may provide important insights into the origin of the substrate specificity for the SABATH family and could be used to help experimental efforts in generating engineered enzymes with altered substrate specificity.
Targeting methionine cycle as a potential therapeutic strategy for immune disorders.

Science.gov (United States)

Li, Heng; Lu, Huimin; Tang, Wei; Zuo, Jianping

2017-08-23

Methionine cycle plays an essential role in regulating many cellular events, especially transmethylation reactions, incorporating the methyl donor S-adenosylmethionine (SAM). The transmethylations and substances involved in the cycle have shown complicated effects and mechanisms on immunocytes developments and activations, and exert crucial impacts on the pathological processes in immune disorders. Areas covered: Methionine cycle has been considered as an effective means of drug developments. This review discussed the role of methionine cycle in immune responses and summarized the potential therapeutic strategies based on the cycle, including SAM analogs, methyltransferase inhibitors, S-adenosylhomocysteine hydrolase (SAHH) inhibitors, adenosine receptors specific agonists or antagonists and homocysteine (Hcy)-lowering reagents, in treating human immunodeficiency virus (HIV) infections, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), systemic sclerosis (SSc) and other immune disorders. Expert opinion: New targets and biomarkers grown out of methionine cycle have developed rapidly in the past decades. However, impacts of epigenetic regulations on immune disorders are unclear and whether the substances in methionine cycle can be clarified as biomarkers remains controversial. Therefore, further elucidation on the role of epigenetic regulations and substances in methionine cycle may contribute to exploring the cycle-derived biomarkers and drugs in immune disorders.
HERBAL METHIONINE (METHIOREP® IMPROVES GROWTH PERFORMANCE OF BROILER CHICKENS WITHOUT AFFECTING CARCASS CHARACTERISTICS AND BLOOD INDICES

Directory of Open Access Journals (Sweden)

O.J. Makinde

2017-05-01

Full Text Available Methiorep®, an herbal methionine premix, which is reported to contain herbal ingredients that mimic the activity of Methionine such as SAMe (S-Adenosyl Methionine and phosphatidyl choline, have recently introduced to Nigeria animal feed industry. An experiment was conducted with 120, one-week-old broilers to evaluate the effect of herbal methionine (methiorep® as substitute for synthetic methionine on growth performance of broiler chickens. Five isocaloric and isonitrogenous diets were formulated and Diet 1 (control, comprised of 0.25% methionine (NRC, 1994 while diet 2, 3, 4 and 5 comprised of 25%, 50%, 75% and 100% Methiorep® as substitute for methionine in the diets. The birds were randomly allocated to five experimental treatments, each treatment was replicated three times with eight birds per pen in a completely randomized design. The study lasted 49-days. The results of growth performance revealed that body weight gain, average feed intake and feed conversion ratio at both starter and finisher phases were not influenced by dietary treatments (P>0.05. However cost per kg feed decreased as the level of Methiorep® increased in the diets (P0.05 by the dietary treatments. It was concluded that Methiorep® can completely substitute for Methionine in the diets of broiler chickens without adverse effect on growth performance, blood profiles and carcass yield of birds.
Platinum(II) complexes with steroidal esters of L-methionine and L-histidine: Synthesis, characterization and cytotoxic activity

Czech Academy of Sciences Publication Activity Database

Kvasnica, Miroslav; Buděšínský, Miloš; Swaczynová, Jana; Pouzar, Vladimír; Kohout, Ladislav

2008-01-01

Roč. 16, č. 7 (2008), s. 3704-3713 ISSN 0968-0896 R&D Projects: GA AV ČR KAN200200651 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50380511 Keywords : steroids * platinum * L-histidin * L-methionin Subject RIV: CC - Organic Chemistry Impact factor: 3.075, year: 2008
Suppression of a methionine synthase by calmodulin under environmental stress in the entomopathogenic fungus Beauveria bassiana.

Science.gov (United States)

Kim, Jiyoung; Oh, Junsang; Yoon, Deok-Hyo; Sung, Gi-Ho

2017-10-01

Methionine synthase (MetE, EC 2.1.1.14) catalyses the final step in the methionine biosynthetic pathway. Methionine biosynthesis plays a major role in protein biogenesis and is the source of S-adenosyl methionine (SAM), the universal donor of methyl groups. In this study, we demonstrated that BbMetE acts as a typical MetE enzyme in the entomopathogenic fungus Beauveria bassiana. In addition, we found that BbMetE binds to calmodulin (CaM) in vitro and in vivo. The functional role of CaM binding to BbMetE was to negatively regulate BbMetE activity in B. bassiana. Our proton-nuclear magnetic resonance data revealed that CaM inhibitor W-7 increases methionine content in B. bassiana, suggesting that CaM negatively regulates the BbMetE activity. Environmental stress stimuli such as salt, H 2 O 2 and heat suppressed BbMetE activity in B. bassiana. W-7 reversed this effect, suggesting that the inhibitory mechanism is mediated through stimulation of CaM activity. Therefore, this work suggests that BbMetE plays an important role in methionine biosynthesis, which is mediated by environmental stress stimuli via the CaM signalling pathway. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.
Drought stress provokes the down-regulation of methionine and ethylene biosynthesis pathways in Medicago truncatula roots and nodules.

Science.gov (United States)

Larrainzar, Estíbaliz; Molenaar, Johanna A; Wienkoop, Stefanie; Gil-Quintana, Erena; Alibert, Bénédicte; Limami, Anis M; Arrese-Igor, Cesar; González, Esther M

2014-09-01

Symbiotic nitrogen fixation is one of the first physiological processes inhibited in legume plants under water-deficit conditions. Despite the progress made in the last decades, the molecular mechanisms behind this regulation are not fully understood yet. Recent proteomic work carried out in the model legume Medicago truncatula provided the first indications of a possible involvement of nodule methionine (Met) biosynthesis and related pathways in response to water-deficit conditions. To better understand this involvement, the drought-induced changes in expression and content of enzymes involved in the biosynthesis of Met, S-adenosyl-L-methionine (SAM) and ethylene in M. truncatula root and nodules were analyzed using targeted approaches. Nitrogen-fixing plants were subjected to a progressive water deficit and a subsequent recovery period. Besides the physiological characterization of the plants, the content of total sulphur, sulphate and main S-containing metabolites was measured. Results presented here show that S availability is not a limiting factor in the drought-induced decline of nitrogen fixation rates in M. truncatula plants and provide evidences for a down-regulation of the Met and ethylene biosynthesis pathways in roots and nodules in response to water-deficit conditions. © 2014 John Wiley & Sons Ltd.
C-11 production with MC-50 cyclotron and synthesis of L-[11C-methyl] methionine

International Nuclear Information System (INIS)

Kim, Sang Wook; Hur, Min Goo; Yang, Seung Dae; Ahn, Soon Hyuk; Chun, Kweon Soo

2003-01-01

L-[ 11 C-methyl] methionine was prepared via no-carrier-added(nca) fast S-alkylation of L-homocysteine with [ 11 C]CH 3 I using solid support (Al 2 O 3 /KF)at room temperature in ethanol. The radiochemical yield of methylation was 90.2%. After reaction, no radiochemical impurity was detected but traces of L-homocysteine precursor were monitored by UV detector. The purification was archived by passing successively through a C 18 and alumina sep-pak. the radiochemical purity of L-[ 11 C-methyl] methionine was over 98% after purification and total elapsed time to prepare was 10min from [ 11 C]CH 3 I delivery
Isozyme-specific enzyme inhibitors. 14. 5'(R)-C-[(L-homocystein-S-yl)methyl]adenosine 5'-(beta,gamma-imidotriphosphate), a potent inhibitor of rat methionine adenosyltransferases.

Science.gov (United States)

Kappler, F; Vrudhula, V M; Hampton, A

1987-09-01

The title compound is a covalent adduct of L-methionine (Met) and beta,gamma-imido-ATP. In its synthesis the N-Boc derivative of 5'(R)-C-(aminomethyl)-N6-benzoyl-5'-O-tosyl-2',3'-O- isopropylidenadenosine was converted by the successive actions of CF3CO2H and HNO2 into the corresponding 5'(R)-C-hydroxymethyl derivative. Treatment of this with disodium L-homocysteinate led to attack of sulfur at C6', apparently via a 5',6'-epoxide, and to total stereoselective inversion at C5' to furnish, after debenzoylation, 5'(R)-C-(L-homocystein-S-ylmethyl)-2',3'-O-isopropylidene ade nosine. The 5' configuration was established by conversion of this into the known 5'(S)-C-methyl-2',3'-O-isopropylidene adenosine with Raney nickel. The alpha-amino acid residue was protected as an N-Boc methyl ester, after which the 5'-hydroxyl was phosphorylated with benzyl phosphate and dicyclohexylcarbodiimide. The phosphoanhydride bond with inorganic imidodiphosphate was then created by established methods. Finally, blocking groups were removed under conditions that gave the desired adduct with no racemization of its L-methionine residue. It was a potent inhibitor [KM(ATP)/Ki = 1080; KM(Met)/Ki = 7.7] of the M-2 (normal tissue) form of rat methionine adenosyltransferase and of the M-T (hepatoma tissue) form [KM(ATP)/Ki = 670; KM(Met)/Ki = 22]. Inhibitions were competitive with respect to ATP or to L-methionine, indicating a dual substrate site mode of binding to the enzyme forms.

Impaired Homocysteine Transmethylation and Protein-Methyltransferase Activity Reduce Expression of Selenoprotein P: Implications for Obesity and Metabolic Syndrome

Science.gov (United States)

Obesity causes Metabolic Syndrome and Type-II Diabetes, disrupting hepatic function, methionine (Met)/homocysteine (Hcy) transmethylation and methyltransferase (PRMT) activities. Selenoprotein P (SEPP1), exported from the liver, is the predominate form of plasma selenium (Se) and the physiological S...
Two Distinct Aerobic Methionine Salvage Pathways Generate Volatile Methanethiol in Rhodopseudomonas palustris

Science.gov (United States)

Miller, Anthony R.; North, Justin A.; Wildenthal, John A.

2018-01-01

ABSTRACT 5′-Methyl-thioadenosine (MTA) is a dead-end, sulfur-containing metabolite and cellular inhibitor that arises from S-adenosyl-l-methionine-dependent reactions. Recent studies have indicated that there are diverse bacterial methionine salvage pathways (MSPs) for MTA detoxification and sulfur salvage. Here, via a combination of gene deletions and directed metabolite detection studies, we report that under aerobic conditions the facultatively anaerobic bacterium Rhodopseudomonas palustris employs both an MTA-isoprenoid shunt identical to that previously described in Rhodospirillum rubrum and a second novel MSP, both of which generate a methanethiol intermediate. The additional R. palustris aerobic MSP, a dihydroxyacetone phosphate (DHAP)-methanethiol shunt, initially converts MTA to 2-(methylthio)ethanol and DHAP. This is identical to the initial steps of the recently reported anaerobic ethylene-forming MSP, the DHAP-ethylene shunt. The aerobic DHAP-methanethiol shunt then further metabolizes 2-(methylthio)ethanol to methanethiol, which can be directly utilized by O-acetyl-l-homoserine sulfhydrylase to regenerate methionine. This is in contrast to the anaerobic DHAP-ethylene shunt, which metabolizes 2-(methylthio)ethanol to ethylene and an unknown organo-sulfur intermediate, revealing functional diversity in MSPs utilizing a 2-(methylthio)ethanol intermediate. When MTA was fed to aerobically growing cells, the rate of volatile methanethiol release was constant irrespective of the presence of sulfate, suggesting a general housekeeping function for these MSPs up through the methanethiol production step. Methanethiol and dimethyl sulfide (DMS), two of the most important compounds of the global sulfur cycle, appear to arise not only from marine ecosystems but from terrestrial ones as well. These results reveal a possible route by which methanethiol might be biologically produced in soil and freshwater environments. PMID:29636438
21 CFR 172.372 - N-Acetyl-L-methionine.

Science.gov (United States)

2010-04-01

... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.372 N-Acetyl-L-methionine. The food additive N-acetyl-L...
CAM and Hepatitis C: A Focus on Herbal Supplements

Science.gov (United States)

... sophora root), chlorella (a type of algae), black cumin (Nigella sativa) , S-adenosyl-L-methionine (SAMe), and thymus ... 184. Prasad AS. Zinc: role in immunity, oxidative stress and chronic inflammation . Current Opinion in Clinical Nutrition ...
Molecular cloning and characterization of juvenile hormone acid methyltransferase in the honey bee, Apis mellifera, and its differential expression during caste differentiation.

Directory of Open Access Journals (Sweden)

Wenfeng Li

Full Text Available Juvenile hormone acid methyltransferase (JHAMT is an enzyme involved in one of the final steps of juvenile hormone biosynthesis in insects. It transfers a methyl group from S-adenosyl-L-methionine (SAM to the carboxyl group of either farnesoic acid (FA or JH acid (JHA. Several genes coding for JHAMT have been cloned and characterized from insects from different orders, and they have been shown to play critical roles in metamorphosis and reproduction. However, the significance of JHAMT in Hymenopteran insects is unknown. We used RACE amplification method to clone JHAMT cDNA from the honey bee, Apis mellifera (AmJHAMT. The full length cDNA of AmJHAMT that we cloned is 1253bp long and encodes a 278-aa protein that shares 32-36% identity with known JHAMTs. A SAM-binding motif, conserved in the SAM-dependent methyltransferase (SAM-MT superfamily, is present in AmJHAMT. Its secondary structure also contains a typical SAM-MT fold. Most of the active sites bound with SAM and substrates (JHA or FA are conserved in AmJHAMT as in other JHAMT orthologs. Phylogenetic analysis clustered AmJHAMT with the other orthologs from Hymenoptera to form a major clade in the phylogenetic tree. Purified recombinant AmJHAMT protein expressed in E. coli was used to produce polyclonal antibodies and to verify the identity of AmJHAMT by immunoblotting and mass spectrometry. Quantitative RT-PCR and immunoblotting analyses revealed that queen larvae contained significantly higher levels of AmJHAMT mRNA and protein than worker larvae during the periods of caste development. The temporal profiles of both AmJHAMT mRNA and protein in queens and workers showed a similar pattern as the JH biosynthesis. These results suggest that the gene that we cloned codes for a functional JHAMT that catalyzes the final reactions of JH biosynthesis in honey bees. In addition, AmJHAMT may play an important role in honey bee caste differentiation.
Practical synthesis of 14C S-ribosyl-L-homocysteine uniformly labelled on the sugar moiety. An enzymatic route from (U-14C) adenosine

International Nuclear Information System (INIS)

Guillerm, G.; Allart, B.

1992-01-01

[(U- 14 C) S-Ribosyl]-L-homocysteine has been prepared enzymatically from (U- 14 C) adenosine in two steps using S-adenosyl homocysteine hydrolase and bacterial S-adenosyl homocysteine nucleosidase as catalysts. (Author)
Structural basis for G9a-like protein lysine methyltransferase inhibition by BIX-01294

Energy Technology Data Exchange (ETDEWEB)

Chang, Yanqi; Zhang, Xing; Horton, John R.; Upadhyay, Anup K.; Spannhoff, Astrid; Liu, Jin; Synder, James P.; Bedford, Mark T.; Cheng, Xiaodong; (Emory-MED); (Emory); (Texas)

2009-03-26

Histone lysine methylation is an important epigenetic mark that regulates gene expression and chromatin organization. G9a and G9a-like protein (GLP) are euchromatin-associated methyltransferases that repress transcription by methylating histone H3 Lys9. BIX-01294 was originally identified as a G9a inhibitor during a chemical library screen of small molecules and has previously been used in the generation of induced pluripotent stem cells. Here we present the crystal structure of the catalytic SET domain of GLP in complex with BIX-01294 and S-adenosyl-L-homocysteine. The inhibitor is bound in the substrate peptide groove at the location where the histone H3 residues N-terminal to the target lysine lie in the previously solved structure of the complex with histone peptide. The inhibitor resembles the bound conformation of histone H3 Lys4 to Arg8, and is positioned in place by residues specific for G9a and GLP through specific interactions.
Safety of methionine, a novel biopesticide, to adult and larval honey bees (Apis mellifera L.).

Science.gov (United States)

Weeks, Emma N I; Schmehl, Daniel R; Baniszewski, Julie; Tomé, Hudson V V; Cuda, James P; Ellis, James D; Stevens, Bruce R

2018-03-01

Methionine is an essential/indispensible amino acid nutrient required by adult and larval honey bees (Apis mellifera L. [Hymenoptera: Apidae]). Bees are unable to rear broods on pollen deficient in methionine, and reportedly behaviorally avoid collecting pollen or nectar from florets deficient in methioinine. In contrast, it has been demonstrated that methionine is toxic to certain pest insects; thus it has been proposed as an effective biopesticide. As an ecofriendly integrated pest management agent, methionine boasts a novel mode of action differentiating it from conventional pesticides, while providing non-target safety. Pesticides that minimize collateral effects on bees are desirable, given the economic and ecological concerns about honey bee health. The aim of the present study was to assess the potential impact of the biopesticide methionine on non-target adult and larval honey bees. Acute contact adult toxicology bioassays, oral adult assessments and chronic larval toxicity assessments were performed as per U.S. Environmental Protection Agency (EPA) requirements. Our results demonstrated that methionine fits the U.S. EPA category of practically nontoxic (i.e. lethal dose to 50% mortality or LD 50 > 11µg/bee) to adult honey bees. The contact LD 50 was > 25µg/bee and the oral LD 50 was > 100µg/bee. Mortality was observed in larval bees that ingested DL-methionine (effective concentration to 50% mortality or EC 50 560µg/bee). Therefore, we conclude that methionine poses little threat to the health of the honey bee, due to unlikely exposure at concentrations shown to elicit toxic effects. Copyright © 2017 Elsevier Inc. All rights reserved.
Synthesis and study of catalytic application of l-methionine protected gold nanoparticles

Science.gov (United States)

Raza, Akif; Javed, Safdar; Qureshi, Muhammad Zahid; khan, Muhammad Usman; Khan, Muhammad Saleem

2017-10-01

Gold nanoparticle is growing class of nanotechnology due to large number of uses. We synthesized stable l-methionine protected gold nanoparticles (AuNps) by in situ reduction of HAuCl4 using sodium borohydrate as reducing and l-methionine as stabilizing agent in an aqueous medium. Different parameters (pH, capping agent, precursor salt, and heating time) were optimized to see the effect on the size of particles. Double beam spectrophotometer was used to carry out the spectroscopic studies. It was observed that pH and concentration of reducing salt are deciding factors in controlling the size and morphology of AuNps. Scanning electron microscopy (SEM) verified the formation of AuNPs as predicted by UV-Vis spectra. The interaction of AuNPs with l-methionine was confirmed by Fourier Transform Infrared (FTIR). The reduction of 4-nitrophenol acted as standard of reaction to check the response of AuNps catalyst. Complete reduction of 4-nitrophenol was accomplished by AuNps sol in just 60 s. Fastest reduction rate was observed with smaller spherical particles. This study concluded that size and shape of AuNps can be monitored by controlling the pH, concentration of capping and reducing agent. It also provides an economical solution to aquatic environment in terms of time saving and use of small volume of catalytic solution for reduction of several other toxic organic pollutants.
Mechanism of oxidation of L-methionine by iron(III)-1,10 ...

Indian Academy of Sciences (India)

Unknown

Abstract. Kinetics and mechanism of oxidation of L-methionine by iron(III)–1,10- phenanthroline complex have been studied in perchloric acid medium. The reaction is first order each in iron(III) and methionine. Increase in [phenanthroline] increases the rate while increase in [HClO4] decreases it. While the reactive species ...
Expanding the clinical and molecular spectrum of PRMT7 mutations: 3 additional patients and review.

Science.gov (United States)

Agolini, E; Dentici, M L; Bellacchio, E; Alesi, V; Radio, F C; Torella, A; Musacchia, F; Tartaglia, M; Dallapiccola, B; Nigro, V; Digilio, M C; Novelli, A

2018-03-01

Protein arginine methyltransferase 7 (PRMT7) is a member of a family of enzymes that catalyze the transfer of methyl groups from S-adenosyl-l-methionine to nitrogen atoms on arginine residues. Arginine methylation is involved in multiple biological processes, such as signal transduction, mRNA splicing, transcriptional control, DNA repair, and protein translocation. Currently, 7 patients have been described harboring compound heterozygous or homozygous variants in the PRMT7 gene, causing a novel intellectual disability syndrome, known as SBIDDS syndrome (Short Stature, Brachydactyly, Intellectual Developmental Disability, and Seizures). We report on 3 additional patients from 2 consanguineous families with severe/moderate intellectual disability, short stature, brachydactyly and dysmorphisms. Exome sequencing revealed 2 novel homozygous mutations in PRMT7. Our findings expand the clinical and molecular spectrum of homozygous PRMT7 mutations, associated to the SBIDDS syndrome, showing a possible correlation between the type of mutation and the severity of the phenotype. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Using Raman spectroscopy to understand the origin of the phase transition observed in the crystalline sulfur based amino acid l-methionine

DEFF Research Database (Denmark)

Lima, José A.; Freire, P.T.C.; Melo, F.E.A.

2013-01-01

We present the Raman spectra of l-methionine (C5 H11 NO2 S) monocrystals obtained in the spectral region ranging from 3200 to 50 cm-1 at temperatures from 20 to 375 K. We investigated the dynamics of the different functional groups in l-methionine and related their behaviour to the structural tra...
A practical and pyrogen-free preparation of 11C-L-methionine in a good manufacturing practice-compliant approach

Directory of Open Access Journals (Sweden)

Kang-Po Li

2017-01-01

Full Text Available Aims: 11C-L-methionine, an amino acid tracer used to delineate certain tumor tissues, has proven to be a prevailing nonfluorodeoxyglucose positron emission tomography (PET radiopharmaceutical. We intended to prepare 11C-L-methionine by following modified synthetic strategies at a rebuilt working area to meet the PET drug current good manufacturing practice (cGMP and Pharmaceutical Inspection Co-operation Scheme (PIC/S regulations. Furthermore, we overcame the problem of pyrogen cross-contamination using a cleaner and more efficient program. Material and Methods: The task of upgrading air filtration equipment was integrated with the set of Web-Based Building Automation system (WebCTRL®. 11C-L-methionine synthesis was carried out in accordance with redesigned methods to meet the requirements of PET drug cGMP. The product quality was tested by a series of quality control tests and was found to be satisfactory. Depyrogenation was carried out by three different methods with different flow rates and flushing durations. The results were examined through limulus amebocyte lysate clotting test. Results: The level of air cleanliness in each section meets the PIC/S GMP standards after the reconstructions. Moreover, after delicate modifications, the radiochemical yield of 11C-L-methionine was 36.20% ± 3.59% (based on 11C-CH3I, n = 7, which is about 10% higher than the average former yield. Besides, the used depyrogenation methods could wipe the bioburden off within 8 h. Conclusions: The modifications done not only offer a good production environment but also protect the products from contamination. The modified approaches in both 11C-L-methionine production and depyrogenation resulted in prominent progress in stability and efficiency as well.
Quantitative proteomics reveals the mechanism and consequence of gliotoxin-mediated dysregulation of the methionine cycle in Aspergillus niger

OpenAIRE

Manzanares-Miralles, Lara; Bayram, Ozgur; Sarikaya-Bayram, Ozlem; Smith, Elizabeth B.; Dolan, Stephen K.; Jones, Gary W.; Doyle, Sean

2016-01-01

Gliotoxin (GT) is a redox-active metabolite, produced by Aspergillus fumigatus,which inhibits the growth of other fungi. Here we demonstrate how Aspergillus niger responds to GT exposure. Quantitative proteomics revealed that GT dysregulated the abundance of 378 proteins including those involved in methionine metabolism and induced de novo abundance of two S-adenosylmethionine (SAM)-dependent methyltransferases. Increased abundance of enzymes S-adenosylhomocysteinase (p = 0.0018) ...
Absorption of l-methionine from the human small intestine

Science.gov (United States)

Schedl, Harold P.; Pierce, Charles E.; Rider, Alan; Clifton, James A.

1968-01-01

Absorption of L-methionine was measured in all parts of the human small intestine using transintestinal intubation and perfusion. In four normal subjects, adsorption was higher in the proximal than in the distal intestine. In two patients with nontropical sprue in relapse, there was a proximal zone of low absorption with higher absorption distally. In all parts of the small intestine, absorption showed rate-limiting kinetics as methionine concentration was increased. In normal subjects, the proximal Km (Michaelis constant) was more than 3 times higher than the distal, which suggests a difference in transport mechanisms between the two segments. PMID:12066784
A L2HGDH initiator methionine codon mutation in a Yorkshire terrier with L-2-hydroxyglutaric aciduria

Directory of Open Access Journals (Sweden)

Farias Fabiana HG

2012-07-01

Full Text Available Abstract Background L-2-hydroxyglutaric aciduria is a metabolic repair deficiency characterized by elevated levels of L-2-hydroxyglutaric acid in urine, blood and cerebrospinal fluid. Neurological signs associated with the disease in humans and dogs include seizures, ataxia and dementia. Case presentation Here we describe an 8 month old Yorkshire terrier that presented with episodes of hyperactivity and aggressive behavior. Between episodes, the dog’s behavior and neurologic examinations were normal. A T2 weighted MRI of the brain showed diffuse grey matter hyperintensity and a urine metabolite screen showed elevated 2-hydroxyglutaric acid. We sequenced all 10 exons and intron-exon borders of L2HGDH from the affected dog and identified a homozygous A to G transition in the initiator methionine codon. The first inframe methionine is at p.M183 which is past the mitochondrial targeting domain of the protein. Initiation of translation at p.M183 would encode an N-terminal truncated protein unlikely to be functional. Conclusions We have identified a mutation in the initiation codon of L2HGDH that is likely to result in a non-functional gene. The Yorkshire terrier could serve as an animal model to understand the pathogenesis of L-2-hydroxyglutaric aciduria and to evaluate potential therapies.
A disulfide-stabilized conformer of methionine synthase reveals an unexpected role for the histidine ligand of the cobalamin cofactor

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Datta, Supratim; Koutmos, Markos; Pattridge, Katherine A.; Ludwig, Martha L.; Matthews, Rowena G. (Michigan)

2008-07-08

B{sub 12}-dependent methionine synthase (MetH) from Escherichia coli is a large modular protein that is alternately methylated by methyltetrahydrofolate to form methylcobalamin and demethylated by homocysteine to form cob(I)alamin. Major domain rearrangements are required to allow cobalamin to react with three different substrates: homocysteine, methyltetrahydrofolate, and S-adenosyl-l-methionine (AdoMet). These same rearrangements appear to preclude crystallization of the wild-type enzyme. Disulfide cross-linking was used to lock a C-terminal fragment of the enzyme into a unique conformation. Cysteine point mutations were introduced at Ile-690 and Gly-743. These cysteine residues span the cap and the cobalamin-binding module and form a cross-link that reduces the conformational space accessed by the enzyme, facilitating protein crystallization. Here, we describe an x-ray structure of the mutant fragment in the reactivation conformation; this conformation enables the transfer of a methyl group from AdoMet to the cobalamin cofactor. In the structure, the axial ligand to the cobalamin, His-759, dissociates from the cobalamin and forms intermodular contacts with residues in the AdoMet-binding module. This unanticipated intermodular interaction is expected to play a major role in controlling the distribution of conformers required for the catalytic and the reactivation cycles of the enzyme.
l-Methionine anti-biofilm activity against Pseudomonas aeruginosa is enhanced by the cystic fibrosis transmembrane conductance regulator potentiator, ivacaftor.

Science.gov (United States)

Cho, Do-Yeon; Lim, Dong-Jin; Mackey, Calvin; Weeks, Christopher G; Peña Garcia, Jaime A; Skinner, Daniel; Grayson, Jessica W; Hill, Harrison S; Alexander, David K; Zhang, Shaoyan; Woodworth, Bradford A

2018-05-01

Biofilms may contribute to refractory chronic rhinosinusitis (CRS), as they lead to antibiotic resistance and failure of effective clinical treatment. l-Methionine is an amino acid with reported biofilm-inhibiting properties. Ivacaftor is a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator with mild antimicrobial activity via inhibition of bacterial DNA gyrase and topoisomerase IV. The objective of this study was to evaluate whether co-treatment with ivacaftor and l-methionine can reduce the formation of Pseudomonas aeruginosa biofilms. P aeruginosa (PAO-1 strain) biofilms were studied in the presence of l-methionine and/or ivacaftor. For static biofilm assays, PAO-1 was cultured in a 48-well plate for 72 hours with stepwise combinations of these agents. Relative biofilm inhibitions were measured according to optical density of crystal violet stain at 590 nm. Live/dead assays (BacTiter-Glo™ assay, Promega) were imaged with laser scanning confocal microscopy. An agar diffusion test was used to confirm antibacterial effects of the drugs. l-Methionine (0.5 μM) significantly reduced PAO-1 biofilm mass (32.4 ± 18.0%; n = 4; p l-methionine (two-way analysis of variane, p = 0.0415) compared with corresponding concentrations of l-methionine alone. Ivacaftor enhanced the anti-biofilm activity of l-methionine against the PAO-1 strain of P aeruginosa. Further studies evaluating the efficacy of ivacaftor/l-methionine combinations for P aeruginosa sinusitis are planned. © 2018 ARS-AAOA, LLC.
Folate promotes S-adenosyl methionine reactions and the microbial methylation cycle and boosts ruminants production and reproduction.

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Abbasi, Imtiaz Hussain Raja; Abbasi, Farzana; Wang, Lamei; Abd El Hack, Mohamed E; Swelum, Ayman A; Hao, Ren; Yao, Junhu; Cao, Yangchun

2018-04-23

Folate has gained significant attention due to its vital role in biological methylation and epigenetic machinery. Folate, or vitamin (B 9 ), is only produced through a de novo mechanism by plants and micro-organisms in the rumen of mature animals. Although limited research has been conducted on folate in ruminants, it has been noted that ruminal synthesis could not maintain folate levels in high yielding dairy animals. Folate has an essential role in one-carbon metabolism and is a strong antiproliferative agent. Folate increases DNA stability, being crucial for DNA synthesis and repair, the methylation cycle, and preventing oxidation of DNA by free radicals. Folate is also critical for cell division, metabolism of proteins, synthesis of purine and pyrimidine, and increasing the de novo delivery of methyl groups and S-adenosylmethionine. However, in ruminants, metabolism of B 12 and B 9 vitamins are closely connected and utilization of folate by cells is significantly affected by B 12 vitamin concentration. Supplementation of folate through diet, particularly in early lactation, enhanced metabolic efficiency, lactational performance, and nutritional quality of milk. Impaired absorption, oxidative degradation, or deficient supply of folate in ruminants affects DNA stability, cell division, homocysteine remethylation to methionine, de novo synthesis of S-adenosylmethionine, and increases DNA hypomethylation, uracil misincorporation into DNA, chromosomal damage, abnormal cell growth, oxidative species, premature birth, low calf weight, placental tube defects, and decreases production and reproduction of ruminant animals. However, more studies are needed to overcome these problems and reduce enormous dietary supplement waste and impaired absorption of folate in ruminants. This review was aimed to highlight the vital role of folic acid in ruminants performance.
Activation of Nrf2 is required for up-regulation of the π class of glutathione S-transferase in rat primary hepatocytes with L-methionine starvation.

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Lin, Ai-Hsuan; Chen, Haw-Wen; Liu, Cheng-Tze; Tsai, Chia-Wen; Lii, Chong-Kuei

2012-07-04

Numerous genes expression is regulated in response to amino acid shortage, which helps organisms adapt to amino acid limitation. The expression of the π class of glutathione (GSH) S-transferase (GSTP), a highly inducible phase II detoxification enzyme, is regulated mainly by activates activating protein 1 (AP-1) binding to the enhancer I of GSTP (GPEI). Here we show the critical role of nuclear factor erythroid-2-related factor 2 (Nrf2) in up-regulating GSTP gene transcription. Primary rat hepatocytes were cultured in a methionine-restricted medium, and immunoblotting and RT-PCR analyses showed that methionine restriction time-dependently increased GSTP protein and mRNA expression over a 48 h period. Nrf2 translocation to the nucleus, nuclear proteins binding to GPEI, and antioxidant response element (ARE) luciferase reporter activity were increased by methionine restriction as well as by l-buthionine sulfoximine (BSO), a GSH synthesis inhibitor. Transfection with Nrf2 siRNA knocked down Nrf2 expression and reversed the methionine-induced GSTP expression and GPEI binding activity. Chromatin immunoprecipitation assay confirmed the binding of Nrf2 to the GPEI. Phosphorylation of extracellular signal-regulated kinase 2 (ERK2) was increased in methionine-restricted and BSO-treated cells. ERK2 siRNA abolished methionine restriction-induced Nrf2 nuclear translocation, GPEI binding activity, ARE-luciferase reporter activity, and GSTP expression. Our results suggest that the up-regulation of GSTP gene transcription in response to methionine restriction likely occurs via the ERK-Nrf2-GPEI signaling pathway.

Methyltransferase-defective avian metapneumovirus vaccines provide complete protection against challenge with the homologous Colorado strain and the heterologous Minnesota strain.

Science.gov (United States)

Sun, Jing; Wei, Yongwei; Rauf, Abdul; Zhang, Yu; Ma, Yuanmei; Zhang, Xiaodong; Shilo, Konstantin; Yu, Qingzhong; Saif, Y M; Lu, Xingmeng; Yu, Lian; Li, Jianrong

2014-11-01

Avian metapneumovirus (aMPV), also known as avian pneumovirus or turkey rhinotracheitis virus, is the causative agent of turkey rhinotracheitis and is associated with swollen head syndrome in chickens. Since its discovery in the 1970s, aMPV has been recognized as an economically important pathogen in the poultry industry worldwide. The conserved region VI (CR VI) of the large (L) polymerase proteins of paramyxoviruses catalyzes methyltransferase (MTase) activities that typically methylate viral mRNAs at guanine N-7 (G-N-7) and ribose 2'-O positions. In this study, we generated a panel of recombinant aMPV (raMPV) Colorado strains carrying mutations in the S-adenosyl methionine (SAM) binding site in the CR VI of L protein. These recombinant viruses were specifically defective in ribose 2'-O, but not G-N-7 methylation and were genetically stable and highly attenuated in cell culture and viral replication in the upper and lower respiratory tracts of specific-pathogen-free (SPF) young turkeys. Importantly, turkeys vaccinated with these MTase-defective raMPVs triggered a high level of neutralizing antibody and were completely protected from challenge with homologous aMPV Colorado strain and heterologous aMPV Minnesota strain. Collectively, our results indicate (i) that aMPV lacking 2'-O methylation is highly attenuated in vitro and in vivo and (ii) that inhibition of mRNA cap MTase can serve as a novel target to rationally design live attenuated vaccines for aMPV and perhaps other paramyxoviruses. Paramyxoviruses include many economically and agriculturally important viruses such as avian metapneumovirus (aMPV), and Newcastle disease virus (NDV), human pathogens such as human respiratory syncytial virus, human metapneumovirus, human parainfluenza virus type 3, and measles virus, and highly lethal emerging pathogens such as Nipah virus and Hendra virus. For many of them, there is no effective vaccine or antiviral drug. These viruses share common strategies for viral gene
The purification, crystallization and preliminary structural characterization of PhzM, a phenazine-modifying methyltransferase from Pseudomonas aeruginosa

International Nuclear Information System (INIS)

Gohain, Neelakshi; Thomashow, Linda S.; Mavrodi, Dmitri V.; Blankenfeldt, Wulf

2006-01-01

PhzM, an S-adenosylmethionine-dependent methyltransferase enzyme that catalyzes a reaction involved in the biosynthesis of pyocyanin in P. aeruginosa, was cloned, overexpressed and crystallized. Data collection from native and selenomethionine-labelled crystals is reported. Pyocyanin, phenazine-1-carboxylic acid and more than 70 related compounds collectively known as phenazines are produced by various species of Pseudomonas, including the fluorescent pseudomonad P. aeruginosa, a Gram-negative opportunistic pathogen in humans and animals. P. aeruginosa synthesizes a characteristic blue water-soluble compound called pyocyanin (1-hydroxy-5-methyl-phenazine). Two enzymes designated PhzM and PhzS are involved in the terminal steps of its synthesis and very little is known about these enzymes. In this study, PhzM, a dimeric S-adenosylmethionine-dependent methyltransferase, was purified and crystallized from PEG 3350/sodium cacodylate/sodium citrate pH 6.5. The crystals belong to space group P1, with unit-cell parameters a = 46.1, b = 61.8, c = 69.6 Å, α = 96.3, β = 106.6, γ = 106.9°. They contain one dimer in the asymmetric unit and diffract to a resolution of 1.8 Å. Anomalous data to 2.3 Å resolution have been collected from seleno-l-methionine-labelled PhzM
Traumatic brain injury alters methionine metabolism: implications for pathophysiology

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Pramod K Dash

2016-04-01

Full Text Available Methionine is an essential proteinogenic amino acid that is obtained from the diet. In addition to its requirement for protein biosynthesis, methionine is metabolized to generate metabolites that play key roles in a number of cellular functions. Metabolism of methionine via the transmethylation pathway generates S-adenosylmethionine (SAM that serves as the principal methyl (-CH3 donor for DNA and histone methyltransferases to regulate epigenetic changes in gene expression. SAM is also required for methylation of other cellular proteins that serve various functions and phosphatidylcholine synthesis that participate in cellular signaling.. Under conditions of oxidative stress, homocysteine (which is derived from SAM enters the transsulfuration pathway to generate glutathione, an important cytoprotective molecule against oxidative damage. As both experimental and clinical studies have shown that traumatic brain injury (TBI alters DNA and histone methylation and causes oxidative stress, we examined if TBI alters the plasma levels of methionine and its metabolites in human patients. Blood samples were collected from healthy volunteers (n = 20 and patients with mild TBI (GCS > 12; n = 20 or severe TBI (GCS < 8; n = 20 within the first 24 hours of injury. The levels of methionine and its metabolites in the plasma samples were analyzed by either liquid chromatography-mass spectrometry or gas chromatography-mass spectrometry (LC-MS or GC-MS. Severe TBI decreased the levels of methionine, SAM, betaine and 2-methylglycine as compared to healthy volunteers, indicating a decrease in metabolism through the transmethylation cycle. In addition, precursors for the generation of glutathione, cysteine and glycine were also found to be decreased as were intermediate metabolites of the gamma-glutamyl cycle (gamma-glutamyl amino acids and 5-oxoproline. Mild TBI also decreased the levels of methionine, α-ketobutyrate, 2 hydroxybutyrate and glycine, albeit to lesser
Structural comparison of tRNA m1A58 methyltransferases revealed different molecular strategies to maintain their oligomeric architecture under extreme conditions

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Guelorget Amandine

2011-12-01

Full Text Available Abstract Background tRNA m1A58 methyltransferases (TrmI catalyze the transfer of a methyl group from S-adenosyl-L-methionine to nitrogen 1 of adenine 58 in the T-loop of tRNAs from all three domains of life. The m1A58 modification has been shown to be essential for cell growth in yeast and for adaptation to high temperatures in thermophilic organisms. These enzymes were shown to be active as tetramers. The crystal structures of five TrmIs from hyperthermophilic archaea and thermophilic or mesophilic bacteria have previously been determined, the optimal growth temperature of these organisms ranging from 37°C to 100°C. All TrmIs are assembled as tetramers formed by dimers of tightly assembled dimers. Results In this study, we present a comparative structural analysis of these TrmIs, which highlights factors that allow them to function over a large range of temperature. The monomers of the five enzymes are structurally highly similar, but the inter-monomer contacts differ strongly. Our analysis shows that bacterial enzymes from thermophilic organisms display additional intermolecular ionic interactions across the dimer interfaces, whereas hyperthermophilic enzymes present additional hydrophobic contacts. Moreover, as an alternative to two bidentate ionic interactions that stabilize the tetrameric interface in all other TrmI proteins, the tetramer of the archaeal P. abyssi enzyme is strengthened by four intersubunit disulfide bridges. Conclusions The availability of crystal structures of TrmIs from mesophilic, thermophilic or hyperthermophilic organisms allows a detailed analysis of the architecture of this protein family. Our structural comparisons provide insight into the different molecular strategies used to achieve the tetrameric organization in order to maintain the enzyme activity under extreme conditions.
Partitioning of L-methionine in aqueous two-phase systems containing poly(propylene glycol) and sodium phosphate salts

International Nuclear Information System (INIS)

Salabat, Alireza; Sadeghi, Rahmat; Moghadam, Somayeh Tiani; Jamehbozorg, Bahman

2011-01-01

Highlights: → Thermodynamics parameters for partitioning of L-methionine in ATPS. → Investigation of different effects on partition coefficient of the amino acid. → Propose the best condition for L-methionine partitioning. - Abstract: The partitioning behavior of L-methionine has been studied in aqueous two-phase systems of (poly(propylene glycol) + sodium phosphate salts + H 2 O) at different temperatures. The salts used were sodium di-hydrogen phosphate (NaH 2 PO 4 ), di-sodium hydrogen phosphate (Na 2 HPO 4 ) and tri-sodium phosphate (Na 3 PO 4 ). The effects of tie line length, salt type, and temperature on the partition coefficient of this amino acid have been studied. In addition, thermodynamic parameters (ΔH o , ΔS o and ΔG o ) as a function of temperature were calculated. The results showed that increasing tie line length led to decreasing of the partition coefficient. We also showed that the partition coefficients of the amino acid in the systems containing Na 3 PO 4 are greater than the other two salts. Moreover, it is verified that increasing temperature led to decreasing the partition coefficient. The experimental partition coefficient data are correlated using a modified virial-type model.
Is L-methionine a trigger factor for Alzheimer?s-like neurodegeneration?: Changes in A? oligomers, tau phosphorylation, synaptic proteins, Wnt signaling and behavioral impairment in wild-type mice

OpenAIRE

Tapia-Rojas, Cheril; Lindsay, Carolina B.; Montecinos-Oliva, Carla; Arrazola, Macarena S.; Retamales, Rocio M.; Bunout, Daniel; Hirsch, Sandra; Inestrosa, Nibaldo C.

2015-01-01

Background L-methionine, the principal sulfur-containing amino acid in proteins, plays critical roles in cell physiology as an antioxidant and in the breakdown of fats and heavy metals. Previous studies suggesting the use of L-methionine as a treatment for depression and other diseases indicate that it might also improve memory and propose a role in brain function. However, some evidence indicates that an excess of methionine can be harmful and can increase the risk of developing Type-2 diabe...
Crystal structure of arginine methyltransferase 6 from Trypanosoma brucei.

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Chongyuan Wang

Full Text Available Arginine methylation plays vital roles in the cellular functions of the protozoan Trypanosoma brucei. The T. brucei arginine methyltransferase 6 (TbPRMT6 is a type I arginine methyltransferase homologous to human PRMT6. In this study, we report the crystal structures of apo-TbPRMT6 and its complex with the reaction product S-adenosyl-homocysteine (SAH. The structure of apo-TbPRMT6 displays several features that are different from those of type I PRMTs that were structurally characterized previously, including four stretches of insertion, the absence of strand β15, and a distinct dimerization arm. The comparison of the apo-TbPRMT6 and SAH-TbPRMT6 structures revealed the fine rearrangements in the active site upon SAH binding. The isothermal titration calorimetry results demonstrated that SAH binding greatly increases the affinity of TbPRMT6 to a substrate peptide derived from bovine histone H4. The western blotting and mass spectrometry results revealed that TbPRMT6 methylates bovine histone H4 tail at arginine 3 but cannot methylate several T. brucei histone tails. In summary, our results highlight the structural differences between TbPRMT6 and other type I PRMTs and reveal that the active site rearrangement upon SAH binding is important for the substrate binding of TbPRMT6.
Vibrational and thermal study of l-methionine nitrate polycrystals

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Victor, F.M.S.; Ribeiro, L.H.L.; Facanha Filho, P.F.; Santos, C.A.S.; Soares, R.A.; Abreu, D.C.; Sousa, J.C.F.; Carvalho, J.O.; Santos, A.O. dos [Universidade Federal do Maranhao (UFMA), MA (Brazil)

2016-07-01

Full text: Intensified in studies of nonlinear optical materials has been observed over the past two decades for its wide application in telecommunications, optical modulation and optical signal processing. The goal of this work is the thermal and vibrational study of L-methionine nitrate polycrystalline. The polycrystals were obtained by the method of slow evaporation of solvent at ambient temperature of 25 ° C. The X-ray diffraction was performed to confirm the structure of the material, which has monoclinic structure (space group P21) with four molecules per unit cell structure. Refinement by Rietveld method has been optimized and good quality parameters Rwp = 7.97% , Rp = 5.74 and S = 1.92%. The thermal stability of the material was verified from Thermogravimetric analysis (TGA), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). The measures showed a possible phase transition event at about 107°C before the melting point of the material, which took place at about 127°C. Thermogravimetric analysis showed two mass loss events of 61.5% and 30.4%. The vibrational modes of the L-methionine nitrate molecule were identified by Raman spectroscopy in the spectral range between 35cm-1 and 3500 cm-1, the scattering measurements were made from room temperature up to the melting temperature of the material (140 ° C ) in which the disappearance of bands was found in the region of normal modes at 130 ° C, thus demonstrating a irreversible structural phase transition, because the spectrum obtained after returning the sample to ambient temperature is typical of amorphous material. (author)
Methionine kinetics and balance at the 1985 FAO/WHO/UNU intake requirement in adult men studied with L-[2H3-methyl-1-13C]methionine as a tracer

International Nuclear Information System (INIS)

Young, V.R.; Wagner, D.A.; Burini, R.; Storch, K.J.

1991-01-01

The upper range of the requirement for methionine plus cystine in healthy adults was proposed in 1985 by FAO/WHO/UNU to be 13 mg.kg body wt-1.d-1. To explore the validity of this estimate, five healthy, young adult men were given for 7 d a diet based on an L-amino acid mixture supplying 13 mg methionine.kg-1.d-1 (87 mumol.kg-1.d-1) without cystine. Constant intravenous infusions of L-[2H3-methyl-1-13C]methionine were given on days 5 and 7 while subjects were in the fed and postabsorptive states, respectively. Estimates were made of methionine oxidation, and daily methionine balance was derived from the intake-oxidation data. For the five subjects, methionine balances were -0.9, +0.7, +3.5, -3.1, and -3.8 mg kg-1.d-1, or -6, +5, +23, -21, and -26 mumol.kg-1.d-1. These findings lead to the conclusion that the upper range of the requirement for methionine plus cystine probably exceeds 13 mg.kg-1.d-1 in healthy young adults. The implications of this conclusion for establishing an appropriate amount of sulfur amino acids in an amino acid requirement pattern for adults is discussed
Partitioning of L-methionine in aqueous two-phase systems containing poly(propylene glycol) and sodium phosphate salts

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Salabat, Alireza, E-mail: a-salabat@araku.ac.ir [Chemistry Department, Arak University, P.O. Box 38156-879, Arak (Iran, Islamic Republic of); Sadeghi, Rahmat [Department of Chemistry, University of Kurdistan, Sanandaj, Kurdistan 66135 (Iran, Islamic Republic of); Moghadam, Somayeh Tiani [Chemistry Department, Arak University, P.O. Box 38156-879, Arak (Iran, Islamic Republic of); Jamehbozorg, Bahman [Department of Chemistry, University of Kurdistan, Sanandaj, Kurdistan 66135 (Iran, Islamic Republic of)

2011-10-15

Highlights: > Thermodynamics parameters for partitioning of L-methionine in ATPS. > Investigation of different effects on partition coefficient of the amino acid. > Propose the best condition for L-methionine partitioning. - Abstract: The partitioning behavior of L-methionine has been studied in aqueous two-phase systems of (poly(propylene glycol) + sodium phosphate salts + H{sub 2}O) at different temperatures. The salts used were sodium di-hydrogen phosphate (NaH{sub 2}PO{sub 4}), di-sodium hydrogen phosphate (Na{sub 2}HPO{sub 4}) and tri-sodium phosphate (Na{sub 3}PO{sub 4}). The effects of tie line length, salt type, and temperature on the partition coefficient of this amino acid have been studied. In addition, thermodynamic parameters ({Delta}H{sup o}, {Delta}S{sup o} and {Delta}G{sup o}) as a function of temperature were calculated. The results showed that increasing tie line length led to decreasing of the partition coefficient. We also showed that the partition coefficients of the amino acid in the systems containing Na{sub 3}PO{sub 4} are greater than the other two salts. Moreover, it is verified that increasing temperature led to decreasing the partition coefficient. The experimental partition coefficient data are correlated using a modified virial-type model.
Metabolism of 5-methylthioribose to methionine

International Nuclear Information System (INIS)

Miyazaki, J.H.; Yang, S.F.

1987-01-01

During ethylene biosynthesis, the H 3 CS-group of S-adenosylmethionine is released as 5'-methylthioadenosine, which is recycled to methionine via 5-methylthioribose (MTR). In mungbean hypocotyls and cell-free extracts of avocado, [ 14 C]MTR was converted into labeled methionine via 2-keto-4-methylthiobutyric acid (KMB) and 2-hydroxy-4-methylthiobutyric acid (HMB), as intermediates. Incubation of [ribose-U- 14 C]MTR with avocado extract resulted in the production of [ 14 C]formate, indicating the conversion of MTR to KMB involves a loss of formate, presumably from C-1 of MTR. Tracer studies showed that KMB was converted readily in vivo and in vitro to methionine, while HMB was converted much more slowly. The conversion of KMB to methionine by dialyzed avocado extract requires an amino donor. Among several potential donors examined, L-glutamine was the most efficient. Anaerobiosis inhibited only partially the oxidation of MTR to formate, KMB/HMB, and methionine by avocado extract. The role of O 2 in the conversion of MTR to methionine is discussed
Expression, purification, crystallization and preliminary crystallographic study of isolated modules of the mouse coactivator-associated arginine methyltransferase 1

Energy Technology Data Exchange (ETDEWEB)

Troffer-Charlier, Nathalie; Cura, Vincent; Hassenboehler, Pierre; Moras, Dino; Cavarelli, Jean, E-mail: cava@igbmc.u-strasbg.fr [IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Département de Biologie et Génomique Structurales, 1 Rue Laurent Fries, Illkirch, F-67404 (France); INSERM, U596, Illkirch, F-67400 (France); CNRS, UMR7104, Illkirch, F-67400 (France); Université Louis Pasteur, Faculté des Sciences de la Vie, Strasbourg, F-67000 (France)

2007-04-01

Isolated modules of mouse coactivator-associated arginine methyltransferase 1 encompassing the protein arginine N-methyltransferase catalytic domain have been overexpressed, purified and crystallized. X-ray diffraction data have been collected and have enabled determination of the structures by multiple isomorphous replacement using anomalous scattering. Coactivator-associated arginine methyltransferase 1 (CARM1) plays a crucial role in gene expression as a coactivator of several nuclear hormone receptors and also of non-nuclear receptor systems. Its recruitment by the transcriptional machinery induces protein methylation, leading to chromatin remodelling and gene activation. CARM1{sub 28–507} and two structural states of CARM1{sub 140–480} were expressed, purified and crystallized. Crystals of CARM1{sub 28–507} belong to space group P6{sub 2}22, with unit-cell parameters a = b = 136.0, c = 125.3 Å; they diffract to beyond 2.5 Å resolution using synchrotron radiation and contain one monomer in the asymmetric unit. The structure of CARM1{sub 28–507} was solved by multiple isomorphous replacement and anomalous scattering methods. Crystals of apo CARM1{sub 140–480} belong to space group I222, with unit-cell parameters a = 74.6, b = 99.0, c = 207.4 Å; they diffract to beyond 2.7 Å resolution and contain two monomers in the asymmetric unit. Crystals of CARM1{sub 140–480} in complex with S-adenosyl-l-homocysteine belong to space P2{sub 1}2{sub 1}2, with unit-cell parameters a = 74.6, b = 98.65, c = 206.08 Å; they diffract to beyond 2.6 Å resolution and contain four monomers in the asymmetric unit. The structures of apo and holo CARM1{sub 140–480} were solved by molecular-replacement techniques from the structure of CARM1{sub 28–507}.
Mutant form C115H of Clostridium sporogenes methionine γ-lyase efficiently cleaves S-Alk(en)yl-l-cysteine sulfoxides to antibacterial thiosulfinates.

Science.gov (United States)

Kulikova, Vitalia V; Anufrieva, Natalya V; Revtovich, Svetlana V; Chernov, Alexander S; Telegin, Georgii B; Morozova, Elena A; Demidkina, Tatyana V

2016-10-01

Pyridoxal 5'-phosphate-dependent methionine γ-lyase (MGL) catalyzes the β-elimination reaction of S-alk(en)yl-l-cysteine sulfoxides to thiosulfinates, which possess antimicrobial activity. Partial inactivation of the enzyme in the course of the reaction occurs due to oxidation of active site cysteine 115 conserved in bacterial MGLs. In this work, the C115H mutant form of Clostridium sporogenes MGL was prepared and the steady-state kinetic parameters of the enzyme were determined. The substitution results in an increase in the catalytic efficiency of the mutant form towards S-substituted l-cysteine sulfoxides compared to the wild type enzyme. We used a sulfoxide/enzyme system to generate antibacterial activity in situ. Two-component systems composed of the mutant enzyme and three S-substituted l-cysteine sulfoxides were demonstrated to be effective against Gram-positive and Gram-negative bacteria and three clinical isolates from mice. © 2016 IUBMB Life, 68(10):830-835, 2016. © 2016 International Union of Biochemistry and Molecular Biology.
Individual Variations in Inorganic Arsenic Metabolism Associated with AS3MT Genetic Polymorphisms

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Haruo Takeshita

2011-04-01

Full Text Available Individual variations in inorganic arsenic metabolism may influence the toxic effects. Arsenic (+3 oxidation state methyltransferase (AS3MT that can catalyze the transfer of a methyl group from S-adenosyl-L-methionine (AdoMet to trivalent arsenical, may play a role in arsenic metabolism in humans. Since the genetic polymorphisms of AS3MT gene may be associated with the susceptibility to inorganic arsenic toxicity, relationships of several single nucleotide polymorphisms (SNPs in AS3MT with inorganic arsenic metabolism have been investigated. Here, we summarize our recent findings and other previous studies on the inorganic arsenic metabolism and AS3MT genetic polymorphisms in humans. Results of genotype dependent differences in arsenic metabolism for most of SNPs in AS3MT were Inconsistent throughout the studies. Nevertheless, two SNPs, AS3MT 12390 (rs3740393 and 14458 (rs11191439 were consistently related to arsenic methylation regardless of the populations examined for the analysis. Thus, these SNPs may be useful indicators to predict the arsenic metabolism via methylation pathways.
The chlamydial functional homolog of KsgA confers kasugamycin sensitivity to Chlamydia trachomatis and impacts bacterial fitness

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Maurelli Anthony T

2009-12-01

Full Text Available Abstract Background rRNA adenine dimethyltransferases, represented by the Escherichia coli KsgA protein, are highly conserved phylogenetically and are generally not essential for growth. They are responsible for the post-transcriptional transfer of two methyl groups to two universally conserved adenosines located near the 3'end of the small subunit rRNA and participate in ribosome maturation. All sequenced genomes of Chlamydia reveal a ksgA homolog in each species, including C. trachomatis. Yet absence of a S-adenosyl-methionine synthetase in Chlamydia, the conserved enzyme involved in the synthesis of the methyl donor S-adenosyl-L-methionine, raises a doubt concerning the activity of the KsgA homolog in these organisms. Results Lack of the dimethylated adenosines following ksgA inactivation confers resistance to kasugamycin (KSM in E. coli. Expression of the C. trachomatis L2 KsgA ortholog restored KSM sensitivity to the E. coli ksgA mutant, suggesting that the chlamydial KsgA homolog has specific rRNA dimethylase activity. C. trachomatis growth was sensitive to KSM and we were able to isolate a KSM resistant mutant of C. trachomatis containing a frameshift mutation in ksgA, which led to the formation of a shorter protein with no activity. Growth of the C. trachomatis ksgA mutant was negatively affected in cell culture highlighting the importance of the methylase in the development of these obligate intracellular and as yet genetically intractable pathogens. Conclusion The presence of a functional rRNA dimethylase enzyme belonging to the KsgA family in Chlamydia presents an excellent chemotherapeutic target with real potential. It also confirms the existence of S-adenosyl-methionine - dependent methylation reactions in Chlamydia raising the question of how these organisms acquire this cofactor.
S-adenosyl methionine prevents ASD like behaviors triggered by early postnatal valproic acid exposure in very young mice.

Science.gov (United States)

Ornoy, Asher; Weinstein-Fudim, Liza; Tfilin, Matanel; Ergaz, Zivanit; Yanai, Joseph; Szyf, Moshe; Turgeman, Gadi

2018-01-16

A common animal model of ASD is the one induced by valproic acid (VPA), inducing epigenetic changes and oxidative stress. We studied the possible preventive effect of the methyl donor for epigenetic enzymatic reactions, S-adenosine methionine (SAM), on ASD like behavioral changes and on redox potential in the brain and liver in this model. ICR albino mice were injected on postnatal day 4 with one dose of 300 mg/kg of VPA, with normal saline (controls) or with VPA and SAM that was given orally for 3 days at the dose of 30 mg/kg body weight. From day 50, we carried out neurobehavioral tests and assessment of the antioxidant status of the prefrontal cerebral cortex, liver assessing SOD and CAT activity, lipid peroxidation and the expression of antioxidant genes. Mice injected with VPA exhibited neurobehavioral deficits typical of ASD that were more prominent in males. Changes in the activity of SOD and CAT increased lipid peroxidation and changes in the expression of antioxidant genes were observed in the prefrontal cortex of VPA treated mice, more prominent in females, while ASD like behavior was more prominent in males. There were no changes in the redox potential of the liver. The co-administration of VPA and SAM alleviated most ASD like neurobehavioral symptoms and normalized the redox potential in the prefrontal cortex. Early postnatal VPA administration induces ASD like behavior that is more severe in males, while the redox status changes are more severe in females; SAM corrects both. VPA-induced ASD seems to result from epigenetic changes, while the redox status changes may be secondary. Copyright © 2018. Published by Elsevier Inc.
Synthesis of L-[35S] homocysteine thiolactone hydrochloride

International Nuclear Information System (INIS)

Hamacher, K.

1989-01-01

L-[ 35 S]Homocysteine thiolactone has been synthesized by demethylation of L-[ 35 S]Methionine with sodium in liquid ammonia and subsequent lactonisation in acid solution. The radiochemical yield of the carrier added synthesis was in the range of 45 to 50% with a radiochemical purity higher than 96%. (author)
Radiation stability of methionine-35S and selenomethionine-75Se

International Nuclear Information System (INIS)

Galateanu, I.; Lungu, V.V.; Viorel, D.

1976-01-01

The radiation stability of methionine- 35 S and selenomethionine 75 Se was investigated using the methods of thin-layer chromatography, gas chromatography and ESR. Radiation decomposition of methionine- 35 S mainly consists in an oxidation process and in the release of volatile products. The ESR-spectra of irradiated DL-methionine indicated a strong localization of the unpaired electrons on sulfur atoms. Radiation damage to selenomethionine- 75 Se as a function of radiation dose proved an increased stability of this compound and its radiation decomposition consists in the formation of oxidized products and by direct rupture of the selenium bounds accompanied by the formation of volatile compounds like CH 3 SEH and SeH 2 . The self-radiolysis of the aqueous solution of selenomethionine- 75 Se during its storage in air leads, however, to a lower decomposition rate which consists in the release of inorganic selenium and in an oxidation process. (author)
Methionine metabolism and ethylene formation in etiolated pea stem sections

International Nuclear Information System (INIS)

Schilling, N.; Kende, H.

1979-01-01

Stem sections of etiolated pea seedlings (Pisum sativum L. cv. Alaska) were incubated overnight on tracer amounts of L-[U- 14 C]methionine and, on the following morning, on 0.1 millimolar indoleacetic acid to induce ethylene formation. Following the overnight incubation, over 70% of the radioactivity in the soluble fraction was shown to be associated with S-methylmethionine (SMM). The specific radioactivity of the ethylene evolved closely paralleled that of carbon atoms 3 and 4 of methionine extracted from the tissue and was always higher than that determined for carbon atoms 3 and 4 of extracted SMM. Overnight incubation of pea stem sections on 1 millimolar methionine enhanced indoleacetic acid-induced ethylene formation by 5 to 10%. Under the same conditions, 1 millimolar homocysteine thiolactone increased ethylene synthesis by 20 to 25%, while SMM within a concentration range of 0.1 to 10 millimolar did not influence ethylene production. When unlabeled methionine or homocysteine thiolactone was applied to stem sections which had been incubated overnight in L-[U- 14 C]methionine, the specific radioactivity of the ethylene evolved was considerably lowered. Application of unlabeled SMM reduced the specific radioactivity of ethylene only slightly
Stereospecific enzymatic transformation of alpha-ketoglutarate to (2S,3R)-3-methyl glutamate during acidic lipopeptide biosynthesis.

Science.gov (United States)

Mahlert, Christoph; Kopp, Florian; Thirlway, Jenny; Micklefield, Jason; Marahiel, Mohamed A

2007-10-03

The acidic lipopeptides, including the calcium-dependent antibiotics (CDA), daptomycin, and A54145, are important macrocyclic peptide natural products produced by Streptomyces species. All three compounds contain a 3-methyl glutamate (3-MeGlu) as the penultimate C-terminal residue, which is important for bioactivity. Here, biochemical in vitro reconstitution of the 3-MeGlu biosynthetic pathway is presented, using exclusively enzymes from the CDA producer Streptomyces coelicolor. It is shown that the predicted 3-MeGlu methyltransferase GlmT and its homologues DptI from the daptomycin producer Streptomyces roseosporus and LptI from the A54145 producer Streptomyces fradiae do not methylate free glutamic acid, PCP-bound glutamate, or Glu-containing CDA in vitro. Instead, GlmT, DptI, and LptI are S-adenosyl methionine (SAM)-dependent alpha-ketoglutarate methyltransferases that catalyze the stereospecific methylation of alpha-ketoglutarate (alphaKG) leading to (3R)-3-methyl-2-oxoglutarate. Subsequent enzyme screening identified the branched chain amino acid transaminase IlvE (SCO5523) as an efficient catalyst for the transformation of (3R)-3-methyl-2-oxoglutarate into (2S,3R)-3-MeGlu. Comparison of reversed-phase HPLC retention time of dabsylated 3-MeGlu generated by the coupled enzymatic reaction with dabsylated synthetic standards confirmed complete stereocontrol during enzymatic catalysis. This stereospecific two-step conversion of alphaKG to (2S,3R)-3-MeGlu completes our understanding of the biosynthesis and incorporation of beta-methylated amino acids into the nonribosomal lipopeptides. Finally, understanding this pathway may provide new possibilities for the production of modified peptides in engineered microbes.

Role of the transsulfuration pathway and of gamma-cystathionase activity in the formation of cysteine and sulfate from methionine in rat hepatocytes

International Nuclear Information System (INIS)

Rao, A.M.; Drake, M.R.; Stipanuk, M.H.

1990-01-01

To assess the extent to which low hepatic gamma-cystathionase levels affect methionine flux to cysteine in hepatocytes, the effect of inhibition of gamma-cystathionase activity with propargylglycine on the metabolism of L-[ 35 S]methionine was determined in studies with freshly isolated rat hepatocytes. gamma-Cystathionase activity was inhibited 25%, 42%, 63% and 76% (maximal inhibition) by treatment with 2.5 mumol/L, 0.01 mmol/L, 0.02 mmol/L and 2 mmol/l propargylglycine, respectively. Inhibition of gamma-cystathionase activity with up to 0.02 mmol/L propargylglycine had no statistically significant effect on [ 35 S]glutathione, [ 35 S]sulfate or [ 35 S]cysteine formation from [ 35 S]methionine. However, treatment of cells with 2 mmol/L propargylglycine markedly inhibited the metabolism of [ 35 S]methionine to [ 35 S]glutathione by 93%, to [ 35 S]sulfate by 88% and to [ 35 S]cysteine by 89%; [ 35 S]cystathionine accumulation in these incubation systems was 60 times control. Hepatic gamma-cystathionase activity in premature infants has been reported to be about 23% of mature levels; this level of gamma-cystathionase activity may limit cysteine synthesis by the methionine transsulfuration pathway. No evidence for cysteine synthesis from serine and sulfide, which can be catalyzed by cystathionine beta-synthase, or for methionine metabolism by an S-adenosylmethionine-independent pathway was obtained
Detecting 16S rRNA Methyltransferases in Enterobacteriaceae by Use of Arbekacin.

Science.gov (United States)

McGann, Patrick; Chahine, Sarah; Okafor, Darius; Ong, Ana C; Maybank, Rosslyn; Kwak, Yoon I; Wilson, Kerry; Zapor, Michael; Lesho, Emil; Hinkle, Mary

2016-01-01

16S rRNA methyltransferases confer resistance to most aminoglycosides, but discriminating their activity from that of aminoglycoside-modifying enzymes (AMEs) is challenging using phenotypic methods. We demonstrate that arbekacin, an aminoglycoside refractory to most AMEs, can rapidly detect 16S methyltransferase activity in Enterobacteriaceae with high specificity using the standard disk susceptibility test. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
DNA (cytosine-5-methyltransferase 3B (DNMT 3B polymorphism and risk of Down syndrome offspring

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Cláudia Melo de Moura

2018-01-01

Full Text Available Down syndrome (DS is the most common form of human genetic mental retardation. Several polymorphisms in genes coding folic acid cycle enzymes have been associated to the risk of bearing a DS child; however, the results are controversial. S-adenosyl-l-methionine (SAM is an important intermediate of folic acid pathway and acts as methyl donor and substrate for DNA (cytosine-5-methyltransferase 3B (DNMT3B – EC 2.1.1.37 de novo methylation processes during embryogenesis. Recent studies suggest that a functional polymorphism of DNMT 3B in maternal genotype may be associated with a decreased risk of having a DS child. We herein investigate the association of this polymorphism with the occurrence of DS in a Brazilian population. We have genotyped 111 mothers of DS infants (MDS and 212 control mothers (CM through PCR-RFLP. The observed genotypic frequencies were CC = 0.22; CT = 0.49 and TT = 0.29 in CM, and CC = 0.30; CT = 0.52 and TT = 0.18 in MDS. Allelic frequencies were C = 0.47 and T = 0.53 in CM and C = 0.56 and T = 0.44 in MDS. No deviation of HWE was observed, and both DNMT 3B rs2424913 genotype (χ2 = 4.53; DF = 1; P = 0.03 and allelic (χ2 = 4.90; DF = 1; P = 0.03 frequencies show significant differences between MDS and CM. The presence of the mutant DNMT 3B T allele decreases 30% the risk of bearing a DS child (OR = 0.69; 95% CI: 0.50–0.96; P = 0.03, and the risk is diminished up to 45% in association with the homozygous genotype (OR = 0.54; 95% CI: 0.31–0.96; P = 0.04. Our results suggest that women harboring the single nucleotide polymorphism DNMT 3B rs2424913 have a decreased risk of a DS pregnancy, and further studies are necessary to confirm this protective effect.
Cadmium toxicity induced contrasting patterns of concentrations of free sarcosine, specific amino acids and selected microelements in two Noccaea species

Czech Academy of Sciences Publication Activity Database

Zemanová, Veronika; Pavlík, Milan; Pavlíková, D.

2017-01-01

Roč. 12, č. 5 (2017), č. článku e0177963. E-ISSN 1932-6203 Institutional support: RVO:61389030 Keywords : ADENOSYL-L-METHIONINE * ABIOTIC STRESS * GLYCINE BETAINE Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.806, year: 2016
Biological activity of antitumoural MGBG: the structural variable.

Science.gov (United States)

Marques, M P M; Gil, F P S C; Calheiros, R; Battaglia, V; Brunati, A M; Agostinelli, E; Toninello, A

2008-05-01

The present study aims at determining the structure-activity relationships (SAR's) ruling the biological function of MGBG (methylglyoxal bis(guanylhydrazone)), a competitive inhibitor of S-adenosyl-L-methionine decarboxylase displaying anticancer activity, involved in the biosynthesis of the naturally occurring polyamines spermidine and spermine. In order to properly understand its biochemical activity, MGBG's structural preferences at physiological conditions were ascertained, by quantum mechanical (DFT) calculations.
Methionine salvage pathway in relation to ethylene biosynthesis

International Nuclear Information System (INIS)

Miyazaki, J.H.

1987-01-01

The recycling of methionine during ethylene biosynthesis (the methionine cycle) was studied. During ethylene biosynthesis, the H 3 CS-group of S-adenosylmethionine (SAM) is released at 5'-methylthioadenosine (MTA), which is recycled to methionine via 5'-methylthioribose (MTS). In mungbean hypocotyls and cell-free extracts of avocado fruit, [ 14 C]MTR was converted to labeled methionine via 2-keto-4-methylthiobutyric acid (KMB) and 2-hydroxy-4-methylthiobutyric acid (HMB) as intermediates. Radioactive tracer studies showed that KMB was converted readily in vivo and in vitro to methionine, while HMB was converted much more slowly. The conversion of KMB to methionine by dialyzed avocado extract required an amino group donor. Among several potential donors tested, L-glutamine was the most efficient. Incubation of [ribose-U- 14 C]MTR with avocado extract resulted in the production of [ 14 C]formate, with little evolution of other 14 C-labeled one-carbon compounds, indicating that the conversion of MTR to KMB involves a loss of formate, presumably from C-1 of MTR
L-11C-methionine remote controlled synthetic system

International Nuclear Information System (INIS)

Tomiyoshi, Katsumi; Watanabe, Naoyuki; Tateno, Madoka; Oriuchi, Noboru; Hirano, Tsuneo; Inoue, Tomio; Endo, Keigo

1992-01-01

L- 11 C-methionine have been used clinically in studies of brain tumors in combination with 18 F-fluorodeoxyglucose ( 18 FDG). In respect with synthesizing radiopharmaceuticals, high radioactivity and constant radiochemical yield have to be obtained in routine bases. Therefore automatic synthesis apparatus is inevitable to carry out following points. 1) Radiation Exposure Protection: Half life of 11 C having 20 minutes, starting high radioactivity give a lot of exposure dose to hands and body. 2) Constant radiochemical yield: Amount of radiochemical yield is likely to be varied in manual synthesis which could lead little activity or cancellation to inject. (author)
Synergistic Effect of L-Methionine and KI on Copper Corrosion Inhibition in HNO3 (1M

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Amel SEDIK

2014-05-01

Full Text Available L-Methionine (L-Met efficiency as a non-toxic corrosion inhibitor for copper in 1M HNO3 has been studied by using electrochemical impedance spectroscopy (EIS and potentiodynamic polarization. Copper corrosion rate significant decrease was observed in the presence of L-Met at 10-4M. The Obtained Results from potentiodynamic polarization and impedance measurements are in good agreement. L-Methionine adsorption on copper surface follows Langmuir isotherm. L-Met free energy adsorption on copper (-30 KJ mol-1 reveals an inhibition strong physical adsorption on copper surface. In order to evaluate the L-Met effect, L-Met and iodide ion’synergistic effect was used to prevent copper corrosion in nitric acid. It was found that inhibitor efficiency (IE reached 98.27 % in 1M solution containing 10-4M L-Met and 10- 3 M KI. The synergistic effect was attributed to iodide ions adsorption on copper surface, which facilitated the L-Met adsorption and an inhibitive film formation.
Metal active site elasticity linked to activation of homocysteine in methionine synthases

Energy Technology Data Exchange (ETDEWEB)

Koutmos, Markos; Pejchal, Robert; Bomer, Theresa M.; Matthews, Rowena G.; Smith, Janet L.; Ludwig, Martha L. (Michigan)

2008-04-02

Enzymes possessing catalytic zinc centers perform a variety of fundamental processes in nature, including methyl transfer to thiols. Cobalamin-independent (MetE) and cobalamin-dependent (MetH) methionine synthases are two such enzyme families. Although they perform the same net reaction, transfer of a methyl group from methyltetrahydrofolate to homocysteine (Hcy) to form methionine, they display markedly different catalytic strategies, modular organization, and active site zinc centers. Here we report crystal structures of zinc-replete MetE and MetH, both in the presence and absence of Hcy. Structural investigation of the catalytic zinc sites of these two methyltransferases reveals an unexpected inversion of zinc geometry upon binding of Hcy and displacement of an endogenous ligand in both enzymes. In both cases a significant movement of the zinc relative to the protein scaffold accompanies inversion. These structures provide new information on the activation of thiols by zinc-containing enzymes and have led us to propose a paradigm for the mechanism of action of the catalytic zinc sites in these and related methyltransferases. Specifically, zinc is mobile in the active sites of MetE and MetH, and its dynamic nature helps facilitate the active site conformational changes necessary for thiol activation and methyl transfer.
Quantitative proteomics reveals the mechanism and consequence of gliotoxin-mediated dysregulation of the methionine cycle in Aspergillus niger.

Science.gov (United States)

Manzanares-Miralles, Lara; Sarikaya-Bayram, Özlem; Smith, Elizabeth B; Dolan, Stephen K; Bayram, Özgür; Jones, Gary W; Doyle, Sean

2016-01-10

Gliotoxin (GT) is a redox-active metabolite, produced by Aspergillus fumigatus, which inhibits the growth of other fungi. Here we demonstrate how Aspergillus niger responds to GT exposure. Quantitative proteomics revealed that GT dysregulated the abundance of 378 proteins including those involved in methionine metabolism and induced de novo abundance of two S-adenosylmethionine (SAM)-dependent methyltransferases. Increased abundance of enzymes S-adenosylhomocysteinase (p=0.0018) required for homocysteine generation from S-adenosylhomocysteine (SAH), and spermidine synthase (p=0.0068), involved in the recycling of Met, was observed. Analysis of Met-related metabolites revealed significant increases in the levels of Met and adenosine, in correlation with proteomic data. Methyltransferase MT-II is responsible for bisthiobis(methylthio)gliotoxin (BmGT) formation, deletion of MT-II abolished BmGT formation and led to increased GT sensitivity in A. niger. Proteomic analysis also revealed that GT exposure also significantly (pniger. Thus, it provides new opportunities to exploit the response of GT-naïve fungi to GT. Copyright © 2015 Elsevier B.V. All rights reserved.
Effects of secretagogues on ATP levels and protein carboxyl methylation in rat brain synaptosomes

International Nuclear Information System (INIS)

Bjorndahl, J.M.; Rutledge, C.O.

1986-01-01

The influence of various substances which are known to alter free intracellular calcium concentrations on protein carboxyl methyltransferase (PCM) activity was investigated in rat brain synaptosomes. The synaptosomes were labeled with L-[ 3 H]methionine and the 3 H-methyl esters of proteins were formed from the methyl donor S-[ 3 H]adenosyl-L-methionine ([ 3 H]AdoMet). The calcium ionophore A23187 and ouabain decreased PCM activity and the decrease produced by A23187 was antagonized by ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid and MnCl 2 . On the other hand, ruthenium red, an inhibitor of calcium uptake, stimulated PCM activity. These data suggest that PCM activity is inversely related to the free cytoplasmic calcium concentration. Veratridine, A23187 and elevated potassium ions decreased the levels of ATP and [ 3 H]AdoMet. The A23187-mediated decrease in ATP levels and the reduced [ 3 H]AdoMet formation was antagonized by ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid and MnCl 2 . Inhibition of metabolic activity of the synaptosomes by NaCN led to: decreased ATP levels; inhibition of [3H]AdoMet formation; and inhibition of PCM activity. These data suggest that the decrease in protein methylation produced by secretagogues is associated with an increase in the concentration of free intracellular calcium which results in a decrease in the metabolically active pool of ATP. This leads to a decreased rate of AdoMet formation, a cosubstrate for PCM and a resultant decrease in PCM activity
Synthesis, characterization of Ag-Au core-shell bimetal nanoparticles and its application for electrocatalytic oxidation/sensing of L-methionine

Energy Technology Data Exchange (ETDEWEB)

Murugavelu, M.; Karthikeyan, B., E-mail: bkarthi_au@yahoo.com

2017-01-01

The Ag-Au core-shell bimetal nanoparticles (BNPs) was prepared using chemical reduction method. The prepared Ag-Au core-shell BNPs were characterized by UV–Visible (UV–Vis) spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) pattern. These results showed the Ag-Au BNPs exhibited core-shell shape. The Ag-Au core-shell BNPs was examined towards electrocatalytic oxidation of L-methionine (L-Met) by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry. According to the results, L-Met is determined with detection limit of 30 μM. Interference studies in biological buffer was also studied. - Highlights: • The Ag-Au core-shell BNPs are synthesized and characterized • Ag-Au core-shell BNPs modified (Ag-Au/GCE) has been examined for L-methionine oxidation/sensing by using electrochemical method. • The Ag-Au/GCE exhibited good performance for the detection of L-methionine.
Activities of methionine-γ-lyase in the acidophilic archaeon “Ferroplasma acidarmanus” strain fer1

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Khan MA

2013-04-01

Full Text Available M A Khan,1 Madeline M López-Muñoz,2 Charles W Kaspar,3 Kai F Hung1 1Department of Biological Sciences, Eastern Illinois University, Charleston, IL, USA; 2Department of Biology, Universidad de Puerto Rico, Mayaguez, Puerto Rico; 3Bacteriology Department, University of Wisconsin, Madison, WI, USA Abstract: Biogeochemical processes on exposed pyrite ores result in extremely high levels of sulfuric acid at these locations. Acidophiles that thrive in these conditions must overcome significant challenges, including an environment with proton concentrations at pH 3 or below. The role of sulfur metabolism in the archaeon “Ferroplasma acidarmanus” strain fer1's ability to thrive in this environment was investigated due to its growth-dependent production of methanethiol, a volatile organic sulfur compound. Two putative sequences for methionine-γ-lyase (EC 4.4.1.11, an enzyme known to carry out α, γ-elimination on L-methionine to produce methanethiol, were identified in fer1. Bioinformatic analyses identified a conserved pyridoxal-5'-phosphate (PLP binding domain and a partially conserved catalytic domain in both putative sequences. Detection of PLP-dependent and L-methionine-dependent production of α-keto compounds and thiol groups in fer1 confirmed the presence of methionine-γ-lyase activity. Further, fer1 lysate was capable of processing related substrates, including D-methionine, L-cysteine, L-cystathionine, and L/D-homocysteine. When the two putative fer1 methionine-γ-lyase gene-coded proteins were expressed in Escherichia coli cells, one sequence demonstrated an ability to carry out α, γ-elimination activity, while the other exhibited γ-replacement activity. These fer1 methionine-γ-lyases also exhibited optimum pH, substrate specificity, and catalytic preferences that are different from methionine-γ-lyases from other organisms. These differences are discussed in the context of molecular phylogeny constructed using a maximum
Association between TPMT*3C and decreased thiopurine S-methyltransferase activity in patients with neuromyelitis optica spectrum disorders in China.

Science.gov (United States)

Gong, Xiaoqing; Mei, Shenghui; Li, Xindi; Li, Xingang; Zhou, Heng; Liu, Yonghong; Zhou, Anna; Yang, Li; Zhao, Zhigang; Zhang, Xinghu

2018-06-01

Thiopurines are effective drugs in treating neuromyelitis optica spectrum disorders and other diseases. Thiopurines' toxicity is mainly imputed to thiopurine S-methyltransferase activity. In Chinese population, the most common and important variation of thiopurine S-methyltransferase is TPMT*3C (rs1142345). This study aims to reveal the association between thiopurine S-methyltransferase activity and genetic polymorphisms of thiopurine S-methyltransferase in patients with neuromyelitis optica spectrum disorders in China. A liquid chromatography tandem mass/mass method was used to evaluate the thiopurine S-methyltransferase activity by using 6-mercapthioprine as the substrate in human erythrocyte haemolysate via 1 h incubation at 37 °C to form its methylated product 6-methylmercaptopurine. The amount of 6-methylmercaptopurine was adjusted by haematocrit and normalized to 8 × 10 8 erythrocytes. The selected polymorphisms of thiopurine S-methyltransferase were identified using MassARRAY system (Sequenom) and multiple SNaPshot technique. In 69 patients with neuromyelitis optica spectrum disorders, thiopurine S-methyltransferase activity was 80.29-154.53 (127.51 ± 16.83) pmol/h/8 × 10 8 erythrocytes. TPMT*3C (rs1142345) was associated with lower thiopurine S-methyltransferase activity (BETA = -25.37, P = 0.011). Other selected variants were not associated with thiopurine S-methyltransferase activity. TPMT*3C affects TPMT activity in Chinese patients with neuromyelitis optica spectrum disorders. Further studies are warranted to confirm the results. TPRs = thiopurines; NMOSD = neuromyelitis optica spectrum disorders; TPMT = thiopurine S-methyltransferase; LC-MS/MS = liquid chromatography tandem mass/mass; 6-MMP = 6-methylmercaptopurine; IS = internal standard; SNP = single nucleotide polymorphism; MAF = minor allele frequency; HWE = Hardy-Weinberg equilibrium; BETA = regression coefficients; UTR-3 = untranslated region 3.
Methionine metabolism after portacaval shunt in the rat

International Nuclear Information System (INIS)

Benjamin, L.E.; Steele, R.D.

1985-01-01

The effect of portacaval shunt (PCS) on methionine metabolism in the rat was investigated. Male Sprague-Dawley rats were subjected to PCS and maintained on an 18% casein diet. Growth curves of operated rats were similar to controls. PCS rats excreted more urinary 35 SO 4 and less [ 35 S]taurine than controls after intraperitoneal injection of 0.3 mmol/100 g [ 35 S]methionine or [ 35 S]cysteine. Total urinary taurine excretion was similar in PCS and control rats after a methionine or cysteine load; however, under basal conditions PCS rats had higher urinary taurine levels than controls, indicating that PCS may cause the taurine pool to be expanded. Hepatic methionine, S-adenosylmethionine, and cysteine pools were significantly decreased in PCS rats, while S-adenosylhomocysteine levels were unchanged. Relative rates of transsulfuration in PCS and control rats were studied by following the decrease in the 3 H-to- 35 S ratio in liver protein after injection of [methyl-3H]methionine and [ 35 S]methionine, and no difference in flux of 35 S from [ 35 S]methionine to [ 35 S]cysteine was found. Similarly, total hepatic activities of methionine adenosyltransferase, cystathionine synthase, and cystathionine gamma-lyase were unchanged in PCS rats. These results indicate that altered methionine metabolism in PCS rats is not explained by changes in conversion of methionine to cysteine via the transsulfuration pathway
Biochemical research elucidating metabolic pathways in Pneumocystis*

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Kaneshiro E.S.

2010-12-01

Full Text Available Advances in sequencing the Pneumocystis carinii genome have helped identify potential metabolic pathways operative in the organism. Also, data from characterizing the biochemical and physiological nature of these organisms now allow elucidation of metabolic pathways as well as pose new challenges and questions that require additional experiments. These experiments are being performed despite the difficulty in doing experiments directly on this pathogen that has yet to be subcultured indefinitely and produce mass numbers of cells in vitro. This article reviews biochemical approaches that have provided insights into several Pneumocystis metabolic pathways. It focuses on 1 S-adenosyl-L-methionine (AdoMet; SAM, which is a ubiquitous participant in numerous cellular reactions; 2 sterols: focusing on oxidosqualene cyclase that forms lanosterol in P. carinii; SAM:sterol C-24 methyltransferase that adds methyl groups at the C-24 position of the sterol side chain; and sterol 14α-demethylase that removes a methyl group at the C-14 position of the sterol nucleus; and 3 synthesis of ubiquinone homologs, which play a pivotal role in mitochondrial inner membrane and other cellular membrane electron transport.
Antileishmanial activity of berenil and methylglyoxal bis (guanylhydrazone) and its correlation with S-adenosylmethionine decarboxylase and polyamines.

Science.gov (United States)

Mukhopadhyay, R; Madhubala, R

1995-01-01

Leishmania donovani S-adenosyl-L-methionine (AdoMet) decarboxylase was found to show a growth related pattern. Methylglyoxal bis (guanylhydrazone) (MGBG) and Berenil inhibited the growth of Leishmania donovani promastigotes (strain UR6) in a dose dependent manner. The concentrations of MGBG and Berenil required for 50% inhibition of rate of growth were 67 and 47 microM, respectively. The growth inhibition of MGBG was partially reversed by spermidine (100 microM) and spermine (100 microM). Berenil inhibition of promastigote growth was partially reversed by 100 microM spermidine whereas 100 microM spermine did not result in any reversal of growth. The reduction in parasitemia in vitro by these inhibitors was accompanied by inhibition of AdoMet decarboxylase activity and spermidine levels.
Parameters of the labeling of mitogen-activated murine lymphocytes by [35S]methionine for two-dimensional gel electrophoresis. I

International Nuclear Information System (INIS)

Kettman, J.R.

1986-01-01

Labeling with [ 35 S]methionine at a high specific activity is essential to the facile preparation of 2-dimensional gel electrophoretograms with the analytical 2-dimensional charge-size separation procedure. Mitogen-activated T and B lymphocytes subjected to low methionine concentrations would not proceed through cell cycle. In the case of activated B lymphocytes, the use of fetal bovine serum, dialyzed to lower endogenous methionine concentrations, prevented B cell growth even in the presence of otherwise satisfactory levels of methionine. High concentrations of [ 35 S]methionine induced B cell death, apparently by radiation damage. Despite these problems, good radioautograms and radiofluorograms of 2D electrophoretograms could be prepared by labeling activated B or T cells in bulk with high specific activity [ 35 S]methionine. (Auth.)
Methylation of nucleolar RNA in HeLa cells studied by autoradiography

International Nuclear Information System (INIS)

Cervera, J.; Martinez, A.; Renau-Piqueras, J.

1984-01-01

Methylation of nucleolar RNA was studied by autoradiography in HeLa cells using L-[methyl- 3 H]methionine and S-adenosyl-L-[methyl- 3 H]methionine as radioactive precursors. Pulse-labeling experiments show that nucleolar RNA methylation occurs on the newly synthesized RNA at the nucleolar fibrillar RNP component and mostly on the fibrillar ring of fibrillar centers, where pre-rRNA is being synthesized. Pulse-chase experiments show a shift of silver grains from the nucleolar fibrillar RNP component to the nucleolar granular component first and then to the cytoplasm. Labeling of nucleolar RNA via specific methylation permits the study of intranucleolar processing of pre-rRNA and confirms the sequence of labeling of the two nucleolar RNP components observed with radioactive uridine
Local cerebral metabolic rate of 11C-L-Methionine in early stages of dementia, schizophrenia, Parkinson's disease

International Nuclear Information System (INIS)

Bustany, P.; Henry, J.F.; de Rotrou, J.; Signoret, J.L.; Ziegler, M.; Zarifian, E.; Soussaline, F.; Comar, D.

1983-06-01

A dynamic three-compartment model of methionine metabolism in brain was applied in human patients using 11 C-L-Methionine and positron emission tomography (P.E.T). Psychometric evaluations of demented patients were correlated with a significant diminution of protein synthesis in the frontal area. This diminution was lower in ebephrenic patients (-17%) but was consistent with the results obtained with 18 F glucose. No significant abnormality was detected in patients with Parkinson disease

Cognitive dysfunction in depression - pathophysiology and novel targets

DEFF Research Database (Denmark)

Carvalho, Andre F; Miskowiak, Kamilla Woznica; Hyphantis, Thomas N

2014-01-01

, inflammation (e.g., enhanced production of pro-inflammatory cytokines), mitochondrial dysfunction, increased apoptosis as well as a diminished neurotrophic support. Several promising neurotherapeutic targets were identified such as minocycline, statins, anti-inflammatory compounds, N-acetylcysteine, omega-3...... poliunsaturated fatty acids, erythropoietin, thiazolidinediones, glucagon-like peptide-1 analogues, S-adenosyl-l-methionine (SAMe), cocoa flavonols, creatine monohydrate and lithium. Erythropoietin and SAMe had pro-cognitive effects in randomized controlled trials (RCT) involving MDD patients. Despite having...
Cloning and expressing a highly functional and substrate specific farnesoic acid o-methyltransferase from the Asian citrus psyllid (Diaphorina citri Kuwayama).

Science.gov (United States)

Van Ekert, Evelien; Shatters, Robert G; Rougé, Pierre; Powell, Charles A; Smagghe, Guy; Borovsky, Dov

2015-01-01

The Asian citrus psyllid, Diaphorina citri, transmits a phloem-limited bacterium, Candidatus 'Liberibacter' asiaticus that causes citrus greening disease. Because juvenile hormone (JH) plays an important role in adult and nymphal development, we studied the final steps in JH biosynthesis in D. citri. A putative JH acid methyltransferase ortholog gene (jmtD) and its cognate cDNA were identified by searching D. citri genome database. Expression analysis shows expression in all life stages. In adults, it is expressed in the head-thorax, (containing the corpora allata), and the abdomen (containing ovaries and male accessory glands). A 3D protein model identified the catalytic groove with catalytically active amino acids and the S-adenosyl methionine (SAM)-binding loop. The cDNA was expressed in Escherichia coli cells and the purified enzyme showed high preference for farnesoic acid (FA) and homoFA (kcat of 0.752 × 10(-3) and 0.217 × 10(-3) s(-1), respectively) as compared to JH acid I (JHA I) (cis/trans/cis; 2Z, 6E, 10cis), JHA III (2E, 6E, 10cis), and JHA I (trans/cis/cis; 2E, 2Z, 10cis) (kcat of 0.081 × 10(-3), 0.013 × 10(-3), and 0.003 × 10(-3) s(-1), respectively). This suggests that this ortholog is a DcFA-o-methyl transferase gene (fmtD), not a jmtD, and that JH biosynthesis in D. citri proceeds from FA to JH III through methyl farnesoate (MF). DcFA-o-MT does not require Ca(2+), Mg(2+) or Zn(2+), however, Zn(2+) (1 mM) completely inhibits the enzyme probably by binding H115 at the active groove. This represents the first purified FA-o-MT from Hemiptera with preferred biological activity for FA and not JHA.
Dissecting the Catalytic Mechanism of Betaine-Homocysteine S-Methyltransferase Using Intrinsic Tryptophan Fluorescence and Site-Directed Mutagenesis

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Castro, C.; Gratson, A.A.; Evans, J.C.; Jiracek, J.; Collinsova, M.; Ludwig, M.L.; Garrow, T.A. (ASCR); (UIUC); (Michigan)

2010-03-05

Betaine-homocysteine S-methyltransferase (BHMT) is a zinc-dependent enzyme that catalyzes the transfer of a methyl group from glycine betaine (Bet) to homocysteine (Hcy) to form dimethylglycine (DMG) and methionine (Met). Previous studies in other laboratories have indicated that catalysis proceeds through the formation of a ternary complex, with a transition state mimicked by the inhibitor S-({delta}-carboxybutyl)-l-homocysteine (CBHcy). Using changes in intrinsic tryptophan fluorescence to determine the affinity of human BHMT for substrates, products, or CBHcy, we now demonstrate that the enzyme-substrate complex reaches its transition state through an ordered bi-bi mechanism in which Hcy is the first substrate to bind and Met is the last product released. Hcy, Met, and CBHcy bind to the enzyme to form binary complexes with K{sub d} values of 7.9, 6.9, and 0.28 {micro}M, respectively. Binary complexes with Bet and DMG cannot be detected with fluorescence as a probe, but Bet and DMG bind tightly to BHMT-Hcy to form ternary complexes with K{sub d} values of 1.1 and 0.73 {micro}M, respectively. Mutation of each of the seven tryptophan residues in human BHMT provides evidence that the enzyme undergoes two distinct conformational changes that are reflected in the fluorescence of the enzyme. The first is induced when Hcy binds, and the second, when Bet binds. As predicted by the crystal structure of BHMT, the amino acids Trp44 and Tyr160 are involved in binding Bet, and Glu159 in binding Hcy. Replacing these residues by site-directed mutagenesis significantly reduces the catalytic efficiency (V{sub max}/K{sub m}) of the enzyme. Replacing Tyr77 with Phe abolishes enzyme activity.
l-Methionine and silymarin: A comparison of prophylactic protective capabilities in acetaminophen-induced injuries of the liver, kidney and cerebral cortex.

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Onaolapo, Olakunle J; Adekola, Moses A; Azeez, Taiwo O; Salami, Karimat; Onaolapo, Adejoke Y

2017-01-01

We compared the relative protective abilities of silymarin and l-methionine pre-treatment in acetaminophen overdose injuries of the liver, kidney and cerebral cortex by assessing behaviours, antioxidant status, tissue histological changes and biochemical parameters of hepatic/renal function. Rats were divided into six groups of ten each; animals in five of these groups were pre-treated with oral distilled water, silymarin (25mg/kg) or l-methionine (2.5, 5 and 10mg/kg body weight) for 14days; and then administered intraperitoneal (i.p.) acetaminophen at 800mg/kg/day for 3days. Rats in the sixth group (normal control) received distilled water orally for 14days and then i.p. for 3days. Neurobehavioural tests were conducted 7days after last i.p treatment, and animals sacrificed on the 8th day. Plasma was assayed for biochemical markers of liver/kidney function; while sections of the liver, kidney and cerebral cortex were either homogenised for assay of antioxidant status or processed for histology. Acetaminophen overdose resulted in locomotor retardation, excessive self-grooming, working-memory impairment, anxiety, derangement of liver/kidney biochemistry, antioxidant imbalance, and histological changes in the liver, kidney and cerebral cortex. Administration of silymarin or increasing doses of l-methionine counteracted the behavioural changes, reversed biochemical indices of liver/kidney injury, and improved antioxidant activity. Silymarin and l-methionine also conferred variable degrees of tissue protection, on histology. Either silymarin or l-methionine can protect vulnerable tissues from acetaminophen overdose injury; however, each offers variable protection to different tissues. This study highlights an obstacle to seeking the 'ideal' protective agent against acetaminophen overdose. Copyright © 2016 Elsevier Masson SAS. All rights reserved.
Three's company: co-crystallization of a self-assembled S(4) metallacyclophane with two diastereomeric metallacycle intermediates.

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Lindquist, Nathan R; Carter, Timothy G; Cangelosi, Virginia M; Zakharov, Lev N; Johnson, Darren W

2010-05-28

Three discrete supramolecular self-assembled arsenic(iii) complexes including an unusual S(4)-symmetric tetranuclear [As(4)L(2)Cl(4)] metallacyclophane and two diastereomeric cis/trans-[As(2)LCl(2)] metallacycle intermediates co-crystallize within a single crystal lattice.
The Effects of Subchronic Methionine Overload Administered Alone or Simultaneously with L-cysteine or N-acetyl-L-cysteine on Body Weight, Homocysteine Levels and Biochemical Parameters in the Blood of Male Wistar Rats

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Micovic Zarko

2016-09-01

Full Text Available Hyperhomocysteinemia (HHC, both basal and after methionine load, may occur due to genetic disorders or deficiencies of nutrients that affect the remethylation or trans-sulphuration pathways during methionine metabolism. HHC is involved in the pathogenesis of many illnesses as a result of its prooxidative effect and its impairment of antioxidative protection. The aim was to examine the effects of subchronic methionine overload on the body weight and standard biochemical parameters in rat serum and to examine whether simultaneous subchronic intraperotoneal administration of methionine alone or together with L-cysteine or N-acetyl-cysteine resulted in a change in the body weight and biochemical parameters in the rat serum. The research was conducted during a three-week period (male Wistar albino rats, n=36, body weight of approximately 160 g, age of 15-20 days, and the animals were divided into a control group and three experimental groups of 8-10 animals each: a control group (0.9% sodium chloride 0.1-0.2 ml/day; b methionine (0.8 mmol/kg/bw/day (MET group; c methionine (0.8 mmol/kg/bw/day + L-cysteine (7 mg/kg/bw/day (L-cys+MET group; and d methionine (0.8 mmol/kg/bw/day + N-acetyl-L-cysteine (50 mg/kg/bw/day (NAC+MET group. In addition to the body weight monitoring, the levels of total homocysteine and the standard biochemical parameters in blood samples (plasma or serum were determined. The results indicated that monitoring the homocysteine levels and standard biochemical parameters in blood could be used for analysis and could provide an excellent guideline for distinguishing between toxic and non-toxic doses of methionine intake, which may be meaningful for clinical applications.
Methyltransferase That Modifies Guanine 966 of the 16 S rRNA: FUNCTIONAL IDENTIFICATION AND TERTIARY STRUCTURE*

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Lesnyak, Dmitry V.; Osipiuk, Jerzy; Skarina, Tatiana; Sergiev, Petr V.; Bogdanov, Alexey A.; Edwards, Aled; Savchenko, Alexei; Joachimiak, Andrzej; Dontsova, Olga A.

2010-01-01

N2-Methylguanine 966 is located in the loop of Escherichia coli 16 S rRNA helix 31, forming a part of the P-site tRNA-binding pocket. We found yhhF to be a gene encoding for m2G966 specific 16 S rRNA methyltransferase. Disruption of the yhhF gene by kanamycin resistance marker leads to a loss of modification at G966. The modification could be rescued by expression of recombinant protein from the plasmid carrying the yhhF gene. Moreover, purified m2G966 methyltransferase, in the presence of S-adenosylomethionine (AdoMet), is able to methylate 30 S ribosomal subunits that were purified from yhhF knock-out strain in vitro. The methylation is specific for G966 base of the 16 S rRNA. The m2G966 methyltransferase was crystallized, and its structure has been determined and refined to 2.05 Å. The structure closely resembles RsmC rRNA methyltransferase, specific for m2G1207 of the 16 S rRNA. Structural comparisons and analysis of the enzyme active site suggest modes for binding AdoMet and rRNA to m2G966 methyltransferase. Based on the experimental data and current nomenclature the protein expressed from the yhhF gene was renamed to RsmD. A model for interaction of RsmD with ribosome has been proposed. PMID:17189261
Methyltransferase that modifies guanine 966 of the 16 S rRNA: functional identification and tertiary structure.

Science.gov (United States)

Lesnyak, Dmitry V; Osipiuk, Jerzy; Skarina, Tatiana; Sergiev, Petr V; Bogdanov, Alexey A; Edwards, Aled; Savchenko, Alexei; Joachimiak, Andrzej; Dontsova, Olga A

2007-02-23

N(2)-Methylguanine 966 is located in the loop of Escherichia coli 16 S rRNA helix 31, forming a part of the P-site tRNA-binding pocket. We found yhhF to be a gene encoding for m(2)G966 specific 16 S rRNA methyltransferase. Disruption of the yhhF gene by kanamycin resistance marker leads to a loss of modification at G966. The modification could be rescued by expression of recombinant protein from the plasmid carrying the yhhF gene. Moreover, purified m(2)G966 methyltransferase, in the presence of S-adenosylomethionine (AdoMet), is able to methylate 30 S ribosomal subunits that were purified from yhhF knock-out strain in vitro. The methylation is specific for G966 base of the 16 S rRNA. The m(2)G966 methyltransferase was crystallized, and its structure has been determined and refined to 2.05A(.) The structure closely resembles RsmC rRNA methyltransferase, specific for m(2)G1207 of the 16 S rRNA. Structural comparisons and analysis of the enzyme active site suggest modes for binding AdoMet and rRNA to m(2)G966 methyltransferase. Based on the experimental data and current nomenclature the protein expressed from the yhhF gene was renamed to RsmD. A model for interaction of RsmD with ribosome has been proposed.
Analysis of the kinetic mechanism of recombinant human isoprenylcysteine carboxylmethyltransferase (Icmt

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Baron Rudi A

2004-12-01

Full Text Available Abstract Background Isoprenylcysteine carboxyl methyltransferase (Icmt is the third of three enzymes that posttranslationally modify proteins that contain C-terminal CaaX motifs. The processing of CaaX proteins through this so-called prenylation pathway via a route initiated by addition of an isoprenoid lipid is required for both membrane targeting and function of the proteins. The involvement of many CaaX proteins such as Ras GTPases in oncogenesis and other aberrant proliferative disorders has led to the targeting of the enzymes involved in their processing for therapeutic development, necessitating a detailed understanding of the mechanisms of the enzymes. Results In this study, we have investigated the kinetic mechanism of recombinant human Icmt. In the reaction catalyzed by Icmt, S-adenosyl-L-methionine (AdoMet provides the methyl group that is transferred to the second substrate, the C-terminal isoprenylated cysteine residue of a CaaX protein, thereby generating a C-terminal prenylcysteine methyl ester on the protein. To facilitate the kinetic analysis of Icmt, we synthesized a new small molecule substrate of the enzyme, biotin-S-farnesyl-L-cysteine (BFC. Initial kinetic analysis of Icmt suggested a sequential mechanism for the enzyme that was further analyzed using a dead end competitive inhibitor, S-farnesylthioacetic acid (FTA. Inhibition by FTA was competitive with respect to BFC and uncompetitive with respect to AdoMet, indicating an ordered mechanism with SAM binding first. To investigate the order of product dissociation, product inhibition studies were undertaken with S-adenosyl-L-homocysteine (AdoHcy and the N-acetyl-S-farnesyl-L-cysteine methylester (AFCME. This analysis indicated that AdoHcy is a competitive inhibitor with respect to AdoMet, while AFCME shows a noncompetitive inhibition with respect to BFC and a mixed-type inhibition with respect to AdoMet. These studies established that AdoHcy is the final product released, and
Increased amounts of D-enantiomer dependent on alkaline concentration in the synthesis of L-[methyl-11C]methionine

International Nuclear Information System (INIS)

Ishiwata, Kiichi; Ido, Tatsuo; Vaalburg, W.

1988-01-01

The presence of D-enantiomer in L-[methyl- 11 C]methionine prepared from [ 11 C]CH 3 I and L-homocysteine thiolactone, was measured by high performance liquid chromatography using a reverse-phase column with an eluent containing L-proline and cupric acetate. The amount of D-enantiomer increased with concentration of NaOH used. The reaction time, 2-10 min, and the reaction temperature, 40 0 -80 0 C, have only minor effect on the formation of D-enantiomer. No significant difference was found for three different lots of L-homocysteine thiolactone. At the highest concentration investigated, 1.0 M NaOH in 50% aqueous acetone, the percentage of D-enantiomer was found to be 7.7%. With 0.025 M NaOH used only 2.1% was measured. When L-[methyl- 11 C]methionine was incubated in 1.0 M NaOH, no conversion of L- into D-enantiomer was observed. (author)
Crystal structures of human 108V and 108M catechol O-methyltransferase

Energy Technology Data Exchange (ETDEWEB)

Rutherford, K.; Le Trong, I.; Stenkamp, R.E.; Parson, W.W. (UWASH)

2008-08-01

Catechol O-methyltransferase (COMT) plays important roles in the metabolism of catecholamine neurotransmitters and catechol estrogens. The development of COMT inhibitors for use in the treatment of Parkinson's disease has been aided by crystallographic structures of the rat enzyme. However, the human and rat proteins have significantly different substrate specificities. Additionally, human COMT contains a common valine-methionine polymorphism at position 108. The methionine protein is less stable than the valine polymorph, resulting in decreased enzyme activity and protein levels in vivo. Here we describe the crystal structures of the 108V and 108M variants of the soluble form of human COMT bound with S-adenosylmethionine (SAM) and a substrate analog, 3,5-dinitrocatechol. The polymorphic residue 108 is located in the {alpha}5-{beta}3 loop, buried in a hydrophobic pocket {approx}16 {angstrom} from the SAM-binding site. The 108V and 108M structures are very similar overall [RMSD of C{sup {alpha}} atoms between two structures (C{sup {alpha}} RMSD) = 0.2 {angstrom}], and the active-site residues are superposable, in accord with the observation that SAM stabilizes 108M COMT. However, the methionine side chain is packed more tightly within the polymorphic site and, consequently, interacts more closely with residues A22 ({alpha}2) and R78 ({alpha}4) than does valine. These interactions of the larger methionine result in a 0.7-{angstrom} displacement in the backbone structure near residue 108, which propagates along {alpha}1 and {alpha}5 toward the SAM-binding site. Although the overall secondary structures of the human and rat proteins are very similar (C{sup {alpha}} RMSD = 0.4 {angstrom}), several nonconserved residues are present in the SAM-(I89M, I91M, C95Y) and catechol- (C173V, R201M, E202K) binding sites. The human protein also contains three additional solvent-exposed cysteine residues (C95, C173, C188) that may contribute to intermolecular disulfide bond
Local cerebral metabolic rate of /sup 11/C-L-Methionine in early stages of dementia, schizophrenia, Parkinson's disease

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Bustany, P; Henry, J F; de Rotrou, J; Signoret, J L; Ziegler, M; Zarifian, E; Soussaline, F; Comar, D

1983-06-01

A dynamic three-compartment model of methionine metabolism in brain was applied in human patients using /sup 11/C-L-methionine and positron emission tomography (P.E.T). Psychometric evaluations of demented patients were correlated with a significant diminution of protein synthesis in the frontal area. This diminution was lower in ebephrenic patients (-17%) but was consistent with the results obtained with /sup 18/F glucose. No significant abnormality was detected in patients with Parkinson disease.
Effect of different levels of L-carnitine and lysine-methionine on broiler blood parameters

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Babak Hosseintabar

2015-09-01

Full Text Available Objetive. In the present study a completely randomized 3×3 factorial design was used to analyze the effects of different levels of L-Carnitine, lysine(Lys and methionine (Met on the blood concentrations of energy, protein and lipid metabolites of male broiler chickens. Materials and methods. A total of 270 newly hatched male broiler chickens (Ross 308 were randomly assigned to 9 groups (ten broilers per replicate and three replicates per treatment. The control group was fed a basal diet, whereas the treatment groups were fed basal diets supplemented with L-Carnitine (0 mg/kg, 75 mg/kg and 150 mg/kg and lysine-methionine (0, 15 and 30% for 42 days. On day 42, one bird was randomly chosen per replication, a blood sample was taken and the blood concentrations of glucose (GLU, uric acid (UAc, triglyceride (TG, VLDL, HDL, LDL, total protein (TP, albumin (Alb and total cholesterol (TC were analyzed. Results. Dietary L-carnitine supplementation had a significant effect (p<0.05 on uric acid (UAc, HDL, LDL, and total cholesterol (TC. The birds feed L-carnitine plus Lys and Met presented the highest plasmatic UAc level and the lowest plasmatic TC and LDL level. Moreover, L-carnitine significantly reduced total cholesterol (TC when compared with both the control group and the birds feed Lys and Met without L-carnitine. Conclusions. A diet with 150 mg/kg L-carnitine plus 15% Lys and Met seems to be enough to sustain low plasmatic TC, LDL and HDL concentrations on male broiler.
Structure-Function Analyses of a Caffeic Acid O-Methyltransferase from Perennial Ryegrass Reveal the Molecular Basis for Substrate Preference[W][OA

Science.gov (United States)

Louie, Gordon V.; Bowman, Marianne E.; Tu, Yi; Mouradov, Aidyn; Spangenberg, German; Noel, Joseph P.

2010-01-01

Lignin forms from the polymerization of phenylpropanoid-derived building blocks (the monolignols), whose modification through hydroxylation and O-methylation modulates the chemical and physical properties of the lignin polymer. The enzyme caffeic acid O-methyltransferase (COMT) is central to lignin biosynthesis. It is often targeted in attempts to engineer the lignin composition of transgenic plants for improved forage digestibility, pulping efficiency, or utility in biofuel production. Despite intensive investigation, the structural determinants of the regiospecificity and substrate selectivity of COMT remain poorly defined. Reported here are x-ray crystallographic structures of perennial ryegrass (Lolium perenne) COMT (Lp OMT1) in open conformational state, apo- and holoenzyme forms and, most significantly, in a closed conformational state complexed with the products S-adenosyl-l-homocysteine and sinapaldehyde. The product-bound complex reveals the post-methyl-transfer organization of COMT’s catalytic groups with reactant molecules and the fully formed phenolic-ligand binding site. The core scaffold of the phenolic ligand forges a hydrogen-bonding network involving the 4-hydroxy group that anchors the aromatic ring and thereby permits only metahydroxyl groups to be positioned for transmethylation. While distal from the site of transmethylation, the propanoid tail substituent governs the kinetic preference of ryegrass COMT for aldehydes over alcohols and acids due to a single hydrogen bond donor for the C9 oxygenated moiety dictating the preference for an aldehyde. PMID:21177481
SAH derived potent and selective EZH2 inhibitors

Energy Technology Data Exchange (ETDEWEB)

Kung, Pei-Pei; Huang, Buwen; Zehnder, Luke; Tatlock, John; Bingham, Patrick; Krivacic, Cody; Gajiwala, Ketan; Diehl, Wade; Yu, Xiu; Maegley, Karen A.

2015-04-01

A series of novel enhancer of zeste homolog 2 (EZH2) inhibitors was designed based on the chemical structure of the histone methyltransferase (HMT) inhibitor SAH (S-adenosyl-l-homocysteine). These nucleoside-based EZH2 inhibitors blocked the methylation of nucleosomes at H3K27 in biochemical assays employing both WT PRC2 complex as well as a Y641N mutant PRC2 complex. The most potent compound, 27, displayed IC50’s against both complexes of 270 nM and 70 nM, respectively. To our knowledge, compound 27 is the most potent SAH-derived inhibitor of the EZH2 PRC2 complex yet identified. This compound also displayed improved potency, lipophilic efficiency (LipE), and selectivity profile against other lysine methyltransferases compared with SAH.
Effect of Enhancers on in vitro and in vivo Skin Permeation and Deposition of S-Methyl-L-Methionine.

Science.gov (United States)

Kim, Ki Taek; Kim, Ji Su; Kim, Min-Hwan; Park, Ju-Hwan; Lee, Jae-Young; Lee, WooIn; Min, Kyung Kuk; Song, Min Gyu; Choi, Choon-Young; Kim, Won-Serk; Oh, Hee Kyung; Kim, Dae-Duk

2017-07-01

S-methyl- L -methionine (SMM), also known as vitamin U, is commercially available as skin care cosmetic products for its wound healing and photoprotective effects. However, the low skin permeation expected of SMM due to its hydrophilic nature with a log P value of -3.3, has not been thoroughly addressed. The purpose of this study thus was to evaluate the effect of skin permeation enhancers on the skin permeation/deposition of SMM. Among the enhancers tested for the in vitro skin permeation and deposition of SMM, oleic acid showed the most significant enhancing effect. Moreover, the combination of oleic acid and ethanol further enhanced in vitro permeation and deposition of SMM through hairless mouse skin. Furthermore, the combination of oleic acid and ethanol significantly increased the in vivo deposition of SMM in the epidermis/dermis for 12 hr, which was high enough to exert a therapeutic effect. Therefore, based on the in vitro and in vivo studies, the combination of oleic acid and ethanol was shown to be effective in improving the topical skin delivery of SMM, which may be applied in the cosmetic production process for SMM.
Lean Body Mass Harbors Sensing Mechanisms that Allow Safeguarding of Methionine Homeostasis.

Science.gov (United States)

Ingenbleek, Yves

2017-09-20

Protein-depleted states generate allosteric inhibition of liver cystathionine β-synthase (CBS), which governs the first enzymatic step of the transsulfuration cascade, resulting in upstream accretion of homocysteine (Hcy) in body fluids. A similar Hcy increase may arise from normal hepatocytes undergoing experimentally-induced impairment of betaine-homocysteine methyltransferase (BHTM) activity or from components of lean body mass (LBM) submitted to any inflammatory disorder. LBM comprises a composite agglomeration of extrarenal tissues characterized by naturally occurring BHTM inactivity. As a result of cellular injury, LBM releases high concentrations of Hcy into the extracellular space, contrasting with the disruption of normal remethylation pathways. Hyperhomocysteinemia acts as a biomarker, reflecting the severity of insult and operating as an alarm signal. Elevated Hcy levels constitute a precursor pool recognized by a CBS coding region that reacts to meet increased methionine requirements in LBM tissues, using its enhanced production in hepatocytes. Preservation of methionine homeostasis benefits from its high metabolic priority and survival value.
Lean Body Mass Harbors Sensing Mechanisms that Allow Safeguarding of Methionine Homeostasis

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Yves Ingenbleek

2017-09-01

Full Text Available Protein-depleted states generate allosteric inhibition of liver cystathionine β-synthase (CBS, which governs the first enzymatic step of the transsulfuration cascade, resulting in upstream accretion of homocysteine (Hcy in body fluids. A similar Hcy increase may arise from normal hepatocytes undergoing experimentally-induced impairment of betaine-homocysteine methyltransferase (BHTM activity or from components of lean body mass (LBM submitted to any inflammatory disorder. LBM comprises a composite agglomeration of extrarenal tissues characterized by naturally occurring BHTM inactivity. As a result of cellular injury, LBM releases high concentrations of Hcy into the extracellular space, contrasting with the disruption of normal remethylation pathways. Hyperhomocysteinemia acts as a biomarker, reflecting the severity of insult and operating as an alarm signal. Elevated Hcy levels constitute a precursor pool recognized by a CBS coding region that reacts to meet increased methionine requirements in LBM tissues, using its enhanced production in hepatocytes. Preservation of methionine homeostasis benefits from its high metabolic priority and survival value.
Steric Clash in the SET Domain of Histone Methyltransferase NSD1 as a Cause of Sotos Syndrome and Its Genetic Heterogeneity in a Brazilian Cohort

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Kyungsoo Ha

2016-11-01

Full Text Available Most histone methyltransferases (HMTase harbor a predicted Su(var3–9, Enhancer-of-zeste, Trithorax (SET domain, which transfers a methyl group to a lysine residue in their substrates. Mutations of the SET domains were reported to cause intellectual disability syndromes such as Sotos, Weaver, or Kabuki syndromes. Sotos syndrome is an overgrowth syndrome with intellectual disability caused by haploinsufficiency of the nuclear receptor binding SET domain protein 1 (NSD1 gene, an HMTase at 5q35.2–35.3. Here, we analyzed NSD1 in 34 Brazilian Sotos patients and identified three novel and eight known mutations. Using protein modeling and bioinformatic approaches, we evaluated the effects of one novel (I2007F and 21 previously reported missense mutations in the SET domain. For the I2007F mutation, we observed conformational change and loss of structural stability in Molecular Dynamics (MD simulations which may lead to loss-of-function of the SET domain. For six mutations near the ligand-binding site we observed in simulations steric clashes with neighboring side chains near the substrate S-Adenosyl methionine (SAM binding site, which may disrupt the enzymatic activity of NSD1. These results point to a structural mechanism underlying the pathology of the NSD1 missense mutations in the SET domain in Sotos syndrome. NSD1 mutations were identified in only 32% of the Brazilian Sotos patients in our study cohort suggesting other genes (including unknown disease genes underlie the molecular etiology for the majority of these patients. Our studies also found NSD1 expression to be profound in human fetal brain and cerebellum, accounting for prenatal onset and hypoplasia of cerebellar vermis seen in Sotos syndrome.
Necrosis-Driven Systemic Immune Response Alters SAM Metabolism through the FOXO-GNMT Axis

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Fumiaki Obata

2014-05-01

Full Text Available Sterile inflammation triggered by endogenous factors is thought to contribute to the pathogenesis of acute and chronic inflammatory diseases. Here, we demonstrate that apoptosis-deficient mutants spontaneously develop a necrosis-driven systemic immune response in Drosophila and provide an in vivo model for studying the organismal response to sterile inflammation. Metabolomic analysis of hemolymph from apoptosis-deficient mutants revealed increased sarcosine and reduced S-adenosyl-methionine (SAM levels due to glycine N-methyltransferase (Gnmt upregulation. We showed that Gnmt was elevated in response to Toll activation induced by the local necrosis of wing epidermal cells. Necrosis-driven inflammatory conditions induced dFoxO hyperactivation, leading to an energy-wasting phenotype. Gnmt was cell-autonomously upregulated by dFoxO in the fat body as a possible rheostat for controlling energy loss, which functioned during fasting as well as inflammatory conditions. We propose that the dFoxO-Gnmt axis is essential for the maintenance of organismal SAM metabolism and energy homeostasis.

Structure-function analyses of a caffeic acid O-methyltransferase from perennial ryegrass reveal the molecular basis for substrate preference.

Science.gov (United States)

Louie, Gordon V; Bowman, Marianne E; Tu, Yi; Mouradov, Aidyn; Spangenberg, German; Noel, Joseph P

2010-12-01

Lignin forms from the polymerization of phenylpropanoid-derived building blocks (the monolignols), whose modification through hydroxylation and O-methylation modulates the chemical and physical properties of the lignin polymer. The enzyme caffeic acid O-methyltransferase (COMT) is central to lignin biosynthesis. It is often targeted in attempts to engineer the lignin composition of transgenic plants for improved forage digestibility, pulping efficiency, or utility in biofuel production. Despite intensive investigation, the structural determinants of the regiospecificity and substrate selectivity of COMT remain poorly defined. Reported here are x-ray crystallographic structures of perennial ryegrass (Lolium perenne) COMT (Lp OMT1) in open conformational state, apo- and holoenzyme forms and, most significantly, in a closed conformational state complexed with the products S-adenosyl-L-homocysteine and sinapaldehyde. The product-bound complex reveals the post-methyl-transfer organization of COMT's catalytic groups with reactant molecules and the fully formed phenolic-ligand binding site. The core scaffold of the phenolic ligand forges a hydrogen-bonding network involving the 4-hydroxy group that anchors the aromatic ring and thereby permits only metahydroxyl groups to be positioned for transmethylation. While distal from the site of transmethylation, the propanoid tail substituent governs the kinetic preference of ryegrass COMT for aldehydes over alcohols and acids due to a single hydrogen bond donor for the C9 oxygenated moiety dictating the preference for an aldehyde.
Evaluations of the trans-sulfuration pathway in multiple liver toxicity studies

International Nuclear Information System (INIS)

Schnackenberg, Laura K.; Chen Minjun; Sun, Jinchun; Holland, Ricky D.; Dragan, Yvonne; Tong Weida; Welsh, William; Beger, Richard D.

2009-01-01

Drug-induced liver injury has been associated with the generation of reactive metabolites, which are primarily detoxified via glutathione conjugation. In this study, it was hypothesized that molecules involved in the synthesis of glutathione would be diminished to replenish the glutathione depleted through conjugation reactions. Since S-adenosylmethionine (SAMe) is the primary source of the sulfur atom in glutathione, UPLC/MS and NMR were used to evaluate metabolites involved with the transulfuration pathway in urine samples collected during studies of eight liver toxic compounds in Sprague-Dawley rats. Urinary levels of creatine were increased on day 1 or day 2 in 8 high dose liver toxicity studies. Taurine concentration in urine was increased in only 3 of 8 liver toxicity studies while SAMe was found to be reduced in 4 of 5 liver toxicity studies. To further validate the results from the metabonomic studies, microarray data from rat liver samples following treatment with acetaminophen was obtained from the Gene Expression Omnibus (GEO) database. Some genes involved in the trans-sulfuration pathway, including guanidinoacetate N-methyltransferase, glycine N-methyltransferase, betaine-homocysteine methyltransferase and cysteine dioxygenase were found to be significantly decreased while methionine adenosyl transferase II, alpha increased at 24 h post-dosing, which is consistent with the SAMe and creatine findings. The metabolic and transcriptomic results show that the trans-sulfuration pathway from SAMe to glutathione was disturbed due to the administration of heptatotoxicants
The enzymatic activities of brain catechol-O-methyltransferase (COMT) and methionine sulphoxide reductase are correlated in a COMT Val/Met allele-dependent fashion.

Science.gov (United States)

Moskovitz, Jackob; Walss-Bass, Consuelo; Cruz, Dianne A; Thompson, Peter M; Hairston, Jenaqua; Bortolato, Marco

2015-12-01

The enzyme catechol-O-methyltransferase (COMT) plays a primary role in the metabolism of catecholamine neurotransmitters and is implicated in the modulation of cognitive and emotional responses. The best characterized single nucleotide polymorphism (SNP) of the COMT gene consists of a valine (Val)-to-methionine (Met) substitution at codon 108/158. The Met-containing variant confers a marked reduction in COMT catalytic activity. We recently showed that the activity of recombinant COMT is positively regulated by the enzyme Met sulphoxide reductase (MSR), which counters the oxidation of Met residues of proteins. The current study was designed to assess whether brain COMT activity may be correlated to MSR in an allele-dependent fashion. COMT and MSR activities were measured from post-mortem samples of prefrontal cortices, striata and cerebella of 32 subjects by using catechol and dabsyl-Met sulphoxide as substrates, respectively. Allelic discrimination of COMT Val(108/185) Met SNP was performed using the Taqman 5'nuclease assay. Our studies revealed that, in homozygous carriers of Met, but not Val alleles, the activity of COMT and MSR was significantly correlated throughout all tested brain regions. These results suggest that the reduced enzymatic activity of Met-containing COMT may be secondary to Met sulphoxidation and point to MSR as a key molecular determinant for the modulation of COMT activity. © 2015 British Neuropathological Society.
MAT1A variants are associated with hypertension, stroke, and DNA damage and are modulated by vlasma vitamin B6 and folate concentration

Science.gov (United States)

Elevated plasma homocysteine is a cardiovascular disease (CVD) risk factor. However, the mechanism underlying this relationship is not understood. S-adenosylmethionine synthetase isoform type-1 (MAT1A) is a key enzyme in the metabolism of homocysteine, converting dietary methionine into S-adenosyl m...
Bio-Inspired Nitrile Hydration by Peptidic Ligands Based on L-Cysteine, L-Methionine or L-Penicillamine and Pyridine-2,6-dicarboxylic Acid

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Cillian Byrne

2014-12-01

Full Text Available Nitrile hydratase (NHase, EC 4.2.1.84 is a metalloenzyme which catalyses the conversion of nitriles to amides. The high efficiency and broad substrate range of NHase have led to the successful application of this enzyme as a biocatalyst in the industrial syntheses of acrylamide and nicotinamide and in the bioremediation of nitrile waste. Crystal structures of both cobalt(III- and iron(III-dependent NHases reveal an unusual metal binding motif made up from six sequential amino acids and comprising two amide nitrogens from the peptide backbone and three cysteine-derived sulfur ligands, each at a different oxidation state (thiolate, sulfenate and sulfinate. Based on the active site geometry revealed by these crystal structures, we have designed a series of small-molecule ligands which integrate essential features of the NHase metal binding motif into a readily accessible peptide environment. We report the synthesis of ligands based on a pyridine-2,6-dicarboxylic acid scaffold and L-cysteine, L-S-methylcysteine, L-methionine or L-penicillamine. These ligands have been combined with cobalt(III and iron(III and tested as catalysts for biomimetic nitrile hydration. The highest levels of activity are observed with the L-penicillamine ligand which, in combination with cobalt(III, converts acetonitrile to acetamide at 1.25 turnovers and benzonitrile to benzamide at 1.20 turnovers.
Simultaneous Determination of Hydroquinone and Catechol by Poly (L-methionine Coated Hydroxyl Multiwalled Carbon Nanotube Film

Directory of Open Access Journals (Sweden)

Ying Zhang

2014-07-01

Full Text Available A simply and high selectively electrochemical method has been developed for the simultaneous determination of hydroquinone and catechol at a glassy carbon electrode modified with the poly L-methionine/multiwall carbon nanotubes, which significantly increased the reversible electrochemical reaction. The electrochemical behavior of catechol and hydroquinone at the modified electrode was studied by cyclic voltammetry and differential pulse voltammetry. The presence of hydroxyl MWCNTs in the composite film enhances the surface coverage concentration of poly L- methionine/multiwall carbon nanotubes. The results suggest that pH=6 is the optimum acidity condition for the selective and simultaneous determination of catechol and hydroquinone. Under the optimized condition, the response peak currents of the modified electrodes were linear over ranges of 8.0´10-7~2.0´10-4 mol/L (R2=0.997 for hydroquinone and 8.0´10-7~2.0´10-4, R2=0.997 for catechol. The sensor also exhibited good sensitivity with the detection limit of 8.0´10-8 mol/L and 1.0´10- 7 mol/L for hydroquinone and catechol, respectively. This study provides a new kind of composite modified electrode for electrochemical sensors with good selectivity and strong anti- interference. It has been applied to simultaneous determination of hydroquinone and catechol in water sample with simplicity and high selectivity.
Protein: MPA1 [TP Atlas

Lifescience Database Archive (English)

Full Text Available MPA1 TLR signaling molecules Rsad2 Vig1 Radical S-adenosyl methionine domain-containing pr...otein 2 Viperin, Virus inhibitory protein, endoplasmic reticulum-associated, interferon-inducible 10090 Mus musculus 58185 Q8CBB9 21435586 ...
[Gene cloning and bioinformatics analysis of SABATH methyltransferase in Lonicera japonica var. chinensis].

Science.gov (United States)

Yu, Xiao-Dan; Jiang, Chao; Huang, Lu-Qi; Qin, Shuang-Shuang; Zeng, Xiang-Mei; Chen, Ping; Yuan, Yuan

2013-08-01

To clone SABATH methyltransferase (rLjSABATHMT) gene in Lonicera japonica var. chinensis, and compare the gene expression and intron sequence of SABATH methyltransferase orthologous in L. japonica with L. japonica var. chinensis. It provide a basis for gene regulate the formation of L. japonica floral scents. The cDNA and genome sequences of LjSABATHMT from L. japonica var. chinensis were cloned according to the gene fragments in cDNA library. The LjSABATHMT protein was characterized by bioinformatics analysis. SABATH family phylogenetic tree were built by MEGA 5.0. The transcripted level of SABATHMT orthologous were analyzed in different organs and different flower periods of L. japonica and L. japonica var. chinensis using RT-PCR analysis. Intron sequences of SABATHMT orthologous were also analyzied. The cDNA of LjSABATHMT was 1 251 bp, had a complete coding frame with 365 amino acids. The protein had the conservative SABATHMT domain, and phylogenetic tree showed that it may be a salicylic acid/benzoic acid methyltransferase. Higher expression of SABATH methyltransferase orthologous was found in flower. The intron sequence of L. japonica and L. japonica var. chinensis had rich polymorphism, and two SNP are unique genotype of L. japonica var. chinensis. The motif elements in two orthologous genes were significant differences. The intron difference of SABATH methyltransferase orthologous could be inducing to difference of gene expression between L. japonica and L. japonica var. chinensis. These results will provide important base on regulating active compounds of L. japonica.
Domain V of 23S rRNA contains all the structural elements necessary for recognition by the ErmE methyltransferase

DEFF Research Database (Denmark)

Vester, B; Douthwaite, S

1994-01-01

investigated what structural elements in 23S rRNA are required for specific recognition by the ErmE methyltransferase. The ermE gene was cloned into R1 plasmid derivatives, providing a means of inducible expression in Escherichia coli. Expression of the methyltransferase in vivo confers resistance......, and the enzyme efficiently modifies 23S rRNA in vitro. Removal of most of the 23S rRNA structure, so that only domain V (nucleotides 2000 to 2624) remains, does not affect the efficiency of modification by the methyltransferase. In addition, modification still occurs after the rRNA tertiary structure has been...
Stabilization of sulfide cations: mechanisms relevant to oxidation of peptides and proteins containing methionine

International Nuclear Information System (INIS)

Bobrowski, K.; Hug, G.L.; Pogocki, D.; Horner, G.; Marciniak, B.; Schoneich, C.

2006-01-01

compounds for the study of peptide free radical chemistry. While appearing very small to be models for proteins, they have unique feature of having no terminal groups. This makes them invaluable for studying interactions between side chains and peptide bonds. A small model cyclic dipeptide c-(L-methionyl-L-methionine) was oxidized by . OH radicals generated via pulse radiolysis, and the ensuing reactive intermediates were monitored by time-resolved UV/Vis spectroscopic and conductometric techniques. The picture that emerged from this investigation showed there was an efficient formation of the Met(S N) radicals, in spite of the close proximity of sulfur atoms, located in the side chain of methionine residues, and in spite of the close proximity of sulfur atoms and oxygen atoms, located in the peptide bonds. Moreover, it was observed, for the first time, that formation of Met(S N) radicals involved the hydrogen atom of the peptide bond. In this concerted process, elimination of OH in the form of water involves a simultaneous N-deprotonation from the amide nitrogen, followed by formation of Met(S N) radicals in the form of a thermodynamically favorable five-membered ring. These Met(S N) radicals converted further into intramolecular three-electron bonded Met(S S) + and Met(S O) + radical cations via a pH-dependent mechanism. A preference for Met(S+ ) stabilization in the form of intramolecular three-electron bonded Met(S N) radicals over intermolecular three-electron bonded Met(S S)+ dimeric radical cations was observed in c-(L-Met-D-Met). Lack of intramolecular three-electron bonded Met(S S)+ radical cations illustrates that a close contact between two sulfur atoms is sterically restricted in the D-L enantiomer. Moreover, contrary to c-(L-Met-L-Met), most of Met(S+ ) radicals derived from c-(L-Met-D-Met) undergo efficient deprotonation in the α-position to the sulfur, yielding carbon-centered α-(alkylthio)alkyl radicals. To support the mechanism, quantum mechanical (DFT
EFFICACY OF REMAXOL AND ADEMETHIONINE IN EXPERIMENTAL LIVER DAMAGE CAUSED BY A COMBINATION OF RESERVE-SERIES ANTITUBERCULOSIS DRUGS AND ALCOHOL

Directory of Open Access Journals (Sweden)

D. S. Sukhanov

2014-01-01

Full Text Available The hepatic and endothelial protective effects of remaxol and S-adenosyl-L-methionine were studied on 24 male rats with liver damage caused by reserve-series antituberculosis drugs in combination with alcohol. The test agents were found to have a unilateral hepatoprotective effect in decreasing the blood levels of triglycerides, bilirubin, and alkaline phosphatase with a concurrent significant reduction in the manifestations of hyaline-drop and hydropic dystrophy of hepatocytes. Remaxol and ademethionine have the same endothelial protective activity manifested as normalization of an endothelium-dependent vasodilation response and endothelial dysfunction coefficient.
Stereochemical course of enzyme-catalyzed aminopropyl transfer: spermidine synthase

International Nuclear Information System (INIS)

Kullberg, D.W.; Orr, G.R.; Coward, J.K.

1986-01-01

The R and S enantionmers of S-adenosyl-3-[ 2 H]3-(methylthio)-1-propylamine (decarboxylated S-adenosylmethionine), previously synthesized in this laboratory, were incubated with [1,4- 2 H 4 ]-putrescine in the presence of spermidine synthase from E. coli. The resulting chiral [ 2 H 5 ]spermidines were isolated and converted to their N 1 ,N 7 -dibocspermidine-N 4 -(1S,4R)-camphanamides. The derivatives were analyzed by 500 MHz 1 H-NMR and the configuration of the chiral center assigned by correlation with the spectra of synthetic chiral [ 2 H 3 ]dibocspermidine camphanamide standards. The enzyme-catalyzed aminopropyl transfer was shown to occur with net retention of configuration, indicative of a double-displacement mechanism. This result concurs with that of a previous steady-state kinetics study of spermidine synthase isolated from E. coli, but contradicts the single-displacement mechanism suggested by a stereochemical analysis of chiral spermidines biosynthesized in E. coli treated with chirally deuterated methionines. It also indicates that this aminopropyltransferase is mechanistically distinct from the methyltransferases, which have been shown to act via a single-displacement mechanism (net inversion at -CH 3 ) in all cases studied to date
Polyamines and polyamine biosynthesis in cells exposed to hyperthermia

Energy Technology Data Exchange (ETDEWEB)

Gerner, E.W.; Stickney, D.G.; Herman, T.S.; Fuller, D.J.

1983-02-01

The issue of how polyamines act to sensitize cultured cells to the lethal effects of hyperthermia was investigated using Chinese hamster cells which were induced to express thermotolerance. Intracellular levels of these naturally occurring polycations were manipulated in certain situations by treating whole cells with methylglyoxal bis-(guanylhydrazone), an inhibitor of the S-adenosyl-L-methionine decarboxylases. Exogenous spermine as low as 100 ..mu..M in the culture media dramatically sensitized cells expressing thermotolerance to the lethal effects of subsequent 42/sup 0/C exposures. When thermotolerance was differentially induced in cultures exposed to 42.4/sup 0/C by varying the rate of heating from 37 to 42.4/sup 0/C, the most resistant cells and the highest levels of intracellular spermidine and spermine. This finding was explainable in part by the observation that the putrescine-dependent S-adenosyl-L-methionine decarboxylase activity was minimally affected in cells expressng the greatest degree of thermotolerance. When this enzyme activity was inhibited by drug, lowered intracellular polyamine levels did not correspond with subsequent survival responses to heat. Interestingly, cultures treated with methylglyoxal bis-(guanylhydrazone) 24 hr previous to heat exposure showed a reduced capacity to express rate of heating-induced thermotolerance. Together, these results demonstrate that the polyamines, especially spermidine and spermine, enhance hyperthermia-induced cell killing by some mechanism involving the plasma membrane. Further, our data suggest that methylglyoxal bis-(guanylhydrazone) can act to affect thermal responses by a mechanism(s) other than modification of intracellular polyamine levels.
Proteins differentially expressed in elicited cell suspension culture of Podophyllum hexandrum with enhanced podophyllotoxin content

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Bhattacharyya Dipto

2012-05-01

Full Text Available Abstract Background Podophyllotoxin (PTOX, the precursor for semi-synthesis of cancer therapeutics like etoposide, teniposide and etophos, is primarily obtained from an endangered medicinal herb, Podophyllum hexandrum Royle. PTOX, a lignan is biosynthetically derived from the phenylpropanoid pathway. The aim of this study is to investigate changes in the P. hexandrum cell proteome potentially related to PTOX accumulation in response to methyl jasmonate (MeJA elicitation. High-resolution two-dimensional gel electrophoresis (2-DE followed by colloidal Coomassie staining and mass spectrometric analysis was used to detect statistically significant changes in cell’s proteome. Result The HPLC analysis showed approximately 7–8 fold change in accumulation of PTOX, in the 12day old cell suspension culture (i.e. after 9days of elicitation elicited with 100 μM MeJA as compared to the control. Using 2-DE a total of 233 spots was detected, out of which 105 spots were identified by MALDI TOF-TOF MS/MS. Data were subjected to functional annotation from a biological point of view through KEGG. The phenylpropanoid and monolignol pathway enzymes were identified, amongst these, chalcone synthase, polyphenol oxidase, caffeoyl CoA 3-O-methyltransferase, S-adenosyl-L-methionine-dependent methyltransferases, caffeic acid-O-methyl transferase etc. are noted as important. The relation of other differentially accumulated proteins with varied effects caused by elicitors on P. hexandrum cells namely stress and defense related protein, transcription and DNA replication and signaling are also discussed. Conclusions Elicitor-induced PTOX accumulation in P. hexandrum cell cultures provides a responsive model system to profile modulations in proteins related to phenylpropanoid/monolignol biosynthesis and other defense responses. Present findings form a baseline for future investigation on a non-sequenced medicinal herb P. hexandrum at molecular level.
Nuclear magnetic resonance studies of amino acids and proteins. Side-chain mobility of methionine in the crystalline amonio acid and in crystallne sperm whale (Physeter catodon) myoglobin

International Nuclear Information System (INIS)

Keniry, M.A.; Rothgeb, T.M.; Smith, R.L.; Gutowsky, H.S.; Oldfield, E.

1983-01-01

Deuterium ( 2 H) nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times (T 1 ) were obtained of L-[epsilon- 2 H 3 ]methionine, L-[epsilon- 2 H 3 ]methionine in a D,L lattice, and [S-methyl- 2 H 3 ]methionine in the crystalline solid state, as a function of temperature, in addition to obtaining 2 H T 1 and line-width results as a function of temperature on [epsilon- 2 H 3 ]methionine-labeled sperm whale (Physeter catodon) myoglobins by using the method of magnetic ordering. Also recorded were 13 C cross-polarization ''magic-angle'' sample-spinning NMR spectra of [epsilon- 13 C]methionine-labeled crystalline cyanoferrimyoglobin (at 37.7 MHz, corresponding to a magnetic field strength of 3.52 T) and of the same protein in aqueous solution
Arabidopsis DNA methyltransferase AtDNMT2 associates with histone deacetylase AtHD2s activity

International Nuclear Information System (INIS)

Song, Yuan; Wu, Keqiang; Dhaubhadel, Sangeeta; An, Lizhe; Tian, Lining

2010-01-01

DNA methyltransferase2 (DNMT2) is always deemed to be enigmatic, because it contains highly conserved DNA methyltransferase motifs but lacks the DNA methylation catalytic capability. Here we show that Arabidopsis DNA methyltransferase2 (AtDNMT2) is localized in nucleus and associates with histone deacetylation. Bimolecular fluorescence complementation and pull-down assays show AtDNMT2 interacts with type-2 histone deacetylases (AtHD2s), a unique type of histone deacetylase family in plants. Through analyzing the expression of AtDNMT2: ss-glucuronidase (GUS) fusion protein, we demonstrate that AtDNMT2 has the ability to repress gene expression at transcription level. Meanwhile, the expression of AtDNMT2 gene is altered in athd2c mutant plants. We propose that AtDNMT2 possibly involves in the activity of histone deacetylation and plant epigenetic regulatory network.
Arabidopsis DNA methyltransferase AtDNMT2 associates with histone deacetylase AtHD2s activity

Energy Technology Data Exchange (ETDEWEB)

Song, Yuan [Key Laboratory of Arid and Grassland Agroecology, Ministry of Education, School of Life Science, Lanzhou University, Lanzhou 730000 (China); Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON, Canada N5V4T3 (Canada); Wu, Keqiang [Institute of Plant Biology, National Taiwan University, Taipei 106, Taiwan (China); Dhaubhadel, Sangeeta [Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON, Canada N5V4T3 (Canada); An, Lizhe, E-mail: lizhean@lzu.edu.cn [Key Laboratory of Arid and Grassland Agroecology, Ministry of Education, School of Life Science, Lanzhou University, Lanzhou 730000 (China); Tian, Lining, E-mail: tianl@agr.gc.ca [Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON, Canada N5V4T3 (Canada)

2010-05-28

DNA methyltransferase2 (DNMT2) is always deemed to be enigmatic, because it contains highly conserved DNA methyltransferase motifs but lacks the DNA methylation catalytic capability. Here we show that Arabidopsis DNA methyltransferase2 (AtDNMT2) is localized in nucleus and associates with histone deacetylation. Bimolecular fluorescence complementation and pull-down assays show AtDNMT2 interacts with type-2 histone deacetylases (AtHD2s), a unique type of histone deacetylase family in plants. Through analyzing the expression of AtDNMT2: ss-glucuronidase (GUS) fusion protein, we demonstrate that AtDNMT2 has the ability to repress gene expression at transcription level. Meanwhile, the expression of AtDNMT2 gene is altered in athd2c mutant plants. We propose that AtDNMT2 possibly involves in the activity of histone deacetylation and plant epigenetic regulatory network.
A specific radioenzymatic assay for dihydroxyphenylalanine (DOPA). Plasma DOPA may be the precursor of urine free dopamine

International Nuclear Information System (INIS)

Brown, M.J.; Dollery, C.T.

1981-01-01

A sensitive radioenzymatic assay was developed, in which DOPA is enzymatically decarboxylated to dopamine and the latter converted to [ 3 H]-methoxytryamine in the presence of [ 3 H]-S-adenosyl-L-methionine and catechol-o-methyltransferase. The assay was specific for DOPA, and was sensitive to 50 pg/ml. Endogenous DOPA was found to be present in the plasma of eight human volunteers at a concentration of 10.46 +- 2.42 nmol/l. Simultaneous urine collections in the same subjects showed a free dopamine excretion of 68.88 +- 17.70 nmol/h. There was a significant correlation (P < 0.01) between plasma DOPA concentration and urine free dopamine excretion (r = 0.84). After the oral administration of 250 mg levodopa, plasma DOPA and urine dopamine both increased by a similar proportion (98 +- 8.4-fold, and 93.4 +- 6.9-fold respectively). These compare with an increase in plasma dopamine of only 26 +- 15-fold (P<0.01). Following the oral dose of DOPA, the increase in plasma DOPA, but not plasma dopamine, could account for the increase in urine dopamine. The calculated clearance of plasma DOPA by renal decarboxylation to dopamine was 114 +- 20 ml/min. This is not significantly different from the apparent clearance of endogenous DOPA by renal decarboxylation to dopamine, and suggests that there is adequate renal decarboxylase activity for DOPA to be the precursor for renal dopamine formation. (author)
Modeling of the adsorptive removal of arsenic(III) using plant biomass: a bioremedial approach

Science.gov (United States)

Roy, Palas; Dey, Uttiya; Chattoraj, Soumya; Mukhopadhyay, Debasis; Mondal, Naba Kumar

2017-06-01

In the present work, the possibility of using a non-conventional finely ground (250 μm) Azadirachta indica (neem) bark powder [AiBP] has been tested as a low-cost biosorbent for the removal of arsenic(III) from water. The removal of As(III) was studied by performing a series of biosorption experiments (batch and column). The biosorption behavior of As(III) for batch and column operations were examined in the concentration ranges of 50-500 µg L-1 and 500.0-2000.0 µg L-1, respectively. Under optimized batch conditions, the AiBP could remove up to 89.96 % of As(III) in water system. The artificial neural network (ANN) model was developed from batch experimental data sets which provided reasonable predictive performance ( R 2 = 0.961; 0.954) of As(III) biosorption. In batch operation, the initial As(III) concentration had the most significant impact on the biosorption process. For column operation, central composite design (CCD) was applied to investigate the influence on the breakthrough time for optimization of As(III) biosorption process and evaluation of interacting effects of different operating variables. The optimized result of CCD revealed that the AiBP was an effective and economically feasible biosorbent with maximum breakthrough time of 653.9 min, when the independent variables were retained at 2.0 g AiBP dose, 2000.0 µg L-1 initial As(III) concentrations, and 3.0 mL min-1 flow rate, at maximum desirability value of 0.969.
The Pseudomonas aeruginosa autoinducer dodecanoyl-homoserine lactone inhibits the putrescine synthesis in human cells

DEFF Research Database (Denmark)

Kristiansen, S.; Bjarnsholt, Thomas; Adeltoft, D.

2008-01-01

Pseudomonas aeruginosa uses acyl-homoserine lactones to coordinate gene transcription in a process called quorum sensing (QS). The QS molecules C-4-HSL and C-12-oxo-HSL are synthesized from the universal precursor S-adenosyl methionine, which is also a precursor of polyamines in human cells...

Structure of the human gene encoding the protein repair L-isoaspartyl (D-aspartyl) O-methyltransferase.

Science.gov (United States)

DeVry, C G; Tsai, W; Clarke, S

1996-11-15

The protein L-isoaspartyl/D-aspartyl O-methyltransferase (EC 2.1.1.77) catalyzes the first step in the repair of proteins damaged in the aging process by isomerization or racemization reactions at aspartyl and asparaginyl residues. A single gene has been localized to human chromosome 6 and multiple transcripts arising through alternative splicing have been identified. Restriction enzyme mapping, subcloning, and DNA sequence analysis of three overlapping clones from a human genomic library in bacteriophage P1 indicate that the gene spans approximately 60 kb and is composed of 8 exons interrupted by 7 introns. Analysis of intron/exon splice junctions reveals that all of the donor and acceptor splice sites are in agreement with the mammalian consensus splicing sequence. Determination of transcription initiation sites by primer extension analysis of poly(A)+ mRNA from human brain identifies multiple start sites, with a major site 159 nucleotides upstream from the ATG start codon. Sequence analysis of the 5'-untranslated region demonstrates several potential cis-acting DNA elements including SP1, ETF, AP1, AP2, ARE, XRE, CREB, MED-1, and half-palindromic ERE motifs. The promoter of this methyltransferase gene lacks an identifiable TATA box but is characterized by a CpG island which begins approximately 723 nucleotides upstream of the major transcriptional start site and extends through exon 1 and into the first intron. These features are characteristic of housekeeping genes and are consistent with the wide tissue distribution observed for this methyltransferase activity.
Structural insights into methyltransferase KsgA function in 30S ribosomal subunit biogenesis.

Science.gov (United States)

Boehringer, Daniel; O'Farrell, Heather C; Rife, Jason P; Ban, Nenad

2012-03-23

The assembly of the ribosomal subunits is facilitated by ribosome biogenesis factors. The universally conserved methyltransferase KsgA modifies two adjacent adenosine residues in the 3'-terminal helix 45 of the 16 S ribosomal RNA (rRNA). KsgA recognizes its substrate adenosine residues only in the context of a near mature 30S subunit and is required for the efficient processing of the rRNA termini during ribosome biogenesis. Here, we present the cryo-EM structure of KsgA bound to a nonmethylated 30S ribosomal subunit. The structure reveals that KsgA binds to the 30S platform with the catalytic N-terminal domain interacting with substrate adenosine residues in helix 45 and the C-terminal domain making extensive contacts to helix 27 and helix 24. KsgA excludes the penultimate rRNA helix 44 from adopting its position in the mature 30S subunit, blocking the formation of the decoding site and subunit joining. We suggest that the activation of methyltransferase activity and subsequent dissociation of KsgA control conformational changes in helix 44 required for final rRNA processing and translation initiation.
Structural Insights into Methyltransferase KsgA Function in 30S Ribosomal Subunit Biogenesis*

Science.gov (United States)

Boehringer, Daniel; O'Farrell, Heather C.; Rife, Jason P.; Ban, Nenad

2012-01-01

The assembly of the ribosomal subunits is facilitated by ribosome biogenesis factors. The universally conserved methyltransferase KsgA modifies two adjacent adenosine residues in the 3′-terminal helix 45 of the 16 S ribosomal RNA (rRNA). KsgA recognizes its substrate adenosine residues only in the context of a near mature 30S subunit and is required for the efficient processing of the rRNA termini during ribosome biogenesis. Here, we present the cryo-EM structure of KsgA bound to a nonmethylated 30S ribosomal subunit. The structure reveals that KsgA binds to the 30S platform with the catalytic N-terminal domain interacting with substrate adenosine residues in helix 45 and the C-terminal domain making extensive contacts to helix 27 and helix 24. KsgA excludes the penultimate rRNA helix 44 from adopting its position in the mature 30S subunit, blocking the formation of the decoding site and subunit joining. We suggest that the activation of methyltransferase activity and subsequent dissociation of KsgA control conformational changes in helix 44 required for final rRNA processing and translation initiation. PMID:22308031
Mechanism of oxidation of L-methionine by iron(III)

Indian Academy of Sciences (India)

phenanthroline complex have been studied in perchloric acid medium. The reaction is first order each in iron(III) and methionine. Increase in [phenanthroline] increases the rate while increase in [HClO4] decreases it. While the reactive species of the ...
A radioenzymatic technique for the measurement of free and conjugated 3,4-dihydroxyphenylethyleneglycol in brain tissue and biological fluids

International Nuclear Information System (INIS)

Dennis, T.; Scatton, B.

1982-01-01

A simple, sensitive and specific radioenzymatic assay for the measurement of 3,4-dihydroxyphenylethyleneglycol (DOPEG) was developed. The assay is based on the conversion of the compound to its O-methylated derivative in the presence of catechol-O-methyltransferase and [ 3 H]S-adenosyl-methionine. The tritiated 3-methoxy-4-hydroxyphenylethyleneglycol formed is selectively extracted in organic solvents and isolated by thin layer chromatography. After oxidation to vanillin the O-methylated compound is extracted and measured by liquid scintillation spectrophotometry. This assay has been applied to the measurement of free and conjugated DOPEG is a variety of biological tissues and fluids. Both free and conjugated DOPEG were readily detected in discrete rat brain areas. Substantial amounts of free and conjugated DOPEG were also measured in ventricular perfusates from freely moving rats. Finally, the presence of DOPEG was also demonstrated in human cerebrospinal fluid, plasma and urine. Only the free form of DOPEG was found in cerebrospinal fluid, whereas both unconjugated and conjugated forms were present in plasma and urine. (Auth.)
Cloning, expression, crystallization and preliminary X-ray analysis of the XMT and DXMT N-methyltransferases from Coffea canephora (robusta)

International Nuclear Information System (INIS)

McCarthy, Andrew A.; Biget, Laurent; Lin, Chenwei; Petiard, Vincent; Tanksley, Steve D.; McCarthy, James G.

2007-01-01

The genes encoding XMT and DXMT, the enzymes from Coffea canephora (robusta) that catalyse the three independent N-methyl transfer reactions in the caffeine-biosynthesis pathway, have been cloned and the proteins have been expressed in Escherichia coli. Both proteins have been crystallized in the presence of the demethylated cofactor S-adenosyl-l-cysteine (SAH) and substrate (xanthosine for XMT and theobromine for DXMT). Caffeine is a secondary metabolite produced by a variety of plants including Coffea canephora (robusta) and there is growing evidence that caffeine is part of a chemical defence strategy protecting young leaves and seeds from potential predators. The genes encoding XMT and DXMT, the enzymes from Coffea canephora (robusta) that catalyse the three independent N-methyl transfer reactions in the caffeine-biosynthesis pathway, have been cloned and the proteins have been expressed in Escherichia coli. Both proteins have been crystallized in the presence of the demethylated cofactor S-adenosyl-l-cysteine (SAH) and substrate (xanthosine for XMT and theobromine for DXMT). The crystals are orthorhombic, with space group P2 1 2 1 2 1 for XMT and C222 1 for DXMT. X-ray diffraction to 2.8 Å for XMT and to 2.5 Å for DXMT have been collected on beamline ID23-1 at the ESRF
A Fluorescent Assay for Plant Caffeic Acid O-methyltransferases

Science.gov (United States)

We have developed a facile, sensitive and continuous assay to measure the activities of plant COMTs using s-adenosyl homocysteine hydrolase as a coupling enzyme and and adeonsine a thiol-specific fluor, Thioglo1, as the detecting reagent. This assay was validated using recombinant sorghum COMT (BMR-...
Macro-and micro-autoradiographic study in comparison with the incorporation of 35S-methionine by various tissue protein in organism

International Nuclear Information System (INIS)

Zhu Shoupeng; Mei Shengping; Le Shangcheng

1990-12-01

The purpose of the study was to observe the incorporation level of 35 S-methionine by various tissue protein in organism. By the use of the macro-and micro-autoradiographic technique, the incorporation of 35 S-methionine by the tissues has been utilized as an index of various tissue protein synthesis. On this basis, the further experiments showed that tracer agent 35 S-methionine was dominantly incorporated in the immature cells of bone marrow and the tissue of liver, kidney and spleen. Its incorporation increased gradually with time. From the experimental results it can be concluded that a strong protein biosynthesis metabolism was produced in these tissues. While the tissues have important physiological function in organism, such as heart, lung and skeletal muscle, but the protein biosynthesis in those tissues was at a low level
Folic Acid Reduces Tau Phosphorylation by Regulating PP2A Methylation in Streptozotocin-Induced Diabetic Mice

Science.gov (United States)

Zheng, Miaoyan; Zou, Chen; Li, Mengyue; Huang, Guowei; Gao, Yuxia; Liu, Huan

2017-01-01

High incidence rate of Alzheimer’s disease (AD) is observed in patients with type 2 diabetes. Aggregated β-amyloid (Aβ) and hyperphosphorylated tau are the hallmarks of AD. Hyperphosphorylated tau has been detected in diabetic animals as well as in diabetic patients. Folates mediate the transfer of one carbon unit, required in various biochemical reactions. The effect of folate on tau phosphorylation in diabetic models still remains unknown. In this study, we investigated the effect and mechanism of folic acid on hyperphosphorylation of tau in streptozotocin (STZ)-induced diabetic mice. Diabetic mice induced by STZ, at the age of 10 weeks, were administered with three levels of folic acid: folic acid-deficient diet, diet with normal folic acid content, and 120 μg/kg folic acid diet for 8 weeks. Levels of serum folate and blood glucose were monitored. Tau phosphorylation, protein phosphatase 2A (PP2A) methylation, and Glycogen synthase kinase 3β (GSK-3β) phosphorylation were detected using Western blot. The S-adenosyl methionine:S-adenosyl homocysteine ratio (SAM:SAH) in brain tissues was also determined. DNA methyltransferase (DNMT) mRNA expression levels were detected using real-time PCR. Folic acid reduced tau hyperphosphorylation at Ser396 in the brain of diabetes mellitus (DM) mice. In addition, PP2A methylation and DNMT1 mRNA expression were significantly increased in DM mice post folic acid treatment. GSK-3β phosphorylation was not regulated by folic acid administration. Folic acid can reduce tau phosphorylation by regulating PP2A methylation in diabetic mice. These results support that folic acid can serve as a multitarget neuronal therapeutic agent for treating diabetes-associated cognitive dysfunction. PMID:28422052
Solid state radiolysis of sulphur-containing amino acids. Cysteine, cystine and methionine

International Nuclear Information System (INIS)

Franco Cataldo; Pietro Ragni; Susana Iglesias-Groth; Arturo Manchado

2011-01-01

The sulphur-containing proteinaceous amino acids l-cysteine, l-cystine and l-methionine were irradiated in the solid state to a dose of 3.2 MGy. This dose corresponds to that delivered by radionuclide decay in a timescale of 1.05 x 10 9 years to the organic matter buried at a depth >20 m in comets and asteroids. The purity of the sulphur-containing amino acids was studied by differential scanning calorimetry (DSC) before and after the solid state radiolysis and the preservation of the chirality after the radiolysis was studied by chirooptical methods (optical rotatory dispersion, ORD) and by FT-IR spectroscopy. Although the high radiation dose of 3.2 MGy delivered, all the amino acids studied show a high radiation resistance. The best radiation resistance was offered by l-cysteine. The radiolysis of l-cysteine leads to the formation of l-cystine. The radiation resistance of l-methionine is not at the level of l-cysteine but also l-methionine is able to survive the dose of 3.2 MGy. Furthermore in all cases examined the preservation of chirality after radiolysis was clearly observed by the ORD spectroscopy although a certain level of radioracemization was measured in all cases. The radioracemization is minimal in the case of l-cysteine and is more pronounced in the case of l-methionine. In conclusion, the study shows that the sulphur-containing amino acids can survive for 1.05 x 10 9 years and, after extrapolation of the data, even to the age of the Solar System i.e. to 4.6 x 10 9 years. (author)
Determination of S-methyl-L-methionine (SMM) from Brassicaceae Family Vegetables and Characterization of the Intestinal Transport of SMM by Caco-2 Cells.

Science.gov (United States)

Song, Ji-Hoon; Lee, Hae-Rim; Shim, Soon-Mi

2017-01-01

The objectives of the current study were to determine S-methyl-L-methionine (SMM) from various Brassicaceae family vegetables by using validated analytical method and to characterize the intestinal transport mechanism of SMM by the Caco-2 cells. The SMM is well known to provide therapeutic activity in peptic ulcers. The amount of SMM from various Brassicaceae family vegetables ranged from 89.08 ± 1.68 μg/g to 535.98 ± 4.85 μg/g of dry weight by using validated ultra-performance liquid chromatography-electrospray ionization-mass spectrometry method. For elucidating intestinal transport mechanism, the cells were incubated with or without transport inhibitors, energy source, or a metabolic inhibitor. Phloridzin and verapamil as inhibitors of sodium glucose transport protein (SGLT1) and P-glycoprotein, respectively, were not responsible for cellular uptake of SMM. Glucose and sodium azide were not affected by the cellular accumulation of SMM. The efflux ratio of SMM was 0.26, implying that it is not effluxed through Caco-2 cells. The apparent coefficient permeability (P app ) of SMM was 4.69 × 10 -5 cm/s, indicating that it will show good oral absorption in in vivo. © 2016 Institute of Food Technologists®.
Structure-activity study of new inhibitors of human betaine-homocysteine S-methyltransferase

Czech Academy of Sciences Publication Activity Database

Vaněk, Václav; Buděšínský, Miloš; Kabeleová, Petra; Šanda, Miloslav; Kožíšek, Milan; Hančlová, Ivona; Mládková, Jana; Brynda, Jiří; Rosenberg, Ivan; Koutmos, M.; Garrow, T. A.; Jiráček, Jiří

2009-01-01

Roč. 52, č. 12 (2009), s. 3652-3665 ISSN 0022-2623 R&D Projects: GA MŠk 1M0508 Grant - others:GA MŠk(CZ) LC06077; NIH(US) R01TW0052501 Program:LC Institutional research plan: CEZ:AV0Z40550506 Keywords : BHMT * betain * homocysteine * methionine * inhibitor Subject RIV: CE - Biochemistry Impact factor: 4.802, year: 2009
Bioavailability of D-methionine relative to L-methionine for nursery pigs using the slope-ratio assay

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Changsu Kong

2016-09-01

Full Text Available This experiment was conducted to determine the bioavailability of D-methionine (Met relative to L-Met for nursery pigs using the slope-ratio assay. A total of 50 crossbred barrows with an initial BW of 13.5 kg (SD = 1.0 were used in an N balance study. A Met-deficient basal diet (BD was formulated to contain an adequate amount of all amino acids (AA for 10–20 kg pigs except for Met. The two reference diets were prepared by supplementing the BD with 0.4 or 0.8 g L-Met/kg at the expense of corn starch, and an equivalent concentration of D-Met was added to the BD for the two test diets. The pigs were adapted to the experimental diets for 5 d and then total but separated collection of feces and urine was conducted for 4 d according to the marker-to-marker procedure. Nitrogen intakes were similar across the treatments. Fecal N output was not affected by Met supplementation regardless of source and consequently apparent N digestibility did not change. Conversely, there was a negative linear response (P < 0.01 to Met supplementation with both Met isomers in urinary N output, which resulted in increased retained N (g/4 d and N retention (% of intake. No quadratic response was observed in any of the N balance criteria. The estimated bioavailability of D-Met relative to L-Met from urinary N output (g/4 d and N retention (% of intake as dependent variables using supplemental Met intake (g/4 d as an independent variable were 87.6% and 89.6%, respectively; however, approximately 95% of the fiducial limits for the relative bioavailability estimates included 100%. In conclusion, with an absence of statistical significance, the present study indicated that the mean relative bioequivalence of D- to L-Met was 87.6% based on urinary N output or 89.6% based on N retention.
Evaluation glioma for C-11-methyl-L-methionine PET

International Nuclear Information System (INIS)

Kenji Torii; Joji Kawabe; Takehiro hayashi; Jin Kotani; Ai Oe; Etsushi Kawamura; Hirotaka Ishizu; Hiroyuki Tsushima; Mitsuhiro Hara; Susumu Shiomi; Naohiro Tsuyuguchi

2004-01-01

Positron emission tomography (PET) using a positron tracer allows noninvasive measurement of regional brain metabolism and has been utilized for pathophysiological evaluation of brain tumors and as a highly specific means for diagnosis of brain tumors. Like the images yielded from anatomical imaging techniques such as computer tomography (CT) and magnetic resonance imaging (MRI), PET images play an important role as functional images. In cases of glioma, the manner by which the tumor cells spread to surrounding cells varies from case to case, and the extent of their spread also varies among different cases. It is reported that glioma is difficult to detect on anatomical images. C-11-methyl-L-methionine (Met) is taken up into glioma more markedly than into intact tissue and is thus considered to provide a useful means of tumor localization. It is possible to precisely determine the scope of glioma invasion by CT, MRI or F-18 fluoro-2-deoxy-D-glucose (FDG)-PET. This information is useful in determining an optimal operative procedure, the scope of postoperative radiotherapy and an optimal chemotherapy individual cases. It is also known that the evaluation of the malignancy level of glioma is closely related to the prognosis of patients with this tumor. Although FDG-PET allows evaluation of the malignancy level of glioma, PET using methionine (Met-PET) provides the best means of localization of tumors (including determination of the extent of tumor invasion). Therefore, if a technique of evaluating the malignancy level of glioma using Met-PET is established, it will be highly useful in clinical practice. At our facility, attempts have been made to use FDG-PET and Met-PET for evaluation of the malignancy level and scope of invasion of tumors in patients suspected of having brain tumors. The present study was undertaken to evaluate the degree of accumulation of Met in glioma using Met-PET (a technique expected to allow more accurate evaluation of the extent of tumor
Specialized (iso)eugenol-4-O-methyltransferases (s-IEMTs) and methods of making and using the same

Science.gov (United States)

Liu, Chang-Jun; Cai, Yuanheng

2017-01-31

Specialized (iso)eugenol 4-O-methyltransferase (s-IEMT) enzymes having increased capacity for methylation of monolignols are disclosed. The s-IEMTs have unique activity favoring methylation of coniferyl alcohol versus sinapyl alcohol. Various s-IEMTs methylate ferulic acid. Means for producing the various s-IEMTs are provided. The s-IEMTs are useful for modification of lignin content and production of aromatic compounds.
Cloning, expression, crystallization and preliminary X-ray analysis of the XMT and DXMT N-methyltransferases from Coffea canephora (robusta)

Energy Technology Data Exchange (ETDEWEB)

McCarthy, Andrew A., E-mail: andrewmc@embl.fr [European Molecular Biology Laboratory, 6 Rue Jules Horowitz, BP 181, 38042 Grenoble (France); Biget, Laurent [Nestlé Research and Development, 101 Avenue Gustave Eiffel, Notre-Dame D’Oe, 37097 Tours (France); Lin, Chenwei [Department of Plant Breeding and Genetics, Department of Plant Biology, Cornell University, Ithaca, NY 14853 (United States); Petiard, Vincent [Nestlé Research and Development, 101 Avenue Gustave Eiffel, Notre-Dame D’Oe, 37097 Tours (France); Tanksley, Steve D. [Department of Plant Breeding and Genetics, Department of Plant Biology, Cornell University, Ithaca, NY 14853 (United States); McCarthy, James G. [Nestlé Research and Development, 101 Avenue Gustave Eiffel, Notre-Dame D’Oe, 37097 Tours (France); European Molecular Biology Laboratory, 6 Rue Jules Horowitz, BP 181, 38042 Grenoble (France)

2007-04-01

The genes encoding XMT and DXMT, the enzymes from Coffea canephora (robusta) that catalyse the three independent N-methyl transfer reactions in the caffeine-biosynthesis pathway, have been cloned and the proteins have been expressed in Escherichia coli. Both proteins have been crystallized in the presence of the demethylated cofactor S-adenosyl-l-cysteine (SAH) and substrate (xanthosine for XMT and theobromine for DXMT). Caffeine is a secondary metabolite produced by a variety of plants including Coffea canephora (robusta) and there is growing evidence that caffeine is part of a chemical defence strategy protecting young leaves and seeds from potential predators. The genes encoding XMT and DXMT, the enzymes from Coffea canephora (robusta) that catalyse the three independent N-methyl transfer reactions in the caffeine-biosynthesis pathway, have been cloned and the proteins have been expressed in Escherichia coli. Both proteins have been crystallized in the presence of the demethylated cofactor S-adenosyl-l-cysteine (SAH) and substrate (xanthosine for XMT and theobromine for DXMT). The crystals are orthorhombic, with space group P2{sub 1}2{sub 1}2{sub 1} for XMT and C222{sub 1} for DXMT. X-ray diffraction to 2.8 Å for XMT and to 2.5 Å for DXMT have been collected on beamline ID23-1 at the ESRF.
Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system.

Science.gov (United States)

Zhou, Lei; Zheng, Wei; Ji, Yuefei; Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi; Yang, Xi

2013-12-15

In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S2O8(2-) and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na2S2O3, diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na2) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na2S2O3 were found to be more effective than DTPA and EDTA-Na2. Our results also revealed a widely practical prospect of inorganic chelating agent Na2S2O3. Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed. Copyright © 2013 Elsevier B.V. All rights reserved.
YebU is a m5C methyltransferase specific for 16 S rRNA nucleotide 1407

DEFF Research Database (Denmark)

Andersen, Niels Møller; Douthwaite, Stephen

2006-01-01

generally require specific enzymes, and only one m5C rRNA methyltransferase, RsmB (formerly Fmu) that methylates nucleotide C967, has previously been identified. BLAST searches of the E.coli genome revealed a single gene, yebU, with sufficient similarity to rsmB to encode a putative m5C RNA...... methyltransferase. This suggested that the yebU gene product modifies C1407 and/or C1962. Here, we analysed the E.coli rRNAs by matrix assisted laser desorption/ionization mass spectrometry and show that inactivation of the yebU gene leads to loss of methylation at C1407 in 16 S rRNA, but does not interfere...
Measurement of the delta34S value in methionine by double spike multi-collector thermal ionization mass spectrometry using Carius tube digestion.

Science.gov (United States)

Mann, Jacqueline L; Kelly, W Robert

2010-09-15

Methionine is an essential amino acid and is the primary source of sulfur for humans. Using the double spike ((33)S-(36)S) multi-collector thermal ionization mass spectrometry (MC-TIMS) technique, three sample bottles of a methionine material obtained from the Institute for Reference Materials and Measurements have been measured for delta(34)S and sulfur concentration. The mean delta(34)S value, relative to Vienna Canyon Diablo Troilite (VCDT), determined was 10.34 +/- 0.11 per thousand (n = 9) with the uncertainty reported as expanded uncertainties (U). These delta(34)S measurements include a correction for blank which has been previously ignored in studies of sulfur isotopic composition. The sulfur concentrations for the three bottles range from 56 to 88 microg/g. The isotope composition and concentration results demonstrate the high accuracy and precision of the DS-MC-TIMS technique for measuring sulfur in methionine.
A SAM-dependent methyltransferase cotranscribed with arsenate reductase alters resistance to peptidyl transferase center-binding antibiotics in Azospirillum brasilense Sp7.

Science.gov (United States)

Singh, Sudhir; Singh, Chhaya; Tripathi, Anil Kumar

2014-05-01

The genome of Azospirillum brasilense harbors a gene encoding S-adenosylmethionine-dependent methyltransferase, which is located downstream of an arsenate reductase gene. Both genes are cotranscribed and translationally coupled. When they were cloned and expressed individually in an arsenate-sensitive strain of Escherichia coli, arsenate reductase conferred tolerance to arsenate; however, methyltransferase failed to do so. Sequence analysis revealed that methyltransferase was more closely related to a PrmB-type N5-glutamine methyltransferase than to the arsenate detoxifying methyltransferase ArsM. Insertional inactivation of prmB gene in A. brasilense resulted in an increased sensitivity to chloramphenicol and resistance to tiamulin and clindamycin, which are known to bind at the peptidyl transferase center (PTC) in the ribosome. These observations suggested that the inability of prmB:km mutant to methylate L3 protein might alter hydrophobicity in the antibiotic-binding pocket of the PTC, which might affect the binding of chloramphenicol, clindamycin, and tiamulin differentially. This is the first report showing the role of PrmB-type N5-glutamine methyltransferases in conferring resistance to tiamulin and clindamycin in any bacterium.

Identification of the RsmG methyltransferase target as 16S rRNA nucleotide G527 and characterization of Bacillus subtilis rsmG mutants

DEFF Research Database (Denmark)

Nishimura, Kenji; Johansen, Shanna K; Inaoka, Takashi

2007-01-01

The methyltransferase RsmG methylates the N7 position of nucleotide G535 in 16S rRNA of Bacillus subtilis (corresponding to G527 in Escherichia coli). Disruption of rsmG resulted in low-level resistance to streptomycin. A growth competition assay revealed that there are no differences in fitness...... between the rsmG mutant and parent strains under the various culture conditions examined. B. subtilis rsmG mutants emerged spontaneously at a relatively high frequency, 10(-6). Importantly, in the rsmG mutant background, high-level-streptomycin-resistant rpsL (encoding ribosomal protein S12) mutants...
Synthesis of high specific activity tritium labelled compounds

International Nuclear Information System (INIS)

Parent, P.

1986-01-01

Tritiated methyl iodide of high specific activity is synthetized by Fischer-Tropsch reaction of tritium with carbon monoxide, tritiated methanol obtained is reacted with hydriodic acid. It is used for the synthesis of S-adenosyl L-methionine 3 H-methyl and of diazepam 3 H-methyl derivatives. Synthesis of 3-PPP 3 H: (hydroxy-3 phenyl)-3N-n propyl [ 3 H-2.3] piperidine [ 3 H-2.3] with a specific activity of 4.25 T Bq/mM (115 Ci/mM) and of baclofene 3 H with a specific activity of 0.925 TBq (25 Ci/mM) are also described [fr
Combined Effect of the Cfr Methyltransferase and Ribosomal Protein L3 Mutations on Resistance to Ribosome-Targeting Antibiotics.

Science.gov (United States)

Pakula, Kevin K; Hansen, Lykke H; Vester, Birte

2017-09-01

Several groups of antibiotics inhibit bacterial growth by binding to bacterial ribosomes. Mutations in ribosomal protein L3 have been associated with resistance to linezolid and tiamulin, which both bind at the peptidyl transferase center in the ribosome. Resistance to these and other antibiotics also occurs through methylation of 23S rRNA at position A2503 by the methyltransferase Cfr. The mutations in L3 and the cfr gene have been found together in clinical isolates, raising the question of whether they have a combined effect on antibiotic resistance or growth. We transformed a plasmid-borne cfr gene into a uL3-depleted Escherichia coli strain containing either wild-type L3 or L3 with one of seven mutations, G147R, Q148F, N149S, N149D, N149R, Q150L, or T151P, expressed from plasmid-carried rplC genes. The L3 mutations are well tolerated, with small to moderate growth rate decreases. The presence of Cfr has a very minor influence on the growth rate. The resistance of the transformants to linezolid, tiamulin, florfenicol, and Synercid (a combination of quinupristin and dalfopristin [Q-D]) was measured by MIC assays. The resistance from Cfr was, in all cases, stronger than the effects of the L3 mutations, but various effects were obtained with the combinations of Cfr and L3 mutations ranging from a synergistic to an antagonistic effect. Linezolid and tiamulin susceptibility varied greatly among the L3 mutations, while no significant effects on florfenicol and Q-D susceptibility were seen. This study underscores the complex interplay between various resistance mechanisms and cross-resistance, even from antibiotics with overlapping binding sites. Copyright © 2017 American Society for Microbiology.
Insulin and adenosine regulate the phosphatidylcholine concentration in isolated rat adipocyte plasma membranes.

Science.gov (United States)

Kiechle, F L; Sykes, E; Artiss, J D

1995-01-01

Blockade of adenosine receptors by 3-isobutyl-1-methylxanthine or degradation of endogenous adenosine with adenosine deaminase increased the phosphatidylcholine concentration in isolated rat adipocyte plasma membranes, an effect which was suppressed by the phosphatidylethanolamine methyltransferase inhibitor, S-adenosyl-L-homocysteine, and reversed by the adenosine analogue, N6-(L-phenylisopropyl)-adenosine. For example, the addition of N6-(L-phenylisopropyl)-adenosine to adenosine deaminase pretreated plasma membranes rapidly lowered the concentration of phosphatidylcholine by 171 nmol/mg at 30 seconds compared to control. Insulin-induced stimulation of phospholipid methylation in membranes treated with 3-isobutyl-1-methylxanthine or adenosine deaminase was achieved only after the addition of N6-(L-phenylisopropyl)-adenosine. These results suggest that adenosine receptor occupancy inhibits phospholipid methylation, is required for insulin stimulation of phospholipid methylation, and may perhaps activate a phosphatidylcholine-specific phospholipase C or phospholipase D.
Genome-wide meta-analysis of homocysteine and methionine metabolism identifies five one carbon metabolism loci and a novel association of ALDH1L1 with ischemic stroke.

Directory of Open Access Journals (Sweden)

Stephen R Williams

2014-03-01

Full Text Available Circulating homocysteine levels (tHcy, a product of the folate one carbon metabolism pathway (FOCM through the demethylation of methionine, are heritable and are associated with an increased risk of common diseases such as stroke, cardiovascular disease (CVD, cancer and dementia. The FOCM is the sole source of de novo methyl group synthesis, impacting many biological and epigenetic pathways. However, the genetic determinants of elevated tHcy (hyperhomocysteinemia, dysregulation of methionine metabolism and the underlying biological processes remain unclear. We conducted independent genome-wide association studies and a meta-analysis of methionine metabolism, characterized by post-methionine load test tHcy, in 2,710 participants from the Framingham Heart Study (FHS and 2,100 participants from the Vitamin Intervention for Stroke Prevention (VISP clinical trial, and then examined the association of the identified loci with incident stroke in FHS. Five genes in the FOCM pathway (GNMT [p = 1.60 × 10(-63], CBS [p = 3.15 × 10(-26], CPS1 [p = 9.10 × 10(-13], ALDH1L1 [p = 7.3 × 10(-13] and PSPH [p = 1.17 × 10(-16] were strongly associated with the difference between pre- and post-methionine load test tHcy levels (ΔPOST. Of these, one variant in the ALDH1L1 locus, rs2364368, was associated with incident ischemic stroke. Promoter analyses reveal genetic and epigenetic differences that may explain a direct effect on GNMT transcription and a downstream affect on methionine metabolism. Additionally, a genetic-score consisting of the five significant loci explains 13% of the variance of ΔPOST in FHS and 6% of the variance in VISP. Association between variants in FOCM genes with ΔPOST suggest novel mechanisms that lead to differences in methionine metabolism, and possibly the epigenome, impacting disease risk. These data emphasize the importance of a concerted effort to understand regulators of one carbon metabolism as potential therapeutic targets.
In Salmonella enterica, the Gcn5-Related Acetyltransferase MddA (Formerly YncA) Acetylates Methionine Sulfoximine and Methionine Sulfone, Blocking Their Toxic Effects

Science.gov (United States)

Hentchel, Kristy L.

2014-01-01

Protein and small-molecule acylation reactions are widespread in nature. Many of the enzymes catalyzing acylation reactions belong to the Gcn5-related N-acetyltransferase (GNAT; PF00583) family, named after the yeast Gcn5 protein. The genome of Salmonella enterica serovar Typhimurium LT2 encodes 26 GNATs, 11 of which have no known physiological role. Here, we provide in vivo and in vitro evidence for the role of the MddA (methionine derivative detoxifier; formerly YncA) GNAT in the detoxification of oxidized forms of methionine, including methionine sulfoximine (MSX) and methionine sulfone (MSO). MSX and MSO inhibited the growth of an S. enterica ΔmddA strain unless glutamine or methionine was present in the medium. We used an in vitro spectrophotometric assay and mass spectrometry to show that MddA acetylated MSX and MSO. An mddA+ strain displayed biphasic growth kinetics in the presence of MSX and glutamine. Deletion of two amino acid transporters (GlnHPQ and MetNIQ) in a ΔmddA strain restored growth in the presence of MSX. Notably, MSO was transported by GlnHPQ but not by MetNIQ. In summary, MddA is the mechanism used by S. enterica to respond to oxidized forms of methionine, which MddA detoxifies by acetyl coenzyme A-dependent acetylation. PMID:25368301
Insights into the structure, function and evolution of the radical-SAM 23S rRNA methyltransferase Cfr that confers antibiotic resistance in bacteria

DEFF Research Database (Denmark)

Karminska, K. H.; Purta, E.; Hansen, L .H.

2010-01-01

The Cfr methyltransferase confers combined resistance to five classes of antibiotics that bind to the peptidyl tranferase center of bacterial ribosomes by catalyzing methylation of the C-8 position of 23S rRNA nucleotide A2503. The same nucleotide is targeted by the housekeeping methyltransferase...
YgdE is the 2'-O-ribose methyltransferase RlmM specific for nucleotide C2498 in bacterial 23S rRNA

DEFF Research Database (Denmark)

Purta, Elzbieta; O'Connor, Michelle; Bujnicki, Janusz M

2009-01-01

The rRNAs of Escherichia coli contain four 2'-O-methylated nucleotides. Similar to other bacterial species and in contrast with Archaea and Eukaryota, the E. coli rRNA modifications are catalysed by specific methyltransferases that find their nucleotide targets without being guided by small...... complementary RNAs. We show here that the ygdE gene encodes the methyltransferase that catalyses 2'-O-methylation at nucleotide C2498 in the peptidyl transferase loop of E. coli 23S rRNA. Analyses of rRNAs using MALDI mass spectrometry showed that inactivation of the ygdE gene leads to loss of methylation...... at nucleotide C2498. The loss of ygdE function causes a slight reduction in bacterial fitness. Methylation at C2498 was restored by complementing the knock-out strain with a recombinant copy of ygdE. The recombinant YgdE methyltransferase modifies C2498 in naked 23S rRNA, but not in assembled 50S subunits...
S-methylmethionine conversion to dimethylsulfoniopropionate: evidence for an unusual transamination reaction

International Nuclear Information System (INIS)

Rhodes, D.; Gage, D.A.; Cooper, A.J.L.; Hanson, A.D.

1997-01-01

Leaves of Wollastonia biflora (L.) DC. synthesize the osmoprotectant 3-dimethylsulfoniopropionate (DMSP) from methionine via S-methylmethionine (SMM) and 3-dimethylsulfoniopropionaldehyde (DMSP-ald); no other intermediates have been detected. To test whether the amino group of SMM is lost by transamination or deamination, [methyl-2H3, 15N]SMM was supplied to leaf discs, and 15N-labeling of amino acids was monitored, along with synthesis of [2H3]DMSP. After short incubations more 15N was incorporated into glutamate than into other amino acids, and the 15N abundance in glutamate exceeded that in the amide group of glutamine (Gln). This is more consistent with transamination than deamination, because deamination would be predicted to give greater labeling of Gln amide N due to reassimilation, via Gln synthetase, of the 15NH4+ released. This prediction was borne out by control experiments with 15NH4Cl. The transamination product of SMM, 4-dimethylsulfonio-2-oxobutyrate (DMSOB), is expected to be extremely unstable. This was confirmed by attempting to synthesize it enzymatically from SMM using L-amino acid oxidase or Gln transaminase K and from 4-methylthio-2-oxobutyrate using methionine S-methyltransferase. In each case, the reaction product decomposed rapidly, releasing dimethylsulfide. The conversion of SMM to DMSP-ald is therefore unlikely to involve a simple transamination that generates free DMSOB. Plausible alternatives are that DMSOB is channeled within a specialized transaminase-decarboxylase complex or that it exists only as the bound intermediate of a single enzyme catalyzing an unusual transamination-decarboxylation reaction
Quantitative autoradiographic investigations on hairs, skin, and nails with the precursors 35S-cystine or 35S-methionine and 3H-thymidine respectively in animal experiments

International Nuclear Information System (INIS)

Schmiegelow, P.; Berndt, G.; Lindner, J.; Puschmann, M.

1981-01-01

By quantitative autoradiographic methods we tested the possible influence of the sulphurous amino acid L-cystine on the growth of hair, skin and nails. In the 3 H-thymidine autoradiographic method the tracing index (percentage of traced cell cores in relation to the total number of cell cores of a cell population) is calculated morphologically. In the 35 S-cystine and the 35 S-methionine autoradiography a quantification is carried out by applying the microscopic photometer for the investigation of defined hair root cross-sections. Measured values are indicated which depend on dosage and on the incorporation time. The investigation of other agents provoking negative or positive reactions of the hair growth by means of this method will have to be realized. Unlabelled L-cystine seems to promote the growth of hairs, epidermic basal cells and of germ cells of mouse nails, according to experiences made in animal experiments. The latter findings will have to be completed and confirmed by additional experiments. (orig.) [de
Molecular cloning and characterization of l-methionine γ-lyase from Streptomyces avermitilis.

Science.gov (United States)

Kudou, Daizou; Yasuda, Eri; Hirai, Yoshiyuki; Tamura, Takashi; Inagaki, Kenji

2015-10-01

A pyridoxal 5'-phosphate-dependent methionine γ-lyase (MGL) was cloned from Streptomyces avermitilis catalyzed the degradation of methionine to α-ketobutyrate, methanethiol, and ammonia. The sav7062 gene (1,242 bp) was corresponded to 413 amino acid residues with a molecular mass of 42,994 Da. The deduced amino acid sequence showed a high degree of similarity to those of other MGL enzymes. The sav7062 gene was overexpressed in Escherichia coli. The enzyme was purified to homogeneity and exhibited the MGL catalytic activities. We cloned the enzyme that has the MGL activity in Streptomyces for the first time. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
[11C] Methionine as PET radiopharmaceutical produced at CDTN/CNEN

International Nuclear Information System (INIS)

Silveira, Marina B.; Ferreira, Soraya Z.; Carvalho, Tiago F.; Silva, Juliana B. da

2013-01-01

Carbon-11 ( 11 C) is an attractive radionuclide used in positron emission tomography (PET) since carbon is a ubiquitous element in biomolecules. Positron emitter-labeled amino acids are being widely used as indicators of tumor activity due to enhanced expression of amino acid transporter systems in cancer cells. L-[Methyl-( 11 C)] Methionine or [ 11 C]Methionine is being used in neuro-oncology and, unlike 2-[ 18 F]fluoro-2-deoxy-D-glucose ( 18 FDG), gives more contrast images and improves brain tumor diagnosis. The aim of this work was to develop the synthesis and quality control of [ 11 C]Methionine at the Radiopharmaceuticals Research and Production Facility (UPPR) of CDTN/CNEN. The synthesis of [ 11 C] Methionine was performed using two Sep-Pak tC18 plus cartridges one as solid support for the 11 C-methylation of the precursor L-homocysteine thiolactone hydrochloride and another for purification. The pH, radionuclidic identity and purity, residual solvents, radiochemical and chemical purity of the final product were evaluated as described on the European Pharmacopoeia 7.0 monograph. Total synthesis time was 18 minutes, the radiochemical yield was approximately 15% (non-decay corrected) and radiochemical purity was greater than 95%. [ 11 C]Methionine was successfully synthesized at CDTN using the described procedures and complied with quality requirements. Due to the rapid growth of oncologic PET scans in last decade, 11 C labelling holds great promises in the next few years with the application of other tracers beyond 18 FDG. This pioneering work of UPPR/CDTN represents a response to the demands of a growing nuclear medicine in the country focused on achieving better diagnostic imaging. (author)
A review of methionine dependency and the role of methionine restriction in cancer growth control and life-span extension.

Science.gov (United States)

Cavuoto, Paul; Fenech, Michael F

2012-10-01

Methionine is an essential amino acid with many key roles in mammalian metabolism such as protein synthesis, methylation of DNA and polyamine synthesis. Restriction of methionine may be an important strategy in cancer growth control particularly in cancers that exhibit dependence on methionine for survival and proliferation. Methionine dependence in cancer may be due to one or a combination of deletions, polymorphisms or alterations in expression of genes in the methionine de novo and salvage pathways. Cancer cells with these defects are unable to regenerate methionine via these pathways. Defects in the metabolism of folate may also contribute to the methionine dependence phenotype in cancer. Selective killing of methionine dependent cancer cells in co-culture with normal cells has been demonstrated using culture media deficient in methionine. Several animal studies utilizing a methionine restricted diet have reported inhibition of cancer growth and extension of a healthy life-span. In humans, vegan diets, which can be low in methionine, may prove to be a useful nutritional strategy in cancer growth control. The development of methioninase which depletes circulating levels of methionine may be another useful strategy in limiting cancer growth. The application of nutritional methionine restriction and methioninase in combination with chemotherapeutic regimens is the current focus of clinical studies. Copyright © 2012 Elsevier Ltd. All rights reserved.
Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system

International Nuclear Information System (INIS)

Zhou, Lei; Zheng, Wei; Ji, Yuefei; Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi; Yang, Xi

2013-01-01

Highlights: • Effective oxidation of As(III)/diuron is achieved by Fe(II)-activated persulfate. • Hydroxyl and sulfate radical play important roles in As(III) and diuron oxidation. • CA and Na 2 S 2 O 3 are efficient and environmental friendly chelating agents. • DFT calculation is found to be useful for degradation products prediction. -- Abstract: In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S 2 O 8 2− and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na 2 S 2 O 3 , diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na 2 ) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na 2 S 2 O 3 were found to be more effective than DTPA and EDTA-Na 2 . Our results also revealed a widely practical prospect of inorganic chelating agent Na 2 S 2 O 3 . Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed
Magnetic immunoassay using CdSe/ZnS quantum dots as fluorescent probes to detect the level of DNA methyltransferase 1 in human serum sample

Directory of Open Access Journals (Sweden)

Yu F

2018-01-01

Full Text Available Fei Yu,1,* Ya-min Xiong,1,* Song-cheng Yu,1 Lei-liang He,1 Shan-shan Niu,1 Yu-ming Wu,1 Jie Liu,1 Ling-bo Qu,2 Li-e Liu,1 Yong-jun Wu1 1College of Public Health, 2College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, Henan, People’s Republic of China *These authors contributed equally to this work Background: DNA methyltransferase 1 (DNMT1, a dominant enzyme responsible for the transfer of a methyl group from the universal methyl donor to the 5-position of cytosine residues in DNA, is essential for mammalian development and closely related to cancer and a variety of age-related chronic diseases. DNMT1 has become a useful biomarker in early disease diagnosis and a potential therapeutic target in cancer therapy and drug development. However, till now, most of the studies on DNA methyltransferase (MTase detection have focused on the prokaryote MTase and its activity.Methods: A magnetic fluorescence-linked immunosorbent assay (FLISA using CdSe/ZnS quantum dots as fluorescent probes was proposed for the rapid and sensitive detection of the DNMT1 level in this study. Key factors that affect the precision and accuracy of the determination of DNMT1 were optimized.Results: Under the optimal conditions, the limit of detection was 0.1 ng/mL, the linear range was 0.1–1,500 ng/mL, the recovery was 91.67%–106.50%, and the relative standard deviations of intra- and inter-assays were respectively 5.45%–11.29% and 7.03%–11.25%. The cross-reactivity rates with DNA methyltransferases 3a and 3b were only 4.0% and 9.4%, respectively. Furthermore, FLISA was successfully used to detect the levels of DNMT1 in human serum samples, and compared with commercial enzyme-linked immunosorbent assay (ELISA kits. The results revealed that there was a good correlation between FLISA and commercial ELISA kits (correlation coefficient r=0.866, p=0.001. The linear scope of FLISA was broader than ELISA, and the measurement time was much shorter
Measurement of methionine level with the LC-ESI-MS/MS method in schizophrenic patients.

Science.gov (United States)

Kulaksizoglu, S; Kulaksizoglu, B; Ellidag, H Y; Eren, E; Yilmaz, N; Baykal, A

2016-01-01

The purpose of this study was to evaluate plasma methionine levels by using liquid chromatography electrospray ionization-tandem mass spectroscopy (LC-ESI-MS/MS) in schizophrenic patients. A twelve-point standard graph was drawn, and the recovery rate, the intra-day and inter-day coefficients of variation (CV), the limit of detection (LOD), and the limit of quantification (LOQ) were evaluated. The y and R2 values of the standard graph equation were determined as 0.011x + 0.0179 and 0.9989, respectively, and the graph remained linear until the 200 µmol/l level. The intra-day coefficients of variation of the samples (n = 10) containing 8, 28, and 58 µmol/l methionine were determined as 2.68, 3.10, and 3.79%, respectively; while their inter-day coefficients of variation were determined as 2.98, 3.19, and 3.84%. The LOD and LOQ values were determined as 0.04 and 0.1 µmol/l, respectively, while the mean recovery rates were determined as 101.7 and 99.3%. Plasma methionine values were measured as 21.5 (19.5-24,6) µmol/l for the patient group, 17.8 (16.3-20.1) µmol/l for the control group, and the difference between the two groups was statistically significant (p = 0.03). LC-ESI-MS/MS method represents a fairly sensitive, economic, and rapid analysis that requires very little sample and is suitable for measuring methionine levels in schizophrenic patients.
Potential role of cysteine and methionine in the protection against hormonal imbalance and mutagenicity induced by furazolidone in female rats

International Nuclear Information System (INIS)

Ahmed, Hanaa H.; El-Aziem, Sekena H. Abd; Abdel-Wahhab, Mosaad A.

2008-01-01

The use of nitrofurans as veterinary drugs has been banned in the EU since 1993 due to doubts on the safety of the protein-bound residues of these drugs in edible products. Furazolidone (FUZ) is a nitrofuran drug, which has been used for many years as an antibacterial drug in veterinary practice. The aim of the current study is to investigate the role of L-cysteine and L-methionine in the protection against hormonal imbalance and the genotoxicity induced by FUZ using the micronucleus (MN) assay and random amplified polymorphism DNA (RAPD-PCR) analysis in female rats. Forty female Sprague-Dawley rats were divided into four groups included the untreated control group; a group treated with FUZ (300 mg/kg b.w.); a group treated with a mixture of L-cysteine (300 mg/kg b.w.) and L-methionine (42.8 mg/kg b.w.) and a group treated with FUZ plus the mixture of L-cysteine and L-methionine for 10 days. The results indicated that FUZ induced hormonal disturbances involving thyroid, ovarian and adrenal hormones. Moreover, FUZ increased the micronucleus formation and induced changes in polymorphic band patterns. The combined treatment with FUZ and the mixture of L-cysteine and L-methionine succeeded to prevent or diminish the endocrine disturbance and the clastogenic effects of FUZ. The current study is casting new light on the complex mechanisms underlying the ameliorating action of dietary L-cysteine and L-methionine against FUZ toxicity in experimental animals
Double-Headed Sulfur-Linked Amino Acids As First Inhibitors for Betaine-Homocysteine S-Methyltransferase 2

Czech Academy of Sciences Publication Activity Database

Mládková, Jana; Vaněk, Václav; Buděšínský, Miloš; Elbert, Tomáš; Demianova, Zuzana; Garrow, T. A.; Jiráček, Jiří

2012-01-01

Roč. 55, č. 15 (2012), s. 6822-6831 ISSN 0022-2623 R&D Projects: GA ČR GA203/09/1919; GA ČR(CZ) GAP207/10/1277 Institutional support: RVO:61388963 Keywords : betaine * homocysteine * methionine * BHMT * inhibitor Subject RIV: CE - Biochemistry Impact factor: 5.614, year: 2012
Mapping of sulfur metabolic pathway by LC Orbitrap mass spectrometry

International Nuclear Information System (INIS)

Rao Yulan; McCooeye, Margaret; Mester, Zoltán

2012-01-01

Highlights: ► LCMS method for the determination of free, oxidized and protein bound thiols in yeast was developed. ► In freshly harvested yeast, most of the thiols were in the reduced forms. ► The stress response of yeast to H 2 O 2 , Cd and As was studied via changes in the thiol profiles. - Abstract: For the first time a liquid chromatography method with high resolution mass spectrometric detection has been developed for the simultaneous determination all key metabolites of the sulfur pathway in yeast, including all thiolic (cysteine (Cys), homocysteine (HCys), glutathione (GSH), cysteinyl-glycine (Cys-Gly), γ-glutamyl-cysteine (Glu-Cys)) and non-thiolic compounds (methionine (Met), s-adenosyl-methionine (AdoMet), s-adenosyl-homocysteine (AdoHcy), and cystathionine (Cysta)). The developed assay also permits the speciation and selective determination of reduced, oxidized and protein bound fractions of all of the five thiols. Iodoacetic acid (IAA) was chosen as the derivatizing reagent. Thiols were extracted from sub-mg quantities of yeast using hot 75% ethanol. The detection limits were in the range of 1–12 nmol L −1 for standard solution (high femotomole, absolute), except AdoMet (116 nmol L −1 ), which was unstable. In freshly harvested yeast, most of the thiols were in the reduced forms and low levels of protein-bound GSH and Glu-Cys were found. In a selenium enriched yeast, the thiols were mainly in the oxidized forms, and a significant amount of protein-bound Cys, HCys, GSH, Cys-Gly and Glu-Cys were found. The method was also applied to the metabolic study of the adaptive response of Saccharomyces cerevisiae to hydrogen peroxide, cadmium, and arsenite, and the change in concentration of thiols in the sulfur pathway was monitored over a period of 4 h.
Mapping of sulfur metabolic pathway by LC Orbitrap mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Rao Yulan [Institute for National Measurement Standard, National Research Council Canada, Ottawa, Ontario K1A 0R6 (Canada); Department of Forensic Medicine, Shanghai Medical College, Fudan University, Shanghai 200032 (China); McCooeye, Margaret [Institute for National Measurement Standard, National Research Council Canada, Ottawa, Ontario K1A 0R6 (Canada); Mester, Zoltan, E-mail: zoltan.mester@nrc.ca [Institute for National Measurement Standard, National Research Council Canada, Ottawa, Ontario K1A 0R6 (Canada)

2012-04-06

Highlights: Black-Right-Pointing-Pointer LCMS method for the determination of free, oxidized and protein bound thiols in yeast was developed. Black-Right-Pointing-Pointer In freshly harvested yeast, most of the thiols were in the reduced forms. Black-Right-Pointing-Pointer The stress response of yeast to H{sub 2}O{sub 2}, Cd and As was studied via changes in the thiol profiles. - Abstract: For the first time a liquid chromatography method with high resolution mass spectrometric detection has been developed for the simultaneous determination all key metabolites of the sulfur pathway in yeast, including all thiolic (cysteine (Cys), homocysteine (HCys), glutathione (GSH), cysteinyl-glycine (Cys-Gly), {gamma}-glutamyl-cysteine (Glu-Cys)) and non-thiolic compounds (methionine (Met), s-adenosyl-methionine (AdoMet), s-adenosyl-homocysteine (AdoHcy), and cystathionine (Cysta)). The developed assay also permits the speciation and selective determination of reduced, oxidized and protein bound fractions of all of the five thiols. Iodoacetic acid (IAA) was chosen as the derivatizing reagent. Thiols were extracted from sub-mg quantities of yeast using hot 75% ethanol. The detection limits were in the range of 1-12 nmol L{sup -1} for standard solution (high femotomole, absolute), except AdoMet (116 nmol L{sup -1}), which was unstable. In freshly harvested yeast, most of the thiols were in the reduced forms and low levels of protein-bound GSH and Glu-Cys were found. In a selenium enriched yeast, the thiols were mainly in the oxidized forms, and a significant amount of protein-bound Cys, HCys, GSH, Cys-Gly and Glu-Cys were found. The method was also applied to the metabolic study of the adaptive response of Saccharomyces cerevisiae to hydrogen peroxide, cadmium, and arsenite, and the change in concentration of thiols in the sulfur pathway was monitored over a period of 4 h.

1-13C; methyl-2H3 methionine kinetics in humans: Methionine conservation and cystine sparing

International Nuclear Information System (INIS)

Storch, K.J.; Wagner, D.A.; Burke, J.F.; Young, V.R.

1990-01-01

Methionine (Met) conservation in healthy young adult men (4/diet group) was explored by supplying one of the following three L-amino acid based diets: (1) adequate Met but no cystine; (2) neither Met nor cystine; or (3) no Met but cystine supplementation. After 5 days, subjects received a continuous intravenous infusion of L-[1-13C; methyl-2H3]Met for 5 h while the diet was given as small isocaloric isonitrogenous meals. Estimates were made of rates of Met incorporation into protein synthesis (S) and release from body proteins (B), transmethylation (TM), remethylation of homocysteine (RM), and transsulfuration (TS). For the adequate Met diet, the rates were S = 24 +/- 2, B = 18 +/- 1, TM = 12.4 +/- 1.7, RM = 4.7 +/- 1.1, and TS = 7.6 +/- 0.6 (SE) mumol.kg-1.h-1. The sulfur amino acid-devoid diet significantly (P less than 0.05) reduced S, TM, RM, and TS. Supplementation of this diet with cystine reduced Met oxidation (P = 0.05). Therefore, two loci are quantitatively important regulatory points in Met conservation in vivo: (1) the distribution of Met between the pathways of protein anabolism and TM (Met locus) and (2) the distribution of homocysteine between RM and TS (homocysteine locus)
Effect of different levels of lysine in the diet of broilers on the metabolism of /sup 35/S-methionine

Energy Technology Data Exchange (ETDEWEB)

Stanchev, Kh; Venkov, T; Dzharova, M [Akademiya na Selskostopanskite Nauki, Sofia-Kostinbrod (Bulgaria). Inst. po Zhivotnovydstvo

1974-01-01

The lack of balance of the ration with respect to lysine leads to a decrease in the rate of incorporation of /sup 35/S-methionine in the liver, pancreas, kidney and femoral muscle. Most intensive protein synthesis in the liver of chickens is observed in the group receiving ration balanced with respect to lysine while in the case of a deficiency or excess of lysine the protein biosynthesis drops. The deficiency or excess of lysine leads to an increase in the excretion rate and decreases the assimilability of radioactive methionine in the chickens organisms. (INIS)
Method development for the determination of arsenic by sequential injection/anodic stripping voltammetry using long-lasting gold-modified screen-printed carbon electrode.

Science.gov (United States)

Punrat, Eakkasit; Chuanuwatanakul, Suchada; Kaneta, Takashi; Motomizu, Shoji; Chailapakul, Orawon

2013-11-15

An automated method has been developed for determining the concentration of inorganic arsenic. The technique uses sequential injection/anodic stripping voltammetry with a long-lasting gold-modified screen-printed carbon electrode. The long-lasting gold electrode was electrochemically deposited onto a screen-printed carbon electrode at a potential of -0.5 V vs. Ag/AgCl in a supporting electrolyte solution of 1M hydrochloric acid. Under optimal conditions and the applied potentials, the electrode demonstrated that it can be used for a long time without a renewal process. The linear range for the determination of arsenic(III) was 1-100 μg L(-1), and the limit of detection (LOD) in standard solutions was as low as 0.03 μg L(-1) for a deposition time of 120 s and sample volume of 1 mL. This method was used to determine the concentration of arsenic(III) in water samples with satisfactory results. The LOD in real samples was found to be 0.5 μg L(-1). In addition, speciation between arsenic(III) and arsenic(V) has been achieved with the proposed method using deposition potentials of -0.5 V and -1.5 V for the determination of the arsenic(III) concentration and the total arsenic concentration, respectively; the results were acceptable. The proposed method is an automated system that offers a less expensive alternative for determining trace amounts of inorganic arsenic. © 2013 Elsevier B.V. All rights reserved.
[11C] Methionine as PET radiopharmaceutical produced at CDTN/CNEN

Energy Technology Data Exchange (ETDEWEB)

Silveira, Marina B.; Ferreira, Soraya Z.; Carvalho, Tiago F.; Silva, Juliana B. da, E-mail: mbs@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Unidade de Pesquisa e Producao de Radiofarmacos

2013-07-01

Carbon-11 ({sup 11}C) is an attractive radionuclide used in positron emission tomography (PET) since carbon is a ubiquitous element in biomolecules. Positron emitter-labeled amino acids are being widely used as indicators of tumor activity due to enhanced expression of amino acid transporter systems in cancer cells. L-[Methyl-({sup 11}C)] Methionine or [{sup 11}C]Methionine is being used in neuro-oncology and, unlike 2-[{sup 18}F]fluoro-2-deoxy-D-glucose ({sup 18}FDG), gives more contrast images and improves brain tumor diagnosis. The aim of this work was to develop the synthesis and quality control of [{sup 11}C]Methionine at the Radiopharmaceuticals Research and Production Facility (UPPR) of CDTN/CNEN. The synthesis of [{sup 11}C] Methionine was performed using two Sep-Pak tC18 plus cartridges one as solid support for the {sup 11}C-methylation of the precursor L-homocysteine thiolactone hydrochloride and another for purification. The pH, radionuclidic identity and purity, residual solvents, radiochemical and chemical purity of the final product were evaluated as described on the European Pharmacopoeia 7.0 monograph. Total synthesis time was 18 minutes, the radiochemical yield was approximately 15% (non-decay corrected) and radiochemical purity was greater than 95%. [{sup 11}C]Methionine was successfully synthesized at CDTN using the described procedures and complied with quality requirements. Due to the rapid growth of oncologic PET scans in last decade, {sup 11}C labelling holds great promises in the next few years with the application of other tracers beyond {sup 18}FDG. This pioneering work of UPPR/CDTN represents a response to the demands of a growing nuclear medicine in the country focused on achieving better diagnostic imaging. (author)
Mutagenic and cytotoxic properties of 6-thioguanine, S6-methylthioguanine, and guanine-S6-sulfonic acid.

Science.gov (United States)

Yuan, Bifeng; Wang, Yinsheng

2008-08-29

Thiopurine drugs, including 6-thioguanine ((S)G), 6-mercaptopurine, and azathioprine, are widely employed anticancer agents and immunosuppressants. The formation of (S)G nucleotides from the thiopurine prodrugs and their subsequent incorporation into nucleic acids are important for the drugs to exert their cytotoxic effects. (S)G in DNA can be methylated by S-adenosyl-l-methionine to give S(6)-methylthioguanine (S(6)mG) and oxidized by UVA light to render guanine-S(6)-sulfonic acid ((SO3H)G). Here, we constructed single-stranded M13 shuttle vectors carrying a (S)G, S(6)mG, or (SO3H)G at a unique site and allowed the vectors to propagate in wild-type and bypass polymerase-deficient Escherichia coli cells. Analysis of the replication products by using the competitive replication and adduct bypass and a slightly modified restriction enzyme digestion and post-labeling assays revealed that, although none of the three thionucleosides considerably blocked DNA replication in all transfected E. coli cells, both S(6)mG and (SO3H)G were highly mutagenic, which resulted in G-->A mutation at frequencies of 94 and 77%, respectively, in wild-type E. coli cells. Deficiency in bypass polymerases does not result in alteration of mutation frequencies of these two lesions. In contrast to what was found from previous steady-state kinetic analysis, our data demonstrated that 6-thioguanine is mutagenic, with G-->A transition occurring at a frequency of approximately 10%. The mutagenic properties of 6-thioguanine and its derivatives revealed in the present study offered important knowledge about the biological implications of these thionucleosides.
Expression of a methionine-rich storage albumin from the Brazil nut (Bertholletia excelsa H.B.K., Lecythidaceae in transgenic bean plants (Phaseolus vulgaris L., Fabaceae

Directory of Open Access Journals (Sweden)

Aragão F.J.L.

1999-01-01

Full Text Available Bean (Phaseolus vulgaris, an important component in the diet of people in developing countries, has low levels of the essential amino acid, methionine. We have attempted to correct this deficiency by introducing a transgene coding for a methionine-rich storage albumin from the Brazil nut via biolistic methods. The transgene's coding sequence was driven by a doubled 35S CaMV promoter and AMV enhancer sequences. The transgene was stable and correctly expressed in homozygous R2 to R5 seeds. In two of the five transgenic lines the methionine content was significantly increased (14 and 23% over the values found in untransformed plants.
Effect of methionine and cysteine deprivation on growth of different natural isolates of Lactobacillus spp. in chemically defined media

Directory of Open Access Journals (Sweden)

Lozo Jelena

2008-01-01

Full Text Available The purpose of this study was to determine the ability of natural isolates of lactobacilli from different ecological niches to grow in a chemically defined medium in the presence or absence of sulphur-containing amino acids, methionine and/or cysteine. The obtained results indicate that cysteine is essential for growth of L. paracasei subsp. paracasei BGHN14 and BGSJ2-8, while methionine is essential for isolates BGHN40, BGCG31, and BGHV54T of the species L. plantarum. Methionine is also essential for growth of L. rhamnosus BGHV58T. Other analyzed strains, such as L. plantarum BGSJ3-18, BGZB19, BGHV52Ta, and BGHV43T, require the presence of both amino acids for their growth.
Oxidation of protein tyrosine or methionine residues: From the amino acid to the peptide

Energy Technology Data Exchange (ETDEWEB)

Berges, J [Universite Pierre et Marie Curie, UMR 7616, Laboratoire de Chimie Theorique, 75005 Paris (France); Trouillas, P [EA 4021 Faculte de Pharmacie, 2 Rue du Dr. Marcland, 87025 Limoges Cedex (France); Houee-Levin, C, E-mail: jb@lct.jussieu.fr, E-mail: patrick.trouillas@unilim.fr, E-mail: chantal.houee@u-psud.fr [Universite Paris Sud, UMR 8000, Laboratoire de Chimie Physique, 91405 Orsay (France) (France)

2011-01-01

Methionine and tyrosine are competing targets of oxidizing free radicals in peptides or proteins. The first step is the addition of OH radicals either on the sulphur atom of methionine, followed by OH{sup -} elimination, or on the aromatic cycle of tyrosine. The next step can be stabilization of methionine radical cation by a two centre-three electron bond, or intramolecular electron transfer from tyrosine to the methionine radical cation. In this latter case a tyrosine radical is formed, which appears deprotonated. In a first step we have compared the stability of the OH radical adducts on Methionine or on Tyrosine. In agreement with experimental results, the thermodynamical data indicate that the OH adduct on Tyrosine and the radical cation are more stable than those on methionine. In a second step we have investigated the stabilization of the radical cations of Methionine by formation of intramolecular S:X two-center three-electron bond (X=S, N, O). Finally we have compared the spin densities on separated amino acids to that in a radical pentapeptide, methionine enkephalin. One observes a delocalisation of the orbital of the odd electron on the sulfur atom of Met and on the cycle of Tyr. The peptidic chain is also concerned.
Oxidation of protein tyrosine or methionine residues: From the amino acid to the peptide

International Nuclear Information System (INIS)

Berges, J; Trouillas, P; Houee-Levin, C

2011-01-01

Methionine and tyrosine are competing targets of oxidizing free radicals in peptides or proteins. The first step is the addition of OH radicals either on the sulphur atom of methionine, followed by OH - elimination, or on the aromatic cycle of tyrosine. The next step can be stabilization of methionine radical cation by a two centre-three electron bond, or intramolecular electron transfer from tyrosine to the methionine radical cation. In this latter case a tyrosine radical is formed, which appears deprotonated. In a first step we have compared the stability of the OH radical adducts on Methionine or on Tyrosine. In agreement with experimental results, the thermodynamical data indicate that the OH adduct on Tyrosine and the radical cation are more stable than those on methionine. In a second step we have investigated the stabilization of the radical cations of Methionine by formation of intramolecular S:X two-center three-electron bond (X=S, N, O). Finally we have compared the spin densities on separated amino acids to that in a radical pentapeptide, methionine enkephalin. One observes a delocalisation of the orbital of the odd electron on the sulfur atom of Met and on the cycle of Tyr. The peptidic chain is also concerned.
Post-translational modification of ribosomally synthesized peptides by a radical SAM epimerase in Bacillus subtilis

Science.gov (United States)

Benjdia, Alhosna; Guillot, Alain; Ruffié, Pauline; Leprince, Jérôme; Berteau, Olivier

2017-07-01

Ribosomally synthesized peptides are built out of L-amino acids, whereas D-amino acids are generally the hallmark of non-ribosomal synthetic processes. Here we show that the model bacterium Bacillus subtilis is able to produce a novel type of ribosomally synthesized and post-translationally modified peptide that contains D-amino acids, and which we propose to call epipeptides. We demonstrate that a two [4Fe-4S]-cluster radical S-adenosyl-L-methionine (SAM) enzyme converts L-amino acids into their D-counterparts by catalysing Cα-hydrogen-atom abstraction and using a critical cysteine residue as the hydrogen-atom donor. Unexpectedly, these D-amino acid residues proved to be essential for the activity of a peptide that induces the expression of LiaRS, a major component of the bacterial cell envelope stress-response system. Present in B. subtilis and in several members of the human microbiome, these epipeptides and radical SAM epimerases broaden the landscape of peptidyl structures accessible to living organisms.
Paradoxical elevated thiopurine S-methyltransferase activity after pancytopenia during azathioprine therapy: potential influence of red blood cell age

NARCIS (Netherlands)

de Boer, Nanne K. H.; van Bodegraven, Adriaan A.; de Graaf, Peer; van der Hulst, Rene W. M.; Zoetekouw, Lida; van Kuilenburg, André B. P.

2008-01-01

There is an increased risk of developing bone marrow depression and infections during azathioprine therapy for inflammatory bowel disease. Patients with low or absent thiopurine S-methyltransferase (TPMT) activity have an increased risk of developing myelotoxicity. We describe a patient who
Utilization of supplemental methionine sources by primary cultures of chick hepatocytes

International Nuclear Information System (INIS)

Dibner, J.J.

1983-01-01

Utilization of 2-hydroxy-4-(methylthio) butanoic acid (HMB) as a substrate for protein synthesis was studied by using primary cultures of chick liver cells. Cultures were prepared by enzymatic dissociation of livers from week old Hubbard broiler chicks and were maintained for 4 days under nonproliferative conditions. Hepatocyte differentiation was verified by using dexamethasone induction of tyrosine aminotransferase activity. Conversion of [14C]HMB to L-methionine was shown by chromatographic analysis of hepatocyte protein hydrolysate and incorporation into protein was proven by cycloheximide inhibition of synthesis. When incorporation of HMB was compared to that of DL-methionine (DLM) equimolar quantities of the two sources were found in liver cell protein. These results support, at a cellular level, the conclusion that HMB and DLM are biochemically equivalent sources of methionine for protein synthesis
Cobalamin-Independent Methionine Synthase (MetE): A Face-to-Face Double Barrel that Evolved by Gene Duplication

Energy Technology Data Exchange (ETDEWEB)

Pejcha, Robert; Ludwig, Martha L. (Michigan)

2010-03-08

Cobalamin-independent methionine synthase (MetE) catalyzes the transfer of a methyl group from methyltetrahydrofolate to L-homocysteine (Hcy) without using an intermediate methyl carrier. Although MetE displays no detectable sequence homology with cobalamin-dependent methionine synthase (MetH), both enzymes require zinc for activation and binding of Hcy. Crystallographic analyses of MetE from T. maritima reveal an unusual dual-barrel structure in which the active site lies between the tops of the two ({beta}{alpha}){sub 8} barrels. The fold of the N-terminal barrel confirms that it has evolved from the C-terminal polypeptide by gene duplication; comparisons of the barrels provide an intriguing example of homologous domain evolution in which binding sites are obliterated. The C-terminal barrel incorporates the zinc ion that binds and activates Hcy. The zinc-binding site in MetE is distinguished from the (Cys){sub 3}Zn site in the related enzymes, MetH and betaine-homocysteine methyltransferase, by its position in the barrel and by the metal ligands, which are histidine, cysteine, glutamate, and cysteine in the resting form of MetE. Hcy associates at the face of the metal opposite glutamate, which moves away from the zinc in the binary E {center_dot} Hcy complex. The folate substrate is not intimately associated with the N-terminal barrel; instead, elements from both barrels contribute binding determinants in a binary complex in which the folate substrate is incorrectly oriented for methyl transfer. Atypical locations of the Hcy and folate sites in the C-terminal barrel presumably permit direct interaction of the substrates in a ternary complex. Structures of the binary substrate complexes imply that rearrangement of folate, perhaps accompanied by domain rearrangement, must occur before formation of a ternary complex that is competent for methyl transfer.
Cobalamin-Independent Methionine Synthase (MetE): A Face-to-Face Double Barrel that Evolved by Gene Duplication

International Nuclear Information System (INIS)

Pejcha, Robert; Ludwig, Martha L.

2005-01-01

Cobalamin-independent methionine synthase (MetE) catalyzes the transfer of a methyl group from methyltetrahydrofolate to L-homocysteine (Hcy) without using an intermediate methyl carrier. Although MetE displays no detectable sequence homology with cobalamin-dependent methionine synthase (MetH), both enzymes require zinc for activation and binding of Hcy. Crystallographic analyses of MetE from T. maritima reveal an unusual dual-barrel structure in which the active site lies between the tops of the two (βα) 8 barrels. The fold of the N-terminal barrel confirms that it has evolved from the C-terminal polypeptide by gene duplication; comparisons of the barrels provide an intriguing example of homologous domain evolution in which binding sites are obliterated. The C-terminal barrel incorporates the zinc ion that binds and activates Hcy. The zinc-binding site in MetE is distinguished from the (Cys) 3 Zn site in the related enzymes, MetH and betaine-homocysteine methyltransferase, by its position in the barrel and by the metal ligands, which are histidine, cysteine, glutamate, and cysteine in the resting form of MetE. Hcy associates at the face of the metal opposite glutamate, which moves away from the zinc in the binary E · Hcy complex. The folate substrate is not intimately associated with the N-terminal barrel; instead, elements from both barrels contribute binding determinants in a binary complex in which the folate substrate is incorrectly oriented for methyl transfer. Atypical locations of the Hcy and folate sites in the C-terminal barrel presumably permit direct interaction of the substrates in a ternary complex. Structures of the binary substrate complexes imply that rearrangement of folate, perhaps accompanied by domain rearrangement, must occur before formation of a ternary complex that is competent for methyl transfer.
Cobalamin-independent methionine synthase (MetE: a face-to-face double barrel that evolved by gene duplication.

Directory of Open Access Journals (Sweden)

Robert Pejchal

2005-02-01

Full Text Available Cobalamin-independent methionine synthase (MetE catalyzes the transfer of a methyl group from methyltetrahydrofolate to L-homocysteine (Hcy without using an intermediate methyl carrier. Although MetE displays no detectable sequence homology with cobalamin-dependent methionine synthase (MetH, both enzymes require zinc for activation and binding of Hcy. Crystallographic analyses of MetE from T. maritima reveal an unusual dual-barrel structure in which the active site lies between the tops of the two (betaalpha(8 barrels. The fold of the N-terminal barrel confirms that it has evolved from the C-terminal polypeptide by gene duplication; comparisons of the barrels provide an intriguing example of homologous domain evolution in which binding sites are obliterated. The C-terminal barrel incorporates the zinc ion that binds and activates Hcy. The zinc-binding site in MetE is distinguished from the (Cys(3Zn site in the related enzymes, MetH and betaine-homocysteine methyltransferase, by its position in the barrel and by the metal ligands, which are histidine, cysteine, glutamate, and cysteine in the resting form of MetE. Hcy associates at the face of the metal opposite glutamate, which moves away from the zinc in the binary E.Hcy complex. The folate substrate is not intimately associated with the N-terminal barrel; instead, elements from both barrels contribute binding determinants in a binary complex in which the folate substrate is incorrectly oriented for methyl transfer. Atypical locations of the Hcy and folate sites in the C-terminal barrel presumably permit direct interaction of the substrates in a ternary complex. Structures of the binary substrate complexes imply that rearrangement of folate, perhaps accompanied by domain rearrangement, must occur before formation of a ternary complex that is competent for methyl transfer.
Oxidation of methionine - is it limiting the diagnostic properties of 99mTc-labeled Exendin-4, a Glucagon-Like Peptide-1 receptor agonist?

Science.gov (United States)

Janota, Barbara; Karczmarczyk, Urszula; Laszuk, Ewa; Garnuszek, Piotr; Mikołajczak, Renata

2016-01-01

Preliminary clinical evaluation of 99mTc-EDDA/HYNIC-Met14-Exendin-4 showed that the complex offers new diagnostic possibilities for insulinoma and MTC. Exendin-4 contains methionine at position 14 in the amino acid chain, which may be oxidized to methionine sulfoxide and, from the pharmaceutical point of view, the oxidized moiety becomes an undesired impurity in the final radioactive preparation. Therefore, the aim of this study was to investigate the influence of commonly used methods to eliminate the effect of methionine oxidation in peptides, i.e. the replacement of methionine by norleucine (Nle) and the addition of L-methionine, on the in vitro stability and the biodistribution. 99mTc-EDDA/HYNIC-Met14-Exendin-4, 99mTc-EDDA/HYNIC-Nle14-Exendin-4, 99mTc-EDDA/HYNIC-Met14-Ex-endin-4 with the addition of L-methionine and an oxidized form of Exendin-4, i.e. 99mTc-EDDA/HYNIC-Met14(ox)-Exendin-4 were compared in vivo with 68Ga-NODAGA-Nle14-Exendin-4 in normal Wistar rats. The stability and lipophilicity were determined in vitro. Biodistribution studies confirmed the specific uptake of all tested complexes in the GLP-1 positive organs: lungs, pancreas and stomach. The uptake of 99mTc-EDDA/HYNIC-Met14-Exendin-4 with the addition of L-methionine and for 68Ga-NODAGA-Nle14-Exendin-4 at 1h p.i. was around 2-fold higher than that of 99mTc-EDDA/HYNIC-Met14-Exendin-4 and 99mTc-EDDA/HYNIC-Nle14-Exendin-4. Although the substitution of methionine by norleucine in the HYNIC-Exendin-4 did not result in improved bio-distribution, the use of L-methionine, as the excipient that inhibits the oxidation of methionine in the peptide chain resulted in higher lung/blood and stomach/blood uptake ratios. Our results confirmed that methionine at position 14 of amino acid chain of Exendin-4 plays an important role in the interaction with GLP-1 receptor positive tissue.
Factors influencing methionine toxicity in young bobwhite quail

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Serafin, J.A.

1981-01-01

Young Bobwhite quail (Colinus virginianus) were fed low and adequate protein purified diets with and without excess methionine to evaluate factors affecting methionine toxicity. Growth of quail fed an adequate protein (27%) diet, without supplemental glycine, was depressed by 1.75% and 2.25% excess methionine. Supplemental glycine (.3%) alleviated growth depression caused by 2.25% excess methionine. Quail fed 1.75% and 2.25% excess methionine developed signs of toxicity characterized by weakness, a lowered, outstretched neck when moving, and ataxia. In addition, quail would fall on their sides when disturbed and spin with their heads retracted. These conditions were transient in nature. Growth of quail fed a low protein (18.9%) diet was depressed by 1% and 1.5% excess methionine and DL-homocystine. Quail fed 1% and 1.5% excess methionine in this diet also developed signs of toxicity, the incidence of which was greater and the duration longer than occurred with quail fed adequate protein. Supplementing a low protein (20.15%) diet with .3% or .6% glycine or threonine or a combination of these amino acids did not alleviate growth depression caused by 1.5% excess methionine; however, 2% and 3% supplemental glycine were somewhat effective. Supplements of glycine (2%, 3%) and threonine (1%) completely reversed growth depression from 1% excess methionine but did not influence growth of controls, indicating that both amino acids counteract methionine toxicity. Both glycine and threonine alone improved growth by about the same extent in diets with 1% or 1.5% excess methionine; however, these amino acids alleviated less than 30% of the growth depression resulting from 1.5% excess methionine. The effectiveness of glycine in alleviating methionine toxicity in a low protein diet was decreased, and hemoglobin levels were depressed with 1.5% excess methionine compared to less amounts.
Differential uptake of [18F]FET and [3H]L-methionine in focal cortical ischemia

International Nuclear Information System (INIS)

Salber, Dagmar; Stoffels, Gabriele; Pauleit, Dirk; Reifenberger, Guido; Sabel, Michael; Shah, Nadim Jon; Hamacher, Kurt; Coenen, Heinz H.; Langen, Karl-Josef

2006-01-01

Amino acids such as [ 11 C-methyl]L-methionine are particularly useful in brain tumor diagnosis, but unspecific uptake (e.g., in cerebral ischemia) has been reported. O-(2-[ 18 F]fluoroethyl)-L-tyrosine ([ 18 F]FET) shows a clinical potential similar to that of L-methionine (MET) in brain tumor diagnosis but is applicable on a wider clinical scale. The aim of this study was to evaluate the uptake of [ 18 F]FET and [ 3 H]MET in focal cortical ischemia in rats by dual-tracer autoradiography. Methods: Focal cortical ischemia was induced in 25 CDF rats using the photothrombosis (PT) model. At different time points up to 6 weeks after the induction of PT, [ 18 F]FET and [ 3 H]MET were injected intravenously. Additionally, contrast-enhanced magnetic resonance imaging (MRI) was performed in 10 animals. One hour after tracer injection, brains were cut in coronal sections and evaluated by dual-tracer autoradiography. Lesion-to-brain (L/B) ratios were calculated by dividing the maximal uptake in the lesion by the mean uptake in the brain. An L/B ratio of >2.0 was considered indicative of pathological uptake. Histological slices were stained by cresyl violet and supplemented by immunostainings for glial fibrillary acidic protein (GFAP) and CD68 in selected cases. Results: A variably increased uptake of both tracers was observed in the PT lesion and its demarcation zone up to 7 days after PT for [ 18 F]FET and up to 6 weeks for [ 3 H]MET. The cutoff level of 2.0 was exceeded in 12/25 animals for [ 18 F]FET and in 18/25 animals for [ 3 H]MET. Focally increased tracer uptake matched contrast enhancement in MRI in 3/10 cases for [ 18 F]FET and in 5/10 cases for [ 3 H]MET. Immunohistochemical staining in lesions with differential uptake of [ 18 F]FET and [ 3 H]MET revealed that selective uptake of [ 18 F]FET was associated with GFAP-positive astrogliosis while selective [ 3 H]MET uptake correlated with CD68-positive macrophage infiltration. Conclusions: [ 18 F]FET, like [ 3 H
Regulation of homocysteine metabolism and methylation in human and mouse tissues

Science.gov (United States)

Chen, Natalie C.; Yang, Fan; Capecci, Louis M.; Gu, Ziyu; Schafer, Andrew I.; Durante, William; Yang, Xiao-Feng; Wang, Hong

2010-01-01

Hyperhomocysteinemia is an independent risk factor for cardiovascular disease. Homocysteine (Hcy) metabolism involves multiple enzymes; however, tissue Hcy metabolism and its relevance to methylation remain unknown. Here, we established gene expression profiles of 8 Hcy metabolic and 12 methylation enzymes in 20 human and 19 mouse tissues through bioinformatic analysis using expression sequence tag clone counts in tissue cDNA libraries. We analyzed correlations between gene expression, Hcy, S-adenosylhomocysteine (SAH), and S-adenosylmethionine (SAM) levels, and SAM/SAH ratios in mouse tissues. Hcy metabolic and methylation enzymes were classified into two types. The expression of Type 1 enzymes positively correlated with tissue Hcy and SAH levels. These include cystathionine β-synthase, cystathionine-γ-lyase, paraxonase 1, 5,10-methylenetetrahydrofolate reductase, betaine:homocysteine methyltransferase, methionine adenosyltransferase, phosphatidylethanolamine N-methyltransferases and glycine N-methyltransferase. Type 2 enzyme expressions correlate with neither tissue Hcy nor SAH levels. These include SAH hydrolase, methionyl-tRNA synthase, 5-methyltetrahydrofolate:Hcy methyltransferase, S-adenosylmethionine decarboxylase, DNA methyltransferase 1/3a, isoprenylcysteine carboxyl methyltransferases, and histone-lysine N-methyltransferase. SAH is the only Hcy metabolite significantly correlated with Hcy levels and methylation enzyme expression. We established equations expressing combined effects of methylation enzymes on tissue SAH, SAM, and SAM/SAH ratios. Our study is the first to provide panoramic tissue gene expression profiles and mathematical models of tissue methylation regulation.—Chen, N. C., Yang, F., Capecci, L. M., Gu, Z., Schafer, A. I., Durante, W., Yang, X.-F., Wang, H. Regulation of homocysteine metabolism and methylation in human and mouse tissues. PMID:20305127
Intrinsic resistance to aminoglycosides in Enterococcus faecium is conferred by the 16S rRNA m5C1404-specific methyltransferase EfmM

DEFF Research Database (Denmark)

Galimand, Marc; Schmitt, Emmanuelle; Panvert, Michel

2011-01-01

methyltransferase, as well as by the previously characterized aac(6')-Ii that encodes a 6'-N-aminoglycoside acetyltransferase. Inactivation of efmM in E. faecium increases susceptibility to the aminoglycosides kanamycin and tobramycin, and, conversely, expression of a recombinant version of efmM in Escherichia coli...... confers resistance to these drugs. The EfmM protein shows significant sequence similarity to E. coli RsmF (previously called YebU), which is a 5-methylcytidine (m(5)C) methyltransferase modifying 16S rRNA nucleotide C1407. The target for EfmM is shown by mass spectrometry to be a neighboring 16S r...

Efficacy of DL-methionine hydroxy analogue-free acid in comparison to DL-methionine in growing male white Pekin ducks.

Science.gov (United States)

Kluge, H; Gessner, D K; Herzog, E; Eder, K

2016-03-01

The present study was performed to assess the bioefficacy of DL-methionine hydroxy analogue-free acid (MHA) in comparison to DL-methionine (DLM) as sources of methionine for growing male white Pekin ducks in the first 3 wk of life. For this aim, 580 1-day-old male ducks were allocated into 12 treatment groups and received a basal diet that contained 0.29% of methionine, 0.34% of cysteine and 0.63% of total sulphur containing amino acids or the same diet supplemented with either DLM or MHA in amounts to supply 0.05, 0.10, 0.15, 0.20, and 0.25% of methionine equivalents. Ducks fed the control diet without methionine supplement had the lowest final body weights, daily body weight gains and feed intake among all groups. Supplementation of methionine improved final body weights and daily body weight gains in a dose dependent-manner. There was, however, no significant effect of the source of methionine on all of the performance responses. Evaluation of the data of daily body weight gains with an exponential model of regression revealed a nearly identical efficacy (slope of the curves) of both compounds for growth (DLM = 100%, MHA = 101%). According to the exponential model of regression, 95% of the maximum values of daily body weight gain were reached at methionine supplementary levels of 0.080% and 0.079% for DLM and MHA, respectively. Overall, the present study indicates that MHA and DLM have a similar efficacy as sources of methionine for growing ducks. It is moreover shown that dietary methionine concentrations of 0.37% are required to reach 95% of the maximum of daily body weight gains in ducks during the first 3 wk of life. © 2015 Poultry Science Association Inc.
Measurement of plasma histamine: description of an improved method and normal values

International Nuclear Information System (INIS)

Dyer, J.; Warren, K.; Merlin, S.; Metcalfe, D.D.; Kaliner, M.

1982-01-01

The single isotopic-enzymatic assay of histamine was modified to increase its sensitivity and to facilitate measurement of plasma histamine levels. The modification involved extracting 3 H-1-methylhistamine (generated by the enzyme N-methyltransferase acting on histamine in the presence of S-[methyl- 3 H]-adenosyl-L-methionine) into chloroform and isolating the 3 H-1-methylhistamine by thin-layer chromatography (TLC). The TLC was developed in acetone:ammonium hydroxide (95:10), and the methylhistamine spot (Rf . 0.50) was identified with an o-phthalaldehyde spray, scraped from the plate, and assayed in a scintillation counter. The assay in plasma demonstrated a linear relationship from 200 to 5000 pg histamine/ml. Plasma always had higher readings than buffer, and dialysis of plasma returned these values to the same level as buffer, suggesting that the baseline elevations might be attributable to histamine. However, all histamine standard curves were run in dialyzed plasma to negate any additional influences plasma might exert on the assay. The arithmetic mean (+/- SEM) in normal plasma histamine was 318.4 +/- 25 pg/ml (n . 51), and the geometric mean was 280 +/- 35 pg/ml. Plasma histamine was significantly elevated by infusion of histamine at 0.05 to 1.0 micrograms/kg/min or by cold immersion of the hand of a cold-urticaria patient. Therefore this modified isotopic-enzymatic assay of histamine is extremely sensitive, capable of measuring fluctuations in plasma histamine levels within the normal range, and potentially useful in analysis of the role histamine plays in human physiology
Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system

Energy Technology Data Exchange (ETDEWEB)

Zhou, Lei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Zheng, Wei [Jiangsu Product Quality Supervision and Inspection Research Institute, Nanjing 210007 (China); Ji, Yuefei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Université Lyon 1, UMR CNRS 5256, Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), 2 Avenue Albert Einstein, F-69626 Villeurbanne (France); Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Yang, Xi, E-mail: yangxi@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China)

2013-12-15

Highlights: • Effective oxidation of As(III)/diuron is achieved by Fe(II)-activated persulfate. • Hydroxyl and sulfate radical play important roles in As(III) and diuron oxidation. • CA and Na{sub 2}S{sub 2}O{sub 3} are efficient and environmental friendly chelating agents. • DFT calculation is found to be useful for degradation products prediction. -- Abstract: In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S{sub 2}O{sub 8}{sup 2−} and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na{sub 2}S{sub 2}O{sub 3}, diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na{sub 2}) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na{sub 2}S{sub 2}O{sub 3} were found to be more effective than DTPA and EDTA-Na{sub 2}. Our results also revealed a widely practical prospect of inorganic chelating agent Na{sub 2}S{sub 2}O{sub 3}. Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed.
The toxicity of arsenic(III), chromium(VI) and zinc to groundwater copepods.

Science.gov (United States)

Hose, G C; Symington, K; Lott, M J; Lategan, M J

2016-09-01

Groundwater ecosystems globally are threatened by anthropogenic contamination, yet there are few ecotoxicological data using obligate groundwater biota on which to base risk assessments. Copepods are found inhabiting aquifers of different geologies around the world and so are a useful taxon for use in ecotoxicological studies of groundwater. The aim of this study was to test the sensitivity of obligate groundwater copepods to metal contaminants (arsenic(III), chromium(VI) and zinc) in groundwater in static 96 h, 14 days and 28 days exposure tests. The copepods were variably sensitive to As, Cr and Zn, with Cr being the most toxic across all taxa. No taxon was consistently most sensitive and there was no apparent relationship between the hardness, pH and organic carbon concentration of the diluent water and the sensitivity of biota. As expected, toxicity increased with exposure period and we encourage the use of longer exposure periods in future toxicity tests with groundwater organisms to reflect the greater exposure periods likely to be associated with groundwater contamination.
Growth and characterization of an efficient new NLO single crystal L-phenylalanine D-methionine for frequency conversion and optoelectronic applications

Science.gov (United States)

Sangeetha, P.; Jayaprakash, P.; Nageshwari, M.; Rathika Thaya Kumari, C.; Sudha, S.; Prakash, M.; Vinitha, G.; Lydia Caroline, M.

2017-11-01

Optically active single crystals of L-phenylalanine D-methionine (LPDM) were grown by slow evaporation technique by co-crystallization of amino acids L-phenylalanine and D-methionine in water. The unit cell dimensions have been identified from single crystal X-ray diffraction technique. The existences of various hydrocarbyls were examined by FTIR and FT-Raman spectroscopy. The carbon and hydrogen environment of the grown crystals were analyzed by FT NMR spectrum. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 259 nm and there by optical band gap energy Eg is calculated to be 5.35 eV. The Urbach energy, extinction coefficient, reflectance were calculated from UV-absorption data. Further, the thermal stability and accurate melting point has been investigated by TG/DSC techniques. The Kurtz powder SHG was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. The dielectric behavior of the specimen has been determined for various temperatures (313 K, 333 K, 353 K, 373 K) at different frequencies. Fluorescence study and the time resolved decay calculation was also performed for the LPDM crystal. Optical nonlinear susceptibility was measured in LPDM and the real and imaginary part of χ3 was evaluated by Z-scan technique using open and closed apertures.
Development of miniature module for [11C] methionine synthesis

International Nuclear Information System (INIS)

Watanabe, Toshimitsu; Araya, Hiroshi; Ueno, Satoshi

2006-01-01

[ 18 F]FDG-PET has spread rapidly in the cancer diagnosis. On the other hand, [ 11 C]Methionine is paid attention as one of the PET drugs that may help cancer diagnosis by [ 18 F]FDG. Due to its short half-life, repeated preparations of [ 11 C] Methionine, two or three times a day, are generally required for the routine PET practice. Although the automatic synthesis devices for [ 11 C]Methionine were developed, it was difficult to supply [ 11 C]Methionine two times a day or more. We developed a methionine synthesis system that was able to supply [ 11 C]Methionine two times a day or more, and a new methionine synthesis unit. The new synthesis unit is able to synthesize [ 11 C]Methionine efficiently without HPLC preparation and evaporation in a short time. The new methionine synthesis unit and system are more useful for the routine synthesis of [ 11 C]Methionine. (author)
Technical Note: Methionine, a precursor of methane in living plants

Science.gov (United States)

Lenhart, K.; Althoff, F.; Greule, M.; Keppler, F.

2015-03-01

When terrestrial plants were identified as producers of the greenhouse gas methane, much discussion and debate ensued not only about their contribution to the global methane budget but also with regard to the validity of the observation itself. Although the phenomenon has now become more accepted for both living and dead plants, the mechanism of methane formation in living plants remains to be elucidated and its precursor compounds to be identified. We made use of stable isotope techniques to verify the in vivo formation of methane, and, in order to identify the carbon precursor, 13C positionally labeled organic compounds were employed. Here we show that the amino acid L-methionine acts as a methane precursor in living plants. Employing 13C-labeled methionine clearly identified the sulfur-bound methyl group of methionine as a carbon precursor of methane released from lavender (Lavandula angustifolia). Furthermore, when lavender plants were stressed physically, methane release rates and the stable carbon isotope values of the emitted methane greatly increased. Our results provide additional support that plants possess a mechanism for methane production and suggest that methionine might play an important role in the formation of methane in living plants, particularly under stress conditions.
The effects of enhanced methionine synthesis on amino acid and anthocyanin content of potato tubers

Directory of Open Access Journals (Sweden)

Bánfalvi Zsófia

2008-06-01

Full Text Available Abstract Background Potato is a staple food in the diet of the world's population and also being used as animal feed. Compared to other crops, however, potato tubers are relatively poor in the essential amino acid, methionine. Our aim was to increase the methionine content of tubers by co-expressing a gene involved in methionine synthesis with a gene encoding a methionine-rich storage protein in potato plants. Results In higher plants, cystathionine γ-synthase (CgS is the first enzyme specific to methionine biosynthesis. We attempted to increase the methionine content of tubers by expressing the deleted form of the Arabidopsis CgS (CgSΔ90, which is not regulated by methionine, in potato plants. To increase the incorporation of free methionine into a storage protein the CgSΔ90 was co-transformed with the methionine-rich 15-kD β-zein. Results demonstrated a 2- to 6-fold increase in the free methionine content and in the methionine content of the zein-containing protein fraction of the transgenic tubers. In addition, in line with higher methionine content, the amounts of soluble isoleucine and serine were also increased. However, all of the lines with high level of CgSΔ90 expression were phenotypically abnormal showing severe growth retardation, changes in leaf architecture and 40- to 60% reduction in tuber yield. Furthermore, the colour of the transgenic tubers was altered due to the reduced amounts of anthocyanin pigments. The mRNA levels of phenylalanine ammonia-lyase (PAL, the enzyme catalysing the first step of anthocyanin synthesis, were decreased. Conclusion Ectopic expression of CgSΔ90 increases the methionine content of tubers, however, results in phenotypic aberrations in potato. Co-expression of the 15-kD β-zein with CgSΔ90 results in elevation of protein-bound methionine content of tubers, but can not overcome the phenotypical changes caused by CgSΔ90 and can not significantly improve the nutritional value of tubers. The level
11C-L-methionine for evaluation of pancreatic exocrine function

International Nuclear Information System (INIS)

Syrota, A.; Dop-Ngassa, M.; Cerf, M.; Paraf, A.; Crouzel, M.; Ricard, S.

1981-01-01

Pancreatic uptake of 11 C labelled L-methionine, was measured in 58 patients using a scintillation camera. Time-activity-curves obtained in areas of interest selected over the pancreas in 25 normal subjects and in 14 alcoholic patients showed a plateau or slight increase of activity with time. In contrast, in 19 patients with chronic pancreatitis, an initial increase in radioactivity was followed by a decrease for 10 to 20 minutes and then by a plateau. The ratio of the height of the plateau at the 50th minute to the height of the peak was 0.74 +- 0.21 in these patients, whereas it was 0.96 +- 0.09 in the other subjects (p 11 C radioactivity and of amylase and bicarbonate in duodenal aspirate. The median amount of 11 C incorporated into protein at the 70th minute was 53% of total activity in the control group, 28% in alcoholic patients, and only 3% in chronic pancreatitis. The absence of a peak of radioactivity in the duodenal juice, and the existence of a correlation between total 11 C output and amylase output suggested that there was no release of protein in the duodenum in chronic pancreatitis, and that the peak observed by external detection could be due to amino acid back-diffusion from the pancreas into the blood. (author)
The Role of the Catechol-o-methyltransferase (COMT) Gene Val158Met in Aggressive Behavior, A Review of Genetic Studies

Science.gov (United States)

Qayyum, Arqam; Zai, Clement C.; Hirata, Yuko; Tiwari, Arun K.; Cheema, Sheraz; Nowrouzi, Behdin; Beitchman, Joseph H.; Kennedy, James L.

2015-01-01

Aggressive behaviors have become a major public health problem, and early-onset aggression can lead to outcomes such as substance abuse, antisocial personality disorder among other issues. In recent years, there has been an increase in research in the molecular and genetic underpinnings of aggressive behavior, and one of the candidate genes codes for the catechol-O-methyltransferase (COMT). COMT is involved in catabolizing catecholamines such as dopamine. These neurotransmitters appear to be involved in regulating mood which can contribute to aggression. The most common gene variant studied in the COMT gene is the Valine (Val) to Methionine (Met) substitution at codon 158. We will be reviewing the current literature on this gene variant in aggressive behavior. PMID:26630958
11C-methionine translocation in barley

International Nuclear Information System (INIS)

Nakanishi, Hiromi; Bughio, Naimatullah; Shigeta Ishioka, Noriko

2000-01-01

11 C-methionine was supplied to barley plants through a single leaf or via the roots and real time 11 C movement was monitored using a PETIS (positron emitting tracer imaging system). In Fe-deficient plants, 11 C-methionine was translocated from the tip of the absorbing leaf to the discrimination center' at the basal part of the shoot and then retranslocated to all the chlorotic leaves, while a negligible amount was retranslocated to the roots. In Fe-sufficient plants, methionine was translocated from the absorbing leaf to the discrimination center and then only to the newest leaf on the main shoot. A negligible amount was also retranslocated to the roots. Although, in Fe-sufficient plants, methionine translocation was observed from absorbing roots to shoots, in Fe-deficient plants, only a little amount was translocated from roots to shoots. In conclusion, methionine from the upper portion of a plant is not used as a precursor of mugineic acid under Fe-deficiency conditions. (author)
Immobilization of an L-aminoacylase-producing strain of Aspergillus oryzae into gelatin pellets and its application in the resolution of D,L-methionine.

Science.gov (United States)

Yuan Yj, Ying-jin; Wang Sh, Shu-hao; Song Zx, Zheng-xiao; Gao Rc, Rui-chang

2002-04-01

The conditions for immobilization of an l-aminoacylase-producing strain of Aspergillus oryzae in gelatin and the enzymic characteristics of the immobilized pellets were studied. The optimal concentrations of gelatin, glutaraldehyde and ethyldiamine and time of immobilization were determined. Scanning electron micrographs reveal the cross-linked structure differences between the native and immobilized pellets. Optimum pH and temperature of the native and immobilized pellets were determined. Effects of ionic strength and substrate concentration on relative activity of the native and immobilized pellets were investigated in detail. The immobilized pellets were more stable over broader temperature and pH ranges. In addition, the immobilized pellets showed stable activity under operational and storage conditions. The immobilized pellets lost about 20% of their initial activity after five cycles of reuse. The results reported in this paper show the potential for using the immobilized A. oryzae pellets to resolve d,l-methionine.
Methionine sulfoxide profiling of milk proteins to assess the influence of lipids on protein oxidation in milk.

Science.gov (United States)

Wüst, Johannes; Pischetsrieder, Monika

2016-06-15

Thermal treatment of milk and milk products leads to protein oxidation, mainly the formation of methionine sulfoxide. Reactive oxygen species, responsible for the oxidation, can be generated by Maillard reaction, autoxidation of sugars, or lipid peroxidation. The present study investigated the influence of milk fat on methionine oxidation in milk. For this purpose, quantitative methionine sulfoxide profiling of all ten methionine residues of β-lactoglobulin, α-lactalbumin, and αs1-casein was carried out by ultrahigh-performance liquid chromatography-electrospray ionization tandem mass spectrometry with scheduled multiple reaction monitoring (UHPLC-ESI-MS/MS-sMRM). Analysis of defatted and regular raw milk samples after heating for up to 8 min at 120 °C and analysis of ultrahigh-temperature milk samples with 0.1%, 1.5%, and 3.5% fat revealed that methionine oxidation of the five residues of the whey proteins and of residues M 123, M 135, and M 196 of αs1-casein was not affected or even suppressed in the presence of milk fat. Only the oxidation of residues M 54 and M 60 of αs1-casein was promoted by lipids. In evaporated milk samples, formation of methionine sulfoxide was hardly influenced by the fat content of the samples. Thus, it can be concluded that lipid oxidation products are not the major cause of methionine oxidation in milk.
Flavivirus methyltransferase as target for virus treatment

Czech Academy of Sciences Publication Activity Database

Krafčíková, Petra; Chalupská, Dominika; Hercík, Kamil; Nencka, Radim; Bouřa, Evžen

2017-01-01

Roč. 284, Suppl 1 (2017), s. 216-217 ISSN 1742-464X. [FEBS Congress /42./ From Molecules to Cells and Back. 10.09.2017-14.09.2017, Jerusalem] Institutional support: RVO:61388963 Keywords : flavivirus methyltransferase * antivirals Subject RIV: CE - Biochemistry
The histone methyltransferase SET8 is required for S-phase progression

DEFF Research Database (Denmark)

Jørgensen, Stine; Elvers, Ingegerd; Trelle, Morten Beck

2008-01-01

Chromatin structure and function is influenced by histone posttranslational modifications. SET8 (also known as PR-Set7 and SETD8) is a histone methyltransferase that monomethylates histonfe H4-K20. However, a function for SET8 in mammalian cell proliferation has not been determined. We show...
Expression of methionine adenosyltransferase 2A in renal cell carcinomas and potential mechanism for kidney carcinogenesis

International Nuclear Information System (INIS)

Wang, Xuliang; Guo, Xiaoqiang; Yu, Wenshui; Li, Cailing; Gui, Yaoting; Cai, Zhiming

2014-01-01

Methionine adenosyltransferase 2A (MAT2A) is an enzyme that catalyzes the formation of S-adenosylmethionine (SAMe) by joining methionine and ATP. SAMe is a methyl donor for transmethylation and has an important role for DNA and/or protein methylation. MAT2A is expressed widely in many tissues especially in kidney. Several studies have demonstrated that there are abnormal expressions of MAT2A in several kinds of cancers such as liver and colon cancers. But the relationship of MAT2A between renal cell carcinomas (RCC) is less understood. The mRNA expression level of the MAT2A gene was determined in 24 RCC patients and 4 RCC cell lines, using real-time quantitative-polymerase chain reaction (RT-PCR). The MAT2A protein content was measured by western blotting and immunohistochemical analysis in 55 RCC patients. The mRNA levels of heme oxygenase-1 (HO-1) and cyclooxygenase-2 (COX-2) were also analysized in patients using RT-PCR. The correlations between the MAT2A and HO-1 as well as COX-2 were analyzed with nonparametric Spearman method. MAT2A transcript was significantly downregulated in cancer tissues compared to normal tissues (P < 0.05). Immunohistochemical analysis and western blotting indicated that level of MAT2A protein was decreased in cancer tissues. The statistical analysis reveals a negative correlation between MAT2A and HO-1 expression in RCC patients and cell lines (P < 0.01). This study demonstrated that MAT2A was lower expression in cancer tissues, suggesting that it may be involved in the development of RCC. MAT2A is a transcriptional corepressor for HO-1 expression by supplying SAM for methyltransferases, which may be one of potential mechanism of MAT2A as tumor suppressor in kidney carcinogenesis
Changes in gene expression following androgen receptor blockade ...

Indian Academy of Sciences (India)

Madhu urs

of gene expression in the ventral prostate, it is not clear whether all the gene expression ... These include clusterin, methionine adenosyl transferase IIα, and prostate-specific ..... MAGEE1 melanoma antigen and no similarity was found with the ...
Methionine sulphoxide reductases revisited: free methionine as a primary target of H2O2 stress in auxotrophic fission yeast

OpenAIRE

García Santamarina, Sarela, 1978-; Boronat i Llop, Susanna, 1965-; Ayté del Olmo, José; Hidalgo Hernando, Elena

2013-01-01

Amino acid methionine can suffer reversible oxidation to sulphoxide and further irreversible over-oxidation to methionine sulphone. As part of the cellular antioxidant scavenging activities are the methionine sulphoxide reductases (Msrs), with a reported role in methionine sulphoxide reduction, both free and in proteins. Three families of Msrs have been described, but the fission yeast genome only includes one representative for two of these families: MsrA/Mxr1 and MsrB/Mxr2. We have investig...
Ribosomal protein methyltransferases in the yeast Saccharomyces cerevisiae: Roles in ribosome biogenesis and translation.

Science.gov (United States)

Al-Hadid, Qais; White, Jonelle; Clarke, Steven

2016-02-12

A significant percentage of the methyltransferasome in Saccharomyces cerevisiae and higher eukaryotes is devoted to methylation of the translational machinery. Methylation of the RNA components of the translational machinery has been studied extensively and is important for structure stability, ribosome biogenesis, and translational fidelity. However, the functional effects of ribosomal protein methylation by their cognate methyltransferases are still largely unknown. Previous work has shown that the ribosomal protein Rpl3 methyltransferase, histidine protein methyltransferase 1 (Hpm1), is important for ribosome biogenesis and translation elongation fidelity. In this study, yeast strains deficient in each of the ten ribosomal protein methyltransferases in S. cerevisiae were examined for potential defects in ribosome biogenesis and translation. Like Hpm1-deficient cells, loss of four of the nine other ribosomal protein methyltransferases resulted in defects in ribosomal subunit synthesis. All of the mutant strains exhibited resistance to the ribosome inhibitors anisomycin and/or cycloheximide in plate assays, but not in liquid culture. Translational fidelity assays measuring stop codon readthrough, amino acid misincorporation, and programmed -1 ribosomal frameshifting, revealed that eight of the ten enzymes are important for translation elongation fidelity and the remaining two are necessary for translation termination efficiency. Altogether, these results demonstrate that ribosomal protein methyltransferases in S. cerevisiae play important roles in ribosome biogenesis and translation. Copyright © 2016 Elsevier Inc. All rights reserved.
Role of Ginkgo Biloba in Hyperhomocysteinemia Induced in Rats By L-Methionine and Gamma Irradiation

International Nuclear Information System (INIS)

Mansour, S.Z.

2011-01-01

The objective of this study is to evaluate the role of Ginkgo biloba in hyperhomocysteinemia and oxidative stress. Methionine was supplied orally to adult male albino rats with a dose of 1.7 g/kg/day during 4 weeks. Irradiation was applied to rats by whole body gamma irradiation with a dose of 2 Gy/week up to a total dose of 8 Gy. Ginkgo biloba (100 mg/kg/day) was supplemented orally to rats, daily, during the period of methionine administration and/or radiation exposure. Biochemical analysis in blood and brain tissues showed that methionine and/or gamma irradiation produced significant increases in homocysteine and acetylcholine esterase levels and significant decrease in nitric oxide (NO). Significant increase in malondialdehyde (MDA) with significant decreases in glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase levels were observed and alteration in plasma lipid profile was also recorded. Ginkgo biloba supplementation has significantly decreased homocysteine and acetylcholine esterase levels and increased NO while was associated with significant improvement of oxidative stress and lipid profile. It could be concluded that the protective effect of Gingko biloba against hyperhomocysteinemia and oxidative stress is attributed to its antioxidant and free radicals scavenging properties.

Determination of thiopurine S-methyltransferase activity by hydrophilic interaction liquid chromatography hyphenated with mass spectrometry.

Science.gov (United States)

Pecher, Daniel; Dokupilová, Svetlana; Zelinková, Zuzana; Peppelenbosch, Maikel; Mikušová, Veronika; Mikuš, Peter

2017-08-05

Thiopurine S-methyltransferase (TPMT) plays an important role in the metabolism of thiopurines used in the therapy of inflammatory bowel diseases (IBD). In this work a new progressive method for the determination of TPMT activity in red blood cells lysates was developed. Analysis was carried out by means of hydrophilic interaction liquid chromatography (HILIC) hyphenated with mass spectrometry (MS). In comparison with reversed-phase high-performance liquid chromatography (RP-HPLC), that has been typically applied in determination of TPMT activity, the HILIC significantly improved the analytical signal provided by MS, shortened analysis time, and improved chromatographic resolution. The HILIC-HPLC-MS method was optimized and validated, providing favorable parameters of detection and quantitation limits (5.5 and 16.5pmol/mL, respectively), linearity (coefficient of determination 0.9999 in the range of 0.01-1.0nmol/mL), recovery and precision (93.25-100.37% with RSD 1.06-1.32% in the whole concentration range of QC samples). Moreover, in contrast to the conventional RP-HPLC-UV approach, the complex phenotype TPMT profiles can be reliably and without interferences monitored using the HILIC-HPLC-MS method. Such advanced monitoring can provide valuable detail information on the thiopurines (e.g. evaluating ratio of methylated and non-methylated 6-mercaptopurine) and, by that, TPMT action in biological systems before and during the therapy of IBD. Copyright © 2017 Elsevier B.V. All rights reserved.
Impaired ovarian functions in arsenic-treated freshwater fish, Colisa fasciatus (bl. and sch. )

Energy Technology Data Exchange (ETDEWEB)

Shukla, J.P.; Pandey, K.

1984-01-01

Arsenic(III) oxide (2.0 mg/l) after 15 and 30 days exposure, and 14.0 mg/l concentration after 15 days exposure, produced no marked histological alteration in the ovary of Colisa fasciatus during its mature phase, whereas 14.0 mg/l arsenic(III) oxide concentration after 30 days exposure decreased the development of oocyte (II and III stage), reduced the number and diameter of nucleoli and increased the number of atretic follicles. The possible mechanism for these alterations is discussed.
Flow-based determination of methionine in pharmaceutical formulations exploiting TGA-capped CdTe quantum dots for enhancing the luminol-KIO{sub 4} chemiluminescence

Energy Technology Data Exchange (ETDEWEB)

Zhou, Min, E-mail: mzhou8367@sina.com [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Wang, Ailian [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Jiuquan Enviromental Protection Bureau, Jiuquan 735000 (China); Li, Cong; Luo, Xiaowei; Ma, Yongjun [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

2017-03-15

A novel flow-injection chemiluminescence method (FI-CL) was established for the determination of methionine in this paper, based on its strong enhancement on CL intensity of the luminol-KIO{sub 4} system catalyzed by thioglycolic acid-capped CdTe quantum dots in alkaline media. Under the optimized conditions, the relative CL intensity was in proportion to methionine concentration in the range from 1.0×10{sup −8} to 1.0×10{sup −5} g mL{sup −1} with a detection limit of 6.6×10{sup −9} g mL{sup −1} (3σ). The relative standard deviation (RSD) of the CL intensity for 1.0×10{sup −6} g mL{sup −1} standard methionine solution was 0.97% (n=11). The proposed method was successfully applied to determine methionine in commercial pharmaceutical formulations with recoveries between 98.0% and 101.9%. The possible CL mechanism was discussed as well. - Graphical abstract: Methionine in commercial pharmaceutical formulations was determined by flow-injection chemiluminescence and the possible chemiluminescence mechanism was discussed as well.
The interplay between protein L-isoaspartyl methyltransferase activity and insulin-like signaling to extend lifespan in Caenorhabditis elegans.

Directory of Open Access Journals (Sweden)

Shilpi Khare

Full Text Available The protein L-isoaspartyl-O-methyltransferase functions to initiate the repair of isomerized aspartyl and asparaginyl residues that spontaneously accumulate with age in a variety of organisms. Caenorhabditis elegans nematodes lacking the pcm-1 gene encoding this enzyme display a normal lifespan and phenotype under standard laboratory growth conditions. However, significant defects in development, egg laying, dauer survival, and autophagy have been observed in pcm-1 mutant nematodes when deprived of food and when exposed to oxidative stress. Interestingly, overexpression of this repair enzyme in both Drosophila and C. elegans extends adult lifespan under thermal stress. In this work, we show the involvement of the insulin/insulin-like growth factor-1 signaling (IIS pathway in PCM-1-dependent lifespan extension in C. elegans. We demonstrate that reducing the levels of the DAF-16 downstream transcriptional effector of the IIS pathway by RNA interference reduces the lifespan extension resulting from PCM-1 overexpression. Using quantitative real-time PCR analysis, we show the up-regulation of DAF-16-dependent stress response genes in the PCM-1 overexpressor animals compared to wild-type and pcm-1 mutant nematodes under mild thermal stress conditions. Additionally, similar to other long-lived C. elegans mutants in the IIS pathway, including daf-2 and age-1 mutants, PCM-1 overexpressor adult animals display increased resistance to severe thermal stress, whereas pcm-1 mutant animals survive less long under these conditions. Although we observe a higher accumulation of damaged proteins in pcm-1 mutant nematodes, the basal level of isoaspartyl residues detected in wild-type animals was not reduced by PCM-1 overexpression. Our results support a signaling role for the protein L-isoaspartyl methyltransferase in lifespan extension that involves the IIS pathway, but that may be independent of its function in overall protein repair.
Functional characterization of a rice de novo DNA methyltransferase, OsDRM2, expressed in Escherichia coli and yeast

Energy Technology Data Exchange (ETDEWEB)

Pang, Jinsong, E-mail: pangjs542@nenu.edu.cn [Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, Jilin 130024 (China); Dong, Mingyue; Li, Ning; Zhao, Yanli [Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, Jilin 130024 (China); Liu, Bao, E-mail: baoliu@nenu.edu.cn [Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, Jilin 130024 (China)

2013-03-01

Highlights: ► A rice de novo DNA methyltransferase OsDRM2 was cloned. ► In vitro methylation activity of OsDRM2 was characterized with Escherichia coli. ► Assays of OsDRM2 in vivo methylation were done with Saccharomyces cerevisiae. ► OsDRM2 methylation activity is not preferential to any type of cytosine context. ► The activity of OsDRM2 is independent of RdDM pathway. - Abstract: DNA methylation of cytosine nucleotides is an important epigenetic modification that occurs in most eukaryotic organisms and is established and maintained by various DNA methyltransferases together with their co-factors. There are two major categories of DNA methyltransferases: de novo and maintenance. Here, we report the isolation and functional characterization of a de novo methyltransferase, named OsDRM2, from rice (Oryza sativa L.). The full-length coding region of OsDRM2 was cloned and transformed into Escherichia coli and Saccharomyces cerevisiae. Both of these organisms expressed the OsDRM2 protein, which exhibited stochastic de novo methylation activity in vitro at CG, CHG, and CHH di- and tri-nucleotide patterns. Two lines of evidence demonstrated the de novo activity of OsDRM2: (1) a 5′-CCGG-3′ containing DNA fragment that had been pre-treated with OsDRM2 protein expressed in E. coli was protected from digestion by the CG-methylation-sensitive isoschizomer HpaII; (2) methylation-sensitive amplified polymorphism (MSAP) analysis of S. cerevisiae genomic DNA from transformants that had been introduced with OsDRM2 revealed CG and CHG methylation levels of 3.92–9.12%, and 2.88–6.93%, respectively, whereas the mock control S. cerevisiae DNA did not exhibit cytosine methylation. These results were further supported by bisulfite sequencing of the 18S rRNA and EAF5 genes of the transformed S. cerevisiae, which exhibited different DNA methylation patterns, which were observed in the genomic DNA. Our findings establish that OsDRM2 is an active de novo DNA
Functional characterization of a rice de novo DNA methyltransferase, OsDRM2, expressed in Escherichia coli and yeast

International Nuclear Information System (INIS)

Pang, Jinsong; Dong, Mingyue; Li, Ning; Zhao, Yanli; Liu, Bao

2013-01-01

Highlights: ► A rice de novo DNA methyltransferase OsDRM2 was cloned. ► In vitro methylation activity of OsDRM2 was characterized with Escherichia coli. ► Assays of OsDRM2 in vivo methylation were done with Saccharomyces cerevisiae. ► OsDRM2 methylation activity is not preferential to any type of cytosine context. ► The activity of OsDRM2 is independent of RdDM pathway. - Abstract: DNA methylation of cytosine nucleotides is an important epigenetic modification that occurs in most eukaryotic organisms and is established and maintained by various DNA methyltransferases together with their co-factors. There are two major categories of DNA methyltransferases: de novo and maintenance. Here, we report the isolation and functional characterization of a de novo methyltransferase, named OsDRM2, from rice (Oryza sativa L.). The full-length coding region of OsDRM2 was cloned and transformed into Escherichia coli and Saccharomyces cerevisiae. Both of these organisms expressed the OsDRM2 protein, which exhibited stochastic de novo methylation activity in vitro at CG, CHG, and CHH di- and tri-nucleotide patterns. Two lines of evidence demonstrated the de novo activity of OsDRM2: (1) a 5′-CCGG-3′ containing DNA fragment that had been pre-treated with OsDRM2 protein expressed in E. coli was protected from digestion by the CG-methylation-sensitive isoschizomer HpaII; (2) methylation-sensitive amplified polymorphism (MSAP) analysis of S. cerevisiae genomic DNA from transformants that had been introduced with OsDRM2 revealed CG and CHG methylation levels of 3.92–9.12%, and 2.88–6.93%, respectively, whereas the mock control S. cerevisiae DNA did not exhibit cytosine methylation. These results were further supported by bisulfite sequencing of the 18S rRNA and EAF5 genes of the transformed S. cerevisiae, which exhibited different DNA methylation patterns, which were observed in the genomic DNA. Our findings establish that OsDRM2 is an active de novo DNA
LuxS impacts on LytA-dependent autolysis and on competence in Streptococcus pneumoniae.

Science.gov (United States)

Romao, Susana; Memmi, Guido; Oggioni, Marco R; Trombe, Marie-Claude

2006-02-01

The ubiquitous protein LuxS with S-ribosylhomocysteinase activity is involved in S-adenosyl methionine detoxification, C-1 unit recycling and the production of autoinducers that allow the cell to sense and respond to cell density. Independent reports describe the impact of LuxS deficiency on Streptococcus pneumoniae virulence in the mouse. In vitro, LuxS deficiency confers discrete phenotypes. A combined approach using genetic dissection and mixed-culture experiments allowed the involvement of LuxS in the developmental physiology of S. pneumoniae to be investigated. Functional LuxS was found to be related on the one hand to down-regulation of competence, and on the other hand to attenuation of autolysis in cultures entering stationary phase. The competence phenotype of luxS mutant bacteria was complemented by media conditioned by competence-defective ComAB0 bacteria, but not by BSA. The autolytic phenotype was complemented by BSA, but not by conditioned supernatants. It is suggested that the impact of LuxS on competence, but not on autolysis, involves cell-cell communication. The phenotype of luxS mutant strains reveals a hierarchy in the competence regulatory networks of S. pneumoniae.
Betaine is as effective as folate at re-synthesizing methionine for protein synthesis during moderate methionine deficiency in piglets.

Science.gov (United States)

McBreairty, Laura E; Robinson, Jason L; Harding, Scott V; Randell, Edward W; Brunton, Janet A; Bertolo, Robert F

2016-12-01

Both folate and betaine (synthesized from choline) are nutrients used to methylate homocysteine to reform the amino acid methionine following donation of its methyl group; however, it is unclear whether both remethylation pathways are of equal importance during the neonatal period when remethylation rates are high. Methionine is an indispensable amino acid that is in high demand in neonates not only for protein synthesis, but is also particularly important for transmethylation reactions, such as creatine and phosphatidylcholine synthesis. The objective of this study was to determine whether supplementation with folate, betaine, or a combination of both can equally re-synthesize methionine for protein synthesis when dietary methionine is limiting. Piglets were fed a low methionine diet devoid of folate, choline, and betaine, and on day 6, piglets were supplemented with either folate, betaine, or folate + betaine (n = 6 per treatment) until day 10. [1- 13 C]-phenylalanine oxidation was measured as an indicator of methionine availability for protein synthesis both before and after 2 days of supplementation. Prior to supplementation, piglets had lower concentrations of plasma folate, betaine, and choline compared to baseline with no change in homocysteine. Post-supplementation, phenylalanine oxidation levels were 20-46 % lower with any methyl donor supplementation (P = 0.006) with no difference among different supplementation groups. Furthermore, both methyl donors led to similarly lower concentrations of homocysteine following supplementation (P folate to remethylate methionine for protein synthesis, as indicated by lower phenylalanine oxidation.
Metabolic Regulation of Methionine Restriction in Diabetes.

Science.gov (United States)

Yin, Jie; Ren, Wenkai; Chen, Shuai; Li, Yuying; Han, Hui; Gao, Jing; Liu, Gang; Wu, Xin; Li, Tiejun; Kim, Sung Woo; Yin, Yulong

2018-03-30

Although the effects of dietary methionine restriction have been investigated in the physiology of aging and diseases related to oxidative stress, the relationship between methionine restriction and the development of metabolic disorders has not been explored extensively. This review summarizes studies of the possible involvement of dietary methionine restriction in improving insulin resistance, glucose homeostasis, oxidative stress, lipid metabolism, the pentose phosphate pathway, and inflammation, with an emphasis on the fibroblast growth factor 21 and protein phosphatase 2A signals and autophagy in diabetes. Diets deficient in methionine may be a useful nutritional strategy in patients with diabetes. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Constitutive expression of feedback-insensitive cystathionine γ-synthase increases methionine levels in soybean leaves and seeds

Institute of Scientific and Technical Information of China (English)

YU Yang; HOU Wen-sheng; YaeI Hacham; SUN Shi; WU Cun-xiang; Ifat Matityahu; SONG Shikui; RacheI Amir; HAN Tian-fu

2018-01-01

Soybean (Glycine max (L.) Merr.) is a major crop that provides plant-origin protein and oil for humans and livestock. Although the soybean vegetative tissues and seeds provide a major source of high-quality protein, they suffer from low concentration of an essential sulfur-containing amino acid, methionine, which significantly limits their nutritional quality. The level of methionine is mainly controlled by the first unique enzyme of methionine synthesis, cystathione γ-synthase (CGS). Aiming to elevate methionine level in vegetative tissues and seeds, we constitutively over-expressed a feedback-insensitive Arabidopsis CGS (AtD-CGS) in soybean cultivars, Zigongdongdou (ZD) and Jilinxiaoli 1 (JX). The levels of soluble methionine increased remarkably in leaves of transgenic soybeans compared to wild-type plants (6.6- and 7.3-fold in two transgenic ZD lines, and 3.7-fold in one transgenic JX line). Furthermore, the total methionine contents were significantly increased in seeds of the transgenic ZD lines (1.5- to 4.8-fold increase) and the transgenic JX lines (1.3- to 2.3-fold increase) than in the wild type. The protein contents of the transgenic soybean seeds were significantly elevated compared to the wild type, suggesting that the scarcity of methionine in soybeans may limit protein accumulation in soybean seeds. The increased protein content did not alter the profile of major storage proteins in the seeds. Generally, this study provides a promising strategy to increase the levels of methionine and protein in soybean through the breeding programs.
New metabolic labelling medium for Trichomonas vaginalis and Tritrichomonas foetus using 35S methionine

Energy Technology Data Exchange (ETDEWEB)

Torian, B.E.; Kenny, G.E.

1986-04-01

A metabolic labelling medium was devised for Trichomonas vaginalis and Tritrichomonas foetus utilizing 35S methionine. T. vaginalis cultured for 24h in the medium took up approximately 27% of the available label and increased greater than two fold in number. Counts per microgram of protein were 32,555 +/- 10% between different strains or identical strains in different labelling runs. T. foetus took up approximately 5% of the available label and increased greater than two fold in 24h. This resulted in specific labelling of 12,704 cpm/ug protein +/- 10% between different runs with the same strain.
New metabolic labelling medium for Trichomonas vaginalis and Tritrichomonas foetus using 35S methionine

International Nuclear Information System (INIS)

Torian, B.E.; Kenny, G.E.

1986-01-01

A metabolic labelling medium was devised for Trichomonas vaginalis and Tritrichomonas foetus utilizing 35S methionine. T. vaginalis cultured for 24h in the medium took up approximately 27% of the available label and increased greater than two fold in number. Counts per microgram of protein were 32,555 +/- 10% between different strains or identical strains in different labelling runs. T. foetus took up approximately 5% of the available label and increased greater than two fold in 24h. This resulted in specific labelling of 12,704 cpm/ug protein +/- 10% between different runs with the same strain
The First International Mini-Symposium on Methionine Restriction and Lifespan

Directory of Open Access Journals (Sweden)

Gene eAbles

2014-05-01

Full Text Available It has been 20 years since the Orentreich Foundation for the Advancement of Science, under the leadership Dr. Norman Orentreich, first reported that low methionine (Met ingestion by rats extends lifespan [1]. Since then, several studies have replicated the effects of dietary methionine restriction (MR in delaying age-related diseases [2–5]. We report the abstracts from the First International Mini-Symposium on Methionine Restriction and Lifespan held in Tarrytown, NY last September 2013. The goals were 1 to gather researchers with an interest in methionine restriction and lifespan, 2 to exchange knowledge, 3 to generate ideas for future investigations, and 4 to strengthen relationships within this community. The presentations highlighted the importance of research on cysteine, growth hormone (GH, and ATF4 in the paradigm of aging. In addition, the effects of dietary restriction or MR in the kidneys, liver, bones and the adipose tissue were discussed. The symposium also emphasized the value of other species, e.g. the naked mole rat, Brandt’s bat and drosophila in aging research. Overall, the symposium consolidated scientists with similar research interests and provided opportunities to conduct future collaborative studies.
Role of methionine on epigenetic modification of DNA methylation and gene expression in animals

Directory of Open Access Journals (Sweden)

Naifeng Zhang

2018-03-01

Full Text Available DNA methylation is one of the main epigenetic phenomena affecting gene expression. It is an important mechanism for the development of embryo, growth and health of animals. As a key nutritional factor limiting the synthesis of protein, methionine serves as the precursor of S-adenosylmethionine (SAM in the hepatic one-carbon metabolism. The dietary fluctuation of methionine content can alter the levels of metabolic substrates in one-carbon metabolism, e.g., the SAM, S-adenosylhomocysteine (SAH, and change the expression of genes related to the growth and health of animals by DNA methylation reactions. The ratio of SAM to SAH is called ‘methylation index’ but it should be carefully explained because the complexity of methylation reaction. Alterations of methylation in a specific cytosine-guanine (CpG site, rather than the whole promoter region, might be enough to change gene expression. Aberrant methionine cycle may provoke molecular changes of one-carbon metabolism that results in deregulation of cellular hemostasis and health problems. The importance of DNA methylation has been underscored but the mechanisms of methionine affecting DNA methylation are poorly understood. Nutritional epigenomics provides a promising insight into the targeting epigenetic changes in animals from a nutritional standpoint, which will deepen and expand our understanding of genes, molecules, tissues, and animals in which methionine alteration influences DNA methylation and gene expression. Keywords: Epigenetics, Methionine, DNA methylation, Gene expression, Epigenetic modification
In situ localization of phenylpropanoid biosynthetic mRNAs and proteins in Parsley (Petroselinum crispum)

International Nuclear Information System (INIS)

Reinold, S.; Hahlbrock, K.

1997-01-01

Using in situ RNA/RNA hybridization, enzyme immunolocalization, and histochemical techniques, several phenylpropanoid biosynthetic activities and products were localized in tissue sections from various aerial parts of parsley (Petroselinum crispum) plants at different developmental stages. The enzymes and corresponding mRNAs analyzed included two representatives of general phenylpropanoid metabolism: phenylalanine ammonia-lyase (PAL) and 4-coumarate: CoA ligase (4CL), and one representative each from two distinct branch pathways: chalcone synthase (CHS; flavonoids) and S-adenosyl-L-methionine: bergaptol O-methyltransferase (BMT; furanocoumarins). In almost all cases, the relative timing of accumulation differed greatly for mRNA and protein and indicated short expression periods and short half-lives for all mRNAs as compared to the proteins. PAL and 4CL occurred almost ubiquitously in cell type-specific patterns, and their mRNAs and proteins were always coordinately expressed, whereas the cell type-specific localization of flavonoid and furanocoumarin biosynthetic activities was to a large extent mutually exclusive. However, the distribution patterns of CHS and BMT, when superimposed, closely matched those of PAL and 4CL in nearly all tissues analysed, suggesting that the flavonoid and furanocoumarin pathways together constituted a large majority of the total phenylpropanoid biosynthetic activity. Differential sites of synthesis and accumulation indicating intercellular translocation were observed both for flavonoids and for furanocoumarins in oil ducts and the surrounding tissue. The widespread occurrence of both classes of compounds, as well as selected, pathway-specific mRNAs and enzymes, in many cell types of all parsley organs including various flower parts suggests additional functions beyond the previously established roles of flavonoids in UV protection and furanocoumarins in pathogen defence. (author)
Human C6orf211 Encodes Armt1, a Protein Carboxyl Methyltransferase that Targets PCNA and Is Linked to the DNA Damage Response

Directory of Open Access Journals (Sweden)

J. Jefferson P. Perry

2015-03-01

Full Text Available Recent evidence supports the presence of an L-glutamyl methyltransferase(s in eukaryotic cells, but this enzyme class has been defined only in certain prokaryotic species. Here, we characterize the human C6orf211 gene product as “acidic residue methyltransferase-1” (Armt1, an enzyme that specifically targets proliferating cell nuclear antigen (PCNA in breast cancer cells, predominately methylating glutamate side chains. Armt1 homologs share structural similarities with the SAM-dependent methyltransferases, and negative regulation of activity by automethylation indicates a means for cellular control. Notably, shRNA-based knockdown of Armt1 expression in two breast cancer cell lines altered survival in response to genotoxic stress. Increased sensitivity to UV, adriamycin, and MMS was observed in SK-Br-3 cells, while in contrast, increased resistance to these agents was observed in MCF7 cells. Together, these results lay the foundation for defining the mechanism by which this post-translational modification operates in the DNA damage response (DDR.
Pichia pastoris Mut(S) strains are prone to misincorporation of O-methyl-L-homoserine at methionine residues when methanol is used as the sole carbon source.

Science.gov (United States)

Schotte, Peter; Dewerte, Isabelle; De Groeve, Manu; De Keyser, Saskia; De Brabandere, Veronique; Stanssens, Patrick

2016-06-07

Over the last few decades the methylotrophic yeast Pichia pastoris has become a popular host for a wide range of products such as vaccines and therapeutic proteins. Several P. pastoris engineered strains and mutants have been developed to improve the performance of the expression system. Yield and quality of a recombinant product are important parameters to monitor during the host selection and development process but little information is published regarding quality differences of a product produced by different P. pastoris strains. We compared titer and quality of several Nanobodies(®) produced in wild type and Mut(S) strains. Titer in fed-batch fermentation was comparable between all strains for each Nanobody but a significant difference in quality was observed. Nanobodies expressed in Mut(S) strains contained a product variant with a Δ-16 Da mass difference that was not observed in wild type strains. This variant showed substitution of methionine residues due to misincorporation of O-methyl-L-homoserine, also called methoxine. Methoxine is likely synthesized by the enzymatic action of O-acetyl homoserine sulfhydrylase and we confirmed that Nanobodies produced in the corresponding knock-out strain contained no methoxine variants. We could show the incorporation of methoxine during biosynthesis by its addition to the culture medium. We showed that misincorporation of methoxine occurs particularly in P. pastoris Mut(S) strains. This reduction in product quality could outweigh the advantages of using Mut strains, such as lower oxygen and methanol demand, heat formation and in some cases improved expression. Methoxine incorporation in recombinant proteins is likely to occur when an excess of methanol is present during fermentation but can be avoided when the methanol feed rate protocol is carefully designed.
N-methylation of the heterogeneous nuclear ribonucleoproteins in HeLa cells

International Nuclear Information System (INIS)

Rieker, J.P.

1984-01-01

Several of the core proteins on the 40S heterogeneous nuclear ribonucleoprotein particles (hnRNP) from HeLa cells contain N/sup G/,N/sup G/-dimethyl-L-arginine (uDMA). 3-deazaadenosine (c 3 Ado), an inhibitor of and substrate for s-adenosyl-L-homocysteine hydrolase, has been used to study the methylation patterns of the individual polypeptides. Trimethyllysine and uDMA formation in total cellular protein were inhibited in the presence of the drug while other methylated basic amino acids were unaffected. This inhibition was reversed within 60 min after removal of the drug from the medium. Monolayer HeLa cultures were incubated with [methyl- 3 H]-L-methoinine for 12 hours in the presence of 50 uM c 3 Ado. Purified particles were obtained by centrifugation of nuclear extracts on sucrose density gradients. The core proteins were isolated by two-dimensional gel electrophoresis, acid hydrolyzed and analyzed for radioactivity incorporated into methionine and methylated basic amino acids. The ratio of radioactivity incorporated into uDMA relative to that into methionine for the two major particle proteins with molecular weights of 31,000 (A 1 ) and 43,000 (A 2 ) was about 2.0 and 0.2 in control cultures. In the presence of c 3 Ado, these ratios were depressed 60 to 80%. Results of pulse-chase experiments suggested that A 1 and A 2 are metabolically stable proteins (t/sub 0.5/ > 75 hr), whether or not the proteins were undermethylated. Monomethyl-L-arginine may be a precursor in the formation of u-DMA
S1 pocket fingerprints of human and bacterial methionine aminopeptidases determined using fluorogenic libraries of substrates and phosphorus based inhibitors

Czech Academy of Sciences Publication Activity Database

Poreba, M.; Gajda, A.; Pícha, Jan; Jiráček, Jiří; Marschner, A.; Klein, Ch. D.; Salvesen, G. S.; Drag, M.

2012-01-01

Roč. 94, č. 3 (2012), s. 704-710 ISSN 0300-9084 R&D Projects: GA MŠk(CZ) LC06077 Institutional research plan: CEZ:AV0Z40550506 Keywords : methionine aminopeptidase * substrate library * protease * enzyme * inhibitor * substrate specificity Subject RIV: CC - Organic Chemistry Impact factor: 3.142, year: 2012
Association of codon 108/158 catechol-O-methyltransferase gene polymorphism with the psychiatric manifestations of velo-cardio-facial syndrome

Energy Technology Data Exchange (ETDEWEB)

Lachman, H.M.; Papolos, D.F.; Veit, S. [Albert Einstein College of Medicine, Bronx, NY (United States)] [and others

1996-09-20

Velo-cardio-facial-syndrome (VCFS) is a common congenital disorder associated with typical facial appearance, cleft palate, cardiac defects, and learning disabilities. The majority of patients have an interstitial deletion on chromosome 22q11. In addition to physical abnormalities, a variety of psychiatric illnesses have been reported in patients with VCFS, including schizophrenia, bipolar disorder, and attention deficit hyperactivity disorder. The psychiatric manifestations of VCFS could be due to haploinsufficiency of a gene(s) within 22q11. One candidate that has been mapped to this region is catechol-O-methyltransferase (COMT). We recently identified a polymorphism in the COMT gene that leads to a valine{r_arrow}methionine substitution at amino acid 158 of the membrane-bound form of the enzyme. Homozygosity for COMT158{sup met} leads to a 3- to 4-fold reduction in enzymatic activity, compared with homozygotes for COMT158{sup met}. We now report that in a population of patients with VCFS, there is an apparent association between the low-activity allele, COMT158{sup met}, and the development of bipolar spectrum disorder, and in particular, a rapid-cycling form. 33 refs., 3 tabs.

Methionine Metabolites in Patients With Sepsis.

Science.gov (United States)

Wexler, Orren; Gough, Michael S; Morgan, Mary Anne M; Mack, Cynthia M; Apostolakos, Michael J; Doolin, Kathleen P; Mooney, Robert A; Arning, Erland; Bottiglieri, Teodoro; Pietropaoli, Anthony P

2018-01-01

Sepsis is characterized by microvascular dysfunction and thrombophilia. Several methionine metabolites may be relevant to this sepsis pathophysiology. S-adenosylmethionine (SAM) serves as the methyl donor for trans-methylation reactions. S-adenosylhomocysteine (SAH) is the by-product of these reactions and serves as the precursor to homocysteine. Relationships between plasma total homocysteine concentrations (tHcy) and vascular disease and thrombosis are firmly established. We hypothesized that SAM, SAH, and tHcy levels are elevated in patients with sepsis and associated with mortality. This was a combined case-control and prospective cohort study consisting of 109 patients with sepsis and 50 control participants without acute illness. The study was conducted in the medical and surgical intensive care units of the University of Rochester Medical Center. Methionine, SAM, SAH, and tHcy concentrations were compared in patients with sepsis versus control participants and in sepsis survivors versus nonsurvivors. Patients with sepsis had significantly higher plasma SAM and SAH concentrations than control participants (SAM: 164 [107-227] vs73 [59-87 nM], P sepsis patients compared to healthy control participants (4 [2-6]) vs 7 [5-9] μM; P = .04). In multivariable analysis, quartiles of SAM, SAH, and tHcy were independently associated with sepsis ( P = .006, P = .05, and P Sepsis nonsurvivors had significantly higher plasma SAM and SAH concentrations than survivors (SAM: 223 [125-260] vs 136 [96-187] nM; P = .01; SAH: 139 [81-197] vs 86 [55-130] nM, P = .006). Plasma tHcy levels were similar in survivors vs nonsurvivors. The associations between SAM or SAH and hospital mortality were no longer significant after adjusting for renal dysfunction. Methionine metabolite concentrations are abnormal in sepsis and linked with clinical outcomes. Further study is required to determine whether these abnormalities have pathophysiologic significance.
Roles of DNA methyltransferases in Arabidopsis development ...

African Journals Online (AJOL)

Mutations that cause severe loss of DNA methylation often leads to abnormal development. In the present review, we summarized recent findings of the three major DNA methyltransferases mutants playing vital role in development of Arabidopsis thaliana. Keywords: DNA methylation, epigenetics, methyltransferase, mutant ...
Prebiotic Synthesis of Methionine and Other Sulfur-Containing Organic Compounds on the Primitive Earth: A Contemporary Reassessment Based on an Unpublished 1958 Stanley Miller Experiment

Science.gov (United States)

Parker, Eric T.; Cleaves, H. James; Callahan, Michael P.; Dworkin, Jason P.; Glavin, Daniel P.; Lazcano, Antonio

2010-01-01

Original extracts from an unpublished 1958 experiment conducted by the late Stanley L. Miller were recently found and analyzed using modern state-of-the-art analytical methods. The extracts were produced by the action of an electric discharge on a mixture of methane (CH4), hydrogen sulfide (H2S), ammonia (NH3), and carbon dioxide (CO2). Racemic methionine was farmed in significant yields, together with other sulfur-bearing organic compounds. The formation of methionine and other compounds from a model prebiotic atmosphere that contained H2S suggests that this type of synthesis is robust under reducing conditions, which may have existed either in the global primitive atmosphere or in localized volcanic environments on the early Earth. The presence of a wide array of sulfur-containing organic compounds produced by the decomposition of methionine and cysteine indicates that in addition to abiotic synthetic processes, degradation of organic compounds on the primordial Earth could have been important in diversifying the inventory of molecules of biochemical significance not readily formed from other abiotic reactions, or derived from extraterrestrial delivery.
Independent Evolution of Six Families of Halogenating Enzymes.

Science.gov (United States)

Xu, Gangming; Wang, Bin-Gui

2016-01-01

Halogenated natural products are widespread in the environment, and the halogen atoms are typically vital to their bioactivities. Thus far, six families of halogenating enzymes have been identified: cofactor-free haloperoxidases (HPO), vanadium-dependent haloperoxidases (V-HPO), heme iron-dependent haloperoxidases (HI-HPO), non-heme iron-dependent halogenases (NI-HG), flavin-dependent halogenases (F-HG), and S-adenosyl-L-methionine (SAM)-dependent halogenases (S-HG). However, these halogenating enzymes with similar biological functions but distinct structures might have evolved independently. Phylogenetic and structural analyses suggest that the HPO, V-HPO, HI-HPO, NI-HG, F-HG, and S-HG enzyme families may have evolutionary relationships to the α/β hydrolases, acid phosphatases, peroxidases, chemotaxis phosphatases, oxidoreductases, and SAM hydroxide adenosyltransferases, respectively. These halogenating enzymes have established sequence homology, structural conservation, and mechanistic features within each family. Understanding the distinct evolutionary history of these halogenating enzymes will provide further insights into the study of their catalytic mechanisms and halogenation specificity.
Bacterial variations on the methionine salvage pathway

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Haas Dieter

2004-03-01

Full Text Available Abstract Background The thiomethyl group of S-adenosylmethionine is often recycled as methionine from methylthioadenosine. The corresponding pathway has been unravelled in Bacillus subtilis. However methylthioadenosine is subjected to alternative degradative pathways depending on the organism. Results This work uses genome in silico analysis to propose methionine salvage pathways for Klebsiella pneumoniae, Leptospira interrogans, Thermoanaerobacter tengcongensis and Xylella fastidiosa. Experiments performed with mutants of B. subtilis and Pseudomonas aeruginosa substantiate the hypotheses proposed. The enzymes that catalyze the reactions are recruited from a variety of origins. The first, ubiquitous, enzyme of the pathway, MtnA (methylthioribose-1-phosphate isomerase, belongs to a family of proteins related to eukaryotic intiation factor 2B alpha. mtnB codes for a methylthioribulose-1-phosphate dehydratase. Two reactions follow, that of an enolase and that of a phosphatase. While in B. subtilis this is performed by two distinct polypeptides, in the other organisms analyzed here an enolase-phosphatase yields 1,2-dihydroxy-3-keto-5-methylthiopentene. In the presence of dioxygen an aci-reductone dioxygenase yields the immediate precursor of methionine, ketomethylthiobutyrate. Under some conditions this enzyme produces carbon monoxide in B. subtilis, suggesting a route for a new gaseous mediator in bacteria. Ketomethylthiobutyrate is finally transaminated by an aminotransferase that exists usually as a broad specificity enzyme (often able to transaminate aromatic aminoacid keto-acid precursors or histidinol-phosphate. Conclusion A functional methionine salvage pathway was experimentally demonstrated, for the first time, in P. aeruginosa. Apparently, methionine salvage pathways are frequent in Bacteria (and in Eukarya, with recruitment of different polypeptides to perform the needed reactions (an ancestor of a translation initiation factor and Ru
21 CFR 172.399 - Zinc methionine sulfate.

Science.gov (United States)

2010-04-01

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.399 Zinc methionine sulfate. Zinc methionine...
Interactions within the mammalian DNA methyltransferase family

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Ehrenhofer-Murray Ann E

2003-05-01

Full Text Available Abstract Background In mammals, epigenetic information is established and maintained via the postreplicative methylation of cytosine residues by the DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b. Dnmt1 is required for maintenance methylation whereas Dnmt3a and Dnmt3b are responsible for de novo methylation. Contrary to Dnmt3a or Dnmt3b, the isolated C-terminal region of Dnmt1 is catalytically inactive, despite the presence of the sequence motifs typical of active DNA methyltransferases. Deletion analysis has revealed that a large part of the N-terminal domain is required for enzymatic activity. Results The role played by the N-terminal domain in this regulation has been investigated using the yeast two-hybrid system. We show here the presence of an intra-molecular interaction in Dnmt1 but not in Dnmt3a or Dnmt3b. This interaction was confirmed by immunoprecipitation and was localized by deletion mapping. Furthermore, a systematic analysis of interactions among the Dnmt family members has revealed that DNMT3L interacts with the C-terminal domain of Dnmt3a and Dnmt3b. Conclusions The lack of methylating ability of the isolated C-terminal domain of Dnmt1 could be explained in part by a physical interaction between N- and C-terminal domains that apparently is required for activation of the catalytic domain. Our deletion analysis suggests that the tertiary structure of Dnmt1 is important in this process rather than a particular sequence motif. Furthermore, the interaction between DNMT3L and the C-terminal domains of Dnmt3a and Dnmt3b suggests a mechanism whereby the enzymatically inactive DNMT3L brings about the methylation of its substrate by recruiting an active methylase.
Interactions within the mammalian DNA methyltransferase family

Science.gov (United States)

Margot, Jean B; Ehrenhofer-Murray, Ann E; Leonhardt, Heinrich

2003-01-01

Background In mammals, epigenetic information is established and maintained via the postreplicative methylation of cytosine residues by the DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b. Dnmt1 is required for maintenance methylation whereas Dnmt3a and Dnmt3b are responsible for de novo methylation. Contrary to Dnmt3a or Dnmt3b, the isolated C-terminal region of Dnmt1 is catalytically inactive, despite the presence of the sequence motifs typical of active DNA methyltransferases. Deletion analysis has revealed that a large part of the N-terminal domain is required for enzymatic activity. Results The role played by the N-terminal domain in this regulation has been investigated using the yeast two-hybrid system. We show here the presence of an intra-molecular interaction in Dnmt1 but not in Dnmt3a or Dnmt3b. This interaction was confirmed by immunoprecipitation and was localized by deletion mapping. Furthermore, a systematic analysis of interactions among the Dnmt family members has revealed that DNMT3L interacts with the C-terminal domain of Dnmt3a and Dnmt3b. Conclusions The lack of methylating ability of the isolated C-terminal domain of Dnmt1 could be explained in part by a physical interaction between N- and C-terminal domains that apparently is required for activation of the catalytic domain. Our deletion analysis suggests that the tertiary structure of Dnmt1 is important in this process rather than a particular sequence motif. Furthermore, the interaction between DNMT3L and the C-terminal domains of Dnmt3a and Dnmt3b suggests a mechanism whereby the enzymatically inactive DNMT3L brings about the methylation of its substrate by recruiting an active methylase. PMID:12777184
Combining combinatorial chemistry and affinity chromatography protocols for systematically probing protein-ligand interactions: application to the development of highly selective phosphinic inhibitors of human bataine: homocysteine S-methyltransferase

Czech Academy of Sciences Publication Activity Database

Collinsová, Michaela; Garrow, T. A.; Castro, C.; Dive, V.; Yiotakis, A.; Jiráček, Jiří

2002-01-01

Roč. 8, - (2002), s. S221 ISSN 1075-2617. [European Peptide Symposium /27./. 31.08.2002-06.09.2002, Sorrento] Institutional research plan: CEZ:AV0Z4055905 Keywords : homocysteine S-methyltransferase Subject RIV: CE - Biochemistry
Effects of supplementary folic acid and vitamin B(12) on hepatic metabolism of dairy cows according to methionine supply.

Science.gov (United States)

Preynat, A; Lapierre, H; Thivierge, M C; Palin, M F; Cardinault, N; Matte, J J; Desrochers, A; Girard, C L

2010-05-01

The present experiment was undertaken to study the interactions between dietary supplements of rumen-protected methionine (RPM) and intramuscular injections of folic acid and vitamin B(12), given from 3 wk before calving to 16 wk of lactation, on hepatic metabolism of lactating dairy cows. Sixty multiparous Holstein cows were assigned to 10 blocks of 6 cows each according to their previous milk production. Within each block, 3 cows were fed a diet calculated to supply Met as 1.83% of metabolizable protein, whereas the 3 other cows were fed the same diet supplemented with 18g of RPM calculated to provide Met as 2.23% of metabolizable protein. Within each level of Met, the cows received no vitamin supplement or weekly intramuscular injections of 160mg of folic acid alone or combined with 10mg of vitamin B(12). Liver biopsies were taken at 2, 4, 8, and 16 wk of lactation. Liver concentrations of folates and vitamin B(12) were increased by their respective supplements but this response to vitamin supplements was altered by methionine supply. Concentrations of total lipids and triglycerides increased in livers of cows fed RPM, whereas concentrations of cholesterol ester, cholesterol, diglycerides, phosphatidylethanolamine, and phosphatidylcholine were not affected. Folic acid, alone or combined with vitamin B(12), tended to increase the ratio of phosphatidylcholine to phosphatidylethanolamine. Gene expression of 5,10-methylene-tetrahydrofolate reductase, microsomal transfer protein, and phosphatidylethanolamine methyltransferase were higher in liver of cows fed RPM supplements. The relative mRNA abundance of 5,10-methylene-tetrahydrofolate reductase and methylmalonyl-CoA mutase were increased by the combined injections of folic acid and vitamin B(12), whereas those of methionine synthase and methionine synthase reductase were not affected by treatments. These results suggest that increasing supply of methyl groups, as preformed labile methyl groups or through
Methionine as a Precursor of Ethylene—Commentary

Science.gov (United States)

Lieberman et al. showed in a 1966 publication of Plant Physiology that methionine is a precursor of ethylene. It was the first paper that showed ethylene carbons are derived from carbons 3 and 4 of methionine. This paper catalyzed remarkable interest among plant biologists to elucidate the biosynth...
Effects of Methionine Containing Paracetamol Formulation on ...

African Journals Online (AJOL)

Effects of Methionine Containing Paracetamol Formulation on Serum Vitamins and Trace Elements in Male Rats. AA Iyanda, JI Anetor, DP Oparinde, FAA Adeniyi. Abstract. Methionine is an effective antidote in the treatment of paracetamol-induced toxicity but at large doses it has been reported to induce or aggravate a ...
Method for the typing of Clostridium difficile based on polyacrylamide gel electrophoresis of [35S]methionine-labeled proteins

International Nuclear Information System (INIS)

Tabaqchali, S.; O'Farrell, S.; Holland, D.; Silman, R.

1986-01-01

A typing method for Clostridium difficile based on the incorporation of [ 35 S]methionine into cellular proteins, their separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their visualization by autoradiography is described. On analysis of the radiolabeled-protein profiles, nine distinct groups were observed (A to E and W to Z). The method, which is simple, reproducible, and readily expandable, has been applied in epidemiological studies to demonstrate cross-infection and hospital acquisition of C. difficile
Reactions of cisplatin with cysteine and methionine at constant pH; a computational study.

Science.gov (United States)

Zimmermann, Tomás; Burda, Jaroslav V

2010-02-07

Interactions of hydrated cisplatin complexes cis-[Pt(NH(3))(2)Cl(H(2)O)](+) and cis-[Pt(NH(3))(2)(OH)(H(2)O)](+) with cysteine and methionine in an aqueous solution at constant pH were explored using computational methods. Thermodynamic parameters of considered reactions were studied in a broad pH range, taking up to 4 protonation states of each molecule into account. Reaction free energies at constant pH were obtained from standard Gibbs free energies using the Legendre transformation. Solvation free energies and pK(a) values were calculated using the PCM model with UAHF cavities, recently adapted by us for transition metal complexes. The root mean square error of pK(a) values on a set of model platinum complexes and amino acids was equal to 0.74. At pH 7, the transformed Gibbs free energies differ by up to 15 kcal mol(-1) from the Gibbs free energies of model reactions with a constant number of protons. As for cysteine, calculations confirmed a strong preference for kappaS monodenate bonding in a broad pH range. The most stable product of the second reaction step, which proceeds from monodentate to chelate complex, is the kappa(2)S,N coordinated chelate. The reaction with methionine is more complex. In the first step all three considered methionine donor atoms (N, S and O) are thermodynamically preferred products depending on the platinum complex and the pH. This is in accordance with the experimental observation of a pH dependent migration between N and S donor atoms in a chemically related system. The most stable chelates of platinum with methionine are kappa(2)S,N and kappa(2)N,O bonded complexes. The comparison of reaction free energies of both amino acids suggests, that the bidentate methionine ligand can be displaced even by the monodentate cysteine ligand under certain conditions.
Follicular thyroid cancer avid on C-11 Methionine PET/CT

OpenAIRE

Jochumsen, Mads Ryø; Iversen, Peter; Arveschoug, Anne Kirstine

2018-01-01

Summary A case of follicular thyroid cancer with intense focal Methionine uptake on 11C-Methionine PET/CT is reported here. The use of 11C-Methionine PET in differentiated thyroid cancer is currently being investigated as a surrogate tracer compared to the more widely used 18F-FDG PET. This case illustrates the potential incremental value of this modality, not only in the localizing of parathyroid adenoma, but also indicating that 11C-Methionine PET might have a potential of increasing the pr...
Prediction of Methionine and Homocysteine levels in Zucker diabetic fatty (ZDF) rats as a T2DM animal model after consumption of a Methionine-rich diet

OpenAIRE

Han, Nayoung; Chae, Jung-woo; Jeon, Jihyun; Lee, Jaeyeon; Back, Hyun-moon; Song, Byungjeong; Kwon, Kwang-il; Kim, Sang Kyum; Yun, Hwi-yeol

2018-01-01

Background Although alterations in the methionine metabolism cycle (MMC) have been associated with vascular complications of diabetes, there have not been consistent results about the levels of methionine and homocysteine in type 2 diabetes mellitus (T2DM). The aim of the current study was to predict changes in plasma methionine and homocysteine concentrations after simulated consumption of methionine-rich foods, following the development of a mathematical model for MMC in Zucker Diabetic Fat...
The methionine salvage pathway in Bacillus subtilis

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Danchin Antoine

2002-04-01

Full Text Available Abstract Background Polyamine synthesis produces methylthioadenosine, which has to be disposed of. The cell recycles it into methionine through methylthioribose (MTR. Very little was known about MTR recycling for methionine salvage in Bacillus subtilis. Results Using in silico genome analysis and transposon mutagenesis in B. subtilis we have experimentally uncovered the major steps of the dioxygen-dependent methionine salvage pathway, which, although similar to that found in Klebsiella pneumoniae, recruited for its implementation some entirely different proteins. The promoters of the genes have been identified by primer extension, and gene expression was analyzed by Northern blotting and lacZ reporter gene expression. Among the most remarkable discoveries in this pathway is the role of an analog of ribulose diphosphate carboxylase (Rubisco, the plant enzyme used in the Calvin cycle which recovers carbon dioxide from the atmosphere as a major step in MTR recycling. Conclusions A complete methionine salvage pathway exists in B. subtilis. This pathway is chemically similar to that in K. pneumoniae, but recruited different proteins to this purpose. In particular, a paralogue or Rubisco, MtnW, is used at one of the steps in the pathway. A major observation is that in the absence of MtnW, MTR becomes extremely toxic to the cell, opening an unexpected target for new antimicrobial drugs. In addition to methionine salvage, this pathway protects B. subtilis against dioxygen produced by its natural biotope, the surface of leaves (phylloplane.
Acute Administration of Methionine Affects Performance of Swiss ...

African Journals Online (AJOL)

Acetylcholinesterase activities in all groups were not statistically significant. It can be concluded that acute methionine administration has some benefits in memory enhancement. However, a short course folate supplementation impairslearning and working memory especially when combined with methionine which may be ...
Methylated nucleosides in tRNA and tRNA methyltransferases

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Hiroyuki eHori

2014-05-01

Full Text Available To date, more than 90 modified nucleosides have been found in tRNA and the biosynthetic pathways of the majority of tRNA modifications include a methylation step(s. Recent studies of the biosynthetic pathways have demonstrated that the availability of methyl group donors for the methylation in tRNA is important for correct and efficient protein synthesis. In this review, I focus on the methylated nucleosides and tRNA methyltransferases. The primary functions of tRNA methylations are linked to the different steps of protein synthesis, such as the stabilization of tRNA structure, reinforcement of the codon–anticodon interaction, regulation of wobble base pairing, and prevention of frameshift errors. However, beyond these basic functions, recent studies have demonstrated that tRNA methylations are also involved in the RNA quality control system and regulation of tRNA localization in the cell. In a thermophilic eubacterium, tRNA modifications and the modification enzymes form a network that responses to temperature changes. Furthermore, several modifications are involved in genetic diseases, infections, and the immune response. Moreover, structural, biochemical, and bioinformatics studies of tRNA methyltransferases have been clarifying the details of tRNA methyltransferases and have enabled these enzymes to be classified. In the final section, the evolution of modification enzymes is discussed.
Extra-virgin olive oil contains a metabolo-epigenetic inhibitor of cancer stem cells

Science.gov (United States)

Corominas-Faja, Bruna; Cuyàs, Elisabet; Lozano-Sánchez, Jesús; Cufí, Sílvia; Verdura, Sara; Fernández-Arroyo, Salvador; Borrás-Linares, Isabel; Martin-Castillo, Begoña; Martin, Ángel G; Lupu, Ruth; Nonell-Canals, Alfons; Micol, Vicente; Joven, Jorge; Segura-Carretero, Antonio; Menendez, Javier A

2018-01-01

Abstract Targeting tumor-initiating, drug-resistant populations of cancer stem cells (CSC) with phytochemicals is a novel paradigm for cancer prevention and treatment. We herein employed a phenotypic drug discovery approach coupled to mechanism-of-action profiling and target deconvolution to identify phenolic components of extra virgin olive oil (EVOO) capable of suppressing the functional traits of CSC in breast cancer (BC). In vitro screening revealed that the secoiridoid decarboxymethyl oleuropein aglycone (DOA) could selectively target subpopulations of epithelial-like, aldehyde dehydrogenase (ALDH)-positive and mesenchymal-like, CD44+CD24−/low CSC. DOA could potently block the formation of multicellular tumorspheres generated from single-founder stem-like cells in a panel of genetically diverse BC models. Pretreatment of BC populations with noncytotoxic doses of DOA dramatically reduced subsequent tumor-forming capacity in vivo. Mice orthotopically injected with CSC-enriched BC-cell populations pretreated with DOA remained tumor-free for several months. Phenotype microarray-based screening pointed to a synergistic interaction of DOA with the mTOR inhibitor rapamycin and the DNA methyltransferase (DNMT) inhibitor 5-azacytidine. In silico computational studies indicated that DOA binds and inhibits the ATP-binding kinase domain site of mTOR and the S-adenosyl-l-methionine (SAM) cofactor-binding pocket of DNMTs. FRET-based Z-LYTE™ and AlphaScreen-based in vitro assays confirmed the ability of DOA to function as an ATP-competitive mTOR inhibitor and to block the SAM-dependent methylation activity of DNMTs. Our systematic in vitro, in vivo and in silico approaches establish the phenol-conjugated oleoside DOA as a dual mTOR/DNMT inhibitor naturally occurring in EVOO that functionally suppresses CSC-like states responsible for maintaining tumor-initiating cell properties within BC populations. PMID:29452350

Association of AS3MT polymorphisms and the risk of premalignant arsenic skin lesions

International Nuclear Information System (INIS)

Valenzuela, Olga L.; Drobna, Zuzana; Hernandez-Castellanos, Erika; Sanchez-Pena, Luz C.; Garcia-Vargas, Gonzalo G.; Borja-Aburto, Victor H.; Styblo, Miroslav; Del Razo, Luz M.

2009-01-01

Exposure to naturally occurring inorganic arsenic (iAs), primarily from contaminated drinking water, is considered one of the top environmental health threats worldwide. Arsenic (+3 oxidation state) methyltransferase (AS3MT) is the key enzyme in the biotransformation pathway of iAs. AS3MT catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to trivalent arsenicals, resulting in the production of methylated (MAs) and dimethylated arsenicals (DMAs). MAs is a susceptibility factor for iAs-induced toxicity. In this study, we evaluated the association of the polymorphism in AS3MT gene with iAs metabolism and with the presence of arsenic (As) premalignant skin lesions. This is a case-control study of 71 cases with skin lesions and 51 controls without skin lesions recruited from a iAs endemic area in Mexico. We measured urinary As metabolites, differentiating the trivalent and pentavalent arsenical species, using the hydride generation atomic absorption spectrometry. In addition, the study subjects were genotyped to analyze three single nucleotide polymorphisms (SNPs), A-477G, T14458C (nonsynonymus SNP; Met287Thr), and T35587C, in the AS3MT gene. We compared the frequencies of the AS3MT alleles, genotypes, and haplotypes in individuals with and without skin lesions. Marginal differences in the frequencies of the Met287Thr genotype were identified between individuals with and without premalignant skin lesions (p = 0.055): individuals carrying the C (TC+CC) allele (Thr) were at risk [odds ratio = 4.28; 95% confidence interval (1.0-18.5)]. Also, individuals with C allele of Met287Thr displayed greater percentage of MAs in urine and decrease in the percentage of DMAs. These findings indicate that Met287Thr influences the susceptibility to premalignant As skin lesions and might be at increased risk for other adverse health effects of iAs exposure.
Follicular thyroid cancer avid on C-11 Methionine PET/CT

Directory of Open Access Journals (Sweden)

Mads Ryø Jochumsen

2018-01-01

Full Text Available A case of follicular thyroid cancer with intense focal Methionine uptake on 11C-Methionine PET/CT is reported here. The use of 11C-Methionine PET in differentiated thyroid cancer is currently being investigated as a surrogate tracer compared to the more widely used 18F-FDG PET. This case illustrates the potential incremental value of this modality, not only in the localizing of parathyroid adenoma, but also indicating that 11C-Methionine PET might have a potential of increasing the pretest likelihood of thyroid malignancy in a cold nodule with highly increased Sestamibi uptake.
Refined global methyl halide budgets with respect to rapeseed (Brassica napus) by life-cycle measurements

Science.gov (United States)

Jiao, Y.; Acdan, J.; Xu, R.; Deventer, M. J.; Rhew, R. C.

2017-12-01

A precise quantification of global methyl halide budgets is needed to evaluate the ozone depletion potential of these compounds and to predict future changes of stratospheric ozone. However, the global budgets of methyl halides are not balanced between currently identified and quantified sources and sinks. Our study re-evaluated the methyl bromide budget from global cultivated rapeseed (Brassica napus) through life-cycle flux measurements both in the greenhouse and in the field, yielding a methyl bromide emission rate that scales globally to 1.0 - 1.2 Gg yr-1. While this indicates a globally significant source, it is much smaller than the previously widely cited value of 5 - 6 Gg yr-1(Mead et al., 2008), even taking into account the near tripling of annual global yield of rapeseed since the previous evaluation was conducted. Our study also evaluated the methyl chloride and methyl iodide emission levels from rapeseed, yielding emission rates that scale to 5.4 Gg yr-1 for methyl chloride and 1.8 Gg yr-1 of methyl iodide. The concentrations of the methyl donor SAM (S-adenosyl methionine) and the resultant product SAH (S-Adenosyl-L-homocysteine) were also analyzed to explore their role in biogenic methyl halide formation. Halide gradient incubations showed that the magnitude of methyl halide emissions from rapeseed is highly correlated to soil halide levels, thus raising the concern that the heterogeneity of soil halide contents geographically should be considered when extrapolating to global budget.
Comparative efficacy of herbal and synthetic methionine on ...

African Journals Online (AJOL)

HM) compared to synthetic methionine (SM) in the diets of domestic laying hens. The herbal methionine (Meth-o-Tas®) was supplied by Intas Pharmaceutical Limited, India. The HM and SM were added to a standard diet at 0.5 and 1.0 kg per ...
Haematological and Serum Biochemical Parameters of Broiler Chickens Fed Varying Dietary Levels of Fermented Castor Oil Seed Meal (Ricinus communis L. and Different Methionine Sources in South Western Nigeria

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Ayorinde David Adeniran

2017-09-01

Full Text Available In this experiment, the effect of varying dietary levels of fermented castor oil seed meal (FCSM and different methionine sources (DL-methionine and herbal methionine on haematological and serum biochemical parameters of broilers. A total of 240 one-day-old Anak broiler chicks were used in the experiment lasted 56 days. The dietary experiment was laid out as a completely randomized design in a 4 × 2 factorial arrangement consisting of 4 dietary levels of FCSM (0, 50, 100 and 150 g/kg and 2 methionine sources (DL-methionine and herbal methionine. The birds were weighed and randomly distributed into 8 treatments with 3 replicates of 10 birds each. During the starter phase of the experiment, haemoglobin, red blood cell count, mean corpuscular haemoglobin concentration and eosinophil counts were higher (P
Influence of dietary methionine on the metabolism of selenomethionine in rats

International Nuclear Information System (INIS)

Butler, J.A.; Beilstein, M.A.; Whanger, P.D.

1989-01-01

To determine the influence of methionine on selenomethionine (SeMet) metabolism, weanling male rats were fed for 8 wk a basal diet marginally deficient in sulfur amino acids, containing 2.0 micrograms selenium (Se)/g as DL-SeMet and supplemented with 0, 0.3, 0.6 or 1.2% DL-methionine. Increased dietary methionine caused decreased selenium deposition in all tissues examined but increased glutathione peroxidase activity in testes, liver and lungs. A positive correlation was found between dietary methionine and the calculated percentage of selenium associated with GSHPx. In a second experiment, 75 SeMet was injected into weanling male rats which had been fed the basal diet containing 2.0 micrograms selenium as DL-SeMet with or without the addition of 1.0% methionine. The selenoamino acid content of tissues and the distribution of 75 Se in erythrocyte proteins were determined. In comparison to the rats fed the basal diet without added methionine, significantly more 75 Se-selenocysteine was found in liver and muscle, more 75 Se was found in erythrocyte GSHPx and less 75 Se was found in erythrocyte hemoglobin of rats fed 1.0% methionine. These data suggest that methionine diverts SeMet from incorporation into general proteins and enhances its conversion to selenocysteine for specific selenium-requiring proteins, such as GSHPx
Effects of methionine supplementation on the expression of protein deposition-related genes in acute heat stress-exposed broilers.

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Ana Paula Del Vesco

Full Text Available The objective of this study was to evaluate the effect of heat stress and methionine supplementation on the gene expression of insulin-like growth factor I (IGF-I, growth hormone receptor (GHR, phosphatidylinositol 3-kinase, and regulatory 1 (PI3KR1 in the liver, as well as the expression of the atrogin 1 and cathepsin L2 (CTSL2 genes in the breast muscle of broilers. Broilers from 1-21 and 22-42 days of age were divided into three treatments related to methionine supplementation as follows: without methionine supplementation (MD, recommended level of methionine (DL1, and excess supplementation of methionine (DL2. The animals were either maintained at a thermal comfort temperature or exposed to heat stress (HS (38°C for 24 hours, starting on day 20 or day 41 for experiments 1 and 2, respectively. The heat stress increased the body temperature at both ages. Starter period: The HS animals presented increased plasma creatinine content (P<0.0001 and the highest CTSL2 gene expression (P<0.0001. The methionine supplementation increased the IGF-I (P = 0.0144 and GHR (P = 0.0011 gene expression and decreased the CTSL2 (P = 0.0004 and atrogin 1 (P = 0.0012 gene expression. Grower period: Significant effects for the interaction between supplementation and environment were observed for GHR (P = 0.0252 and CTSL2 (P = 0.0011 gene expression. The highest GHR expression was observed in animals that remained in thermal comfort on the DL2 diet, and the lowest expression occurred in the HS animals fed the MD diet. For CTSL2, the HS animals fed the MD diet presented the highest CTSL2 gene expression, and the lowest expression was observed in the animals maintained at thermal comfort on DL1 and DL2 diets. Only methionine supplementation had effect on atrogin-1 gene expression (P<0.0001, with higher methionine content in the diet lower atrogin-1 gene expression was observed. Our results suggest that heat stress induces greater protein degradation and that
Method for the typing of Clostridium difficile based on polyacrylamide gel electrophoresis of (/sup 35/S)methionine-labeled proteins

Energy Technology Data Exchange (ETDEWEB)

Tabaqchali, S.; O' Farrell, S.; Holland, D.; Silman, R.

1986-01-01

A typing method for Clostridium difficile based on the incorporation of (/sup 35/S)methionine into cellular proteins, their separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their visualization by autoradiography is described. On analysis of the radiolabeled-protein profiles, nine distinct groups were observed (A to E and W to Z). The method, which is simple, reproducible, and readily expandable, has been applied in epidemiological studies to demonstrate cross-infection and hospital acquisition of C. difficile.
Cellular content and biosynthesis of polyamines during rooster spermatogenesis.

Science.gov (United States)

Oliva, R; Vidal, S; Mezquita, C

1982-01-01

The natural polyamines spermine and spermidine, and the diamine putrescine, were extracted from rooster testis cells separated by sedimentation at unit gravity, and from vas-deferens spermatozoa. The ratios spermine/DNA and spermidine/DNA were kept relatively constant throughout spermatogenesis, whereas the ratio putrescine/DNA rose in elongated spermatids. The cellular content of spermine, spermidine and putrescine decreased markedly in mature spermatozoa. Two rate-limiting enzymes in the biosynthetic pathway of polyamines, ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase, showed their highest activities at the end of spermiogenesis and were not detectable in vas-deferens spermatozoa. A marked reduction in cell volume during spermiogenesis without a parallel decrease in the cellular content of polyamines suggests the possibility that the marked changes in chromatin composition and structure occurring in rooster late spermatids could take place in an ambience of high polyamine concentration. Images PLATE 1 PMID:7159401
Floral Benzenoid Carboxyl Methyltransferases: From in Vitro to in Planta Function

Energy Technology Data Exchange (ETDEWEB)

Effmert,U.; Saschenbrecker, S.; Ross, J.; Negre, F.; Fraser, C.; Noel, J.; Dudareva, N.; Piechulla, B.

2005-01-01

Benzenoid carboxyl methyltransferases synthesize methyl esters (e.g., methyl benzoate and methyl salicylate), which are constituents of aromas and scents of many plant species and play important roles in plant communication with the surrounding environment. Within the past five years, eleven such carboxyl methyltransferases were isolated and most of them were comprehensively investigated at the biochemical, molecular and structural level. Two types of enzymes can be distinguished according to their substrate preferences: the SAMT-type enzymes isolated from Clarkia breweri, Stephanotis floribunda, Antirrhinum majus, Hoya carnosa, and Petunia hybrida, which have a higher catalytic efficiency and preference for salicylic acid, while BAMT-type enzymes from A. majus, Arabidopsis thaliana, Arabidopsis lyrata, and Nicotiana suaveolens prefer benzoic acid. The elucidation of C. breweri SAMT's three-dimensional structure allowed a detailed modelling of the active sites of the carboxyl methyltransferases and revealed that the SAM binding pocket is highly conserved among these enzymes while the methyl acceptor binding site exhibits some variability, allowing a classification into SAMT-type and BAMT-type enzymes. The analysis of expression patterns coupled with biochemical characterization showed that these carboxyl methyltransferases are involved either in floral scent biosynthesis or in plant defense responses. While the latter can be induced by biotic or abiotic stress, the genes responsible for floral scent synthesis exhibit developmental and rhythmic expression pattern. The nature of the product and efficiency of its formation in plants depend on the availability of substrates, the catalytic efficiency of the enzyme toward benzoic acid and/or salicylic acid, and the transcriptional, translational, and post-translational regulation at the enzyme level. The biochemical properties of benzenoid carboxyl methyltransferases suggest that the genes involved in plant defenses
Recruitment of DNA methyltransferase I to DNA repair sites

Science.gov (United States)

Mortusewicz, Oliver; Schermelleh, Lothar; Walter, Joachim; Cardoso, M. Cristina; Leonhardt, Heinrich

2005-01-01

In mammalian cells, the replication of genetic and epigenetic information is directly coupled; however, little is known about the maintenance of epigenetic information in DNA repair. Using a laser microirradiation system to introduce DNA lesions at defined subnuclear sites, we tested whether the major DNA methyltransferase (Dnmt1) or one of the two de novo methyltransferases (Dnmt3a, Dnmt3b) are recruited to sites of DNA repair in vivo. Time lapse microscopy of microirradiated mammalian cells expressing GFP-tagged Dnmt1, Dnmt3a, or Dnmt3b1 together with red fluorescent protein-tagged proliferating cell nuclear antigen (PCNA) revealed that Dnmt1 and PCNA accumulate at DNA damage sites as early as 1 min after irradiation in S and non-S phase cells, whereas recruitment of Dnmt3a and Dnmt3b was not observed. Deletion analysis showed that Dnmt1 recruitment was mediated by the PCNA-binding domain. These data point to a direct role of Dnmt1 in the restoration of epigenetic information during DNA repair. PMID:15956212
Identification of an S-adenosylmethionine (SAM) dependent arsenic methyltransferase in Danio rerio

Energy Technology Data Exchange (ETDEWEB)

Hamdi, Mohamad [Department of Biological Sciences, Oakland University, Rochester, MI 48309 (United States); Yoshinaga, Masafumi; Packianathan, Charles; Qin, Jie [Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, FL33199 (United States); Hallauer, Janell; McDermott, Joseph R. [Department of Biological Sciences, Oakland University, Rochester, MI 48309 (United States); Yang, Hung-Chi [Department of Medical Biotechnology and Laboratory Sciences, Chang-Gung University, Tao-Yuan, Kwei-San 333, Taiwan (China); Tsai, Kan-Jen [School of Medical Laboratory and Biotechnology, Chung Shan Medical University, Taichung, Taiwan (China); Liu, Zijuan, E-mail: liu2345@oakland.edu [Department of Biological Sciences, Oakland University, Rochester, MI 48309 (United States)

2012-07-15

Arsenic methylation is an important cellular metabolic process that modulates arsenic toxicity and carcinogenicity. Biomethylation of arsenic produces a series of mono-, di- and tri-methylated arsenic metabolites that can be detected in tissues and excretions. Here we report that zebrafish exposed to arsenite (As{sup III}) produces organic arsenicals, including MMA{sup III}, MMA{sup V} and DMA{sup V} with characteristic tissue ratios, demonstrating that an arsenic methylation pathway exists in zebrafish. In mammals, cellular inorganic arsenic is methylated by a SAM-dependent arsenic methyltransferase, AS3MT. A zebrafish arsenic methyltransferase homolog, As3mt, was identified by sequence alignment. Western blotting analysis showed that As3mt was universally expressed in zebrafish tissues. Prominent expression in liver and intestine correlated with methylated arsenic metabolites detected in those tissues. As3mt was expressed in and purified from Escherichia coli for in vitro functional studies. Our results demonstrated that As3mt methylated As{sup III} to DMA{sup V} as an end product and produced MMA{sup III} and MMA{sup V} as intermediates. The activity of As3mt was inhibited by elevated concentrations of the substrate As{sup III} as well as the metalloid selenite, which is a well-known antagonistic micronutrient of arsenic toxicity. The activity As3mt was abolished by substitution of either Cys160 or Cys210, which corresponds to conserved cysteine residues in AS3MT homologs, suggesting that they are involved in catalysis. Expression in zebrafish of an enzyme that has a similar function to human and rodent orthologs in catalyzing intracellular arsenic biomethylation validates the applicability of zebrafish as a valuable vertebrate model for understanding arsenic-associated diseases in humans. -- Highlights: ► Zebrafish methylated As{sup III} to MMA{sup III}, MMA{sup V} and DMA{sup V}. ► A zebrafish arsenic methyltransferase (As3mt) was purified in E. coli. �
Homocysteine regulates fatty acid and lipid metabolism in yeast.

Science.gov (United States)

Visram, Myriam; Radulovic, Maja; Steiner, Sabine; Malanovic, Nermina; Eichmann, Thomas O; Wolinski, Heimo; Rechberger, Gerald N; Tehlivets, Oksana

2018-04-13

S -Adenosyl-l-homocysteine hydrolase (AdoHcy hydrolase; Sah1 in yeast/AHCY in mammals) degrades AdoHcy, a by-product and strong product inhibitor of S -adenosyl-l-methionine (AdoMet)-dependent methylation reactions, to adenosine and homocysteine (Hcy). This reaction is reversible, so any elevation of Hcy levels, such as in hyperhomocysteinemia (HHcy), drives the formation of AdoHcy, with detrimental consequences for cellular methylation reactions. HHcy, a pathological condition linked to cardiovascular and neurological disorders, as well as fatty liver among others, is associated with a deregulation of lipid metabolism. Here, we developed a yeast model of HHcy to identify mechanisms that dysregulate lipid metabolism. Hcy supplementation to wildtype cells up-regulated cellular fatty acid and triacylglycerol content and induced a shift in fatty acid composition, similar to changes observed in mutants lacking Sah1. Expression of the irreversible bacterial pathway for AdoHcy degradation in yeast allowed us to dissect the impact of AdoHcy accumulation on lipid metabolism from the impact of elevated Hcy. Expression of this pathway fully suppressed the growth deficit of sah1 mutants as well as the deregulation of lipid metabolism in both the sah1 mutant and Hcy-exposed wildtype, showing that AdoHcy accumulation mediates the deregulation of lipid metabolism in response to elevated Hcy in yeast. Furthermore, Hcy supplementation in yeast led to increased resistance to cerulenin, an inhibitor of fatty acid synthase, as well as to a concomitant decline of condensing enzymes involved in very long-chain fatty acid synthesis, in line with the observed shift in fatty acid content and composition. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.
Genetic basis of metabolome variation in yeast.

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Jeffrey S Breunig

2014-03-01

Full Text Available Metabolism, the conversion of nutrients into usable energy and biochemical building blocks, is an essential feature of all cells. The genetic factors responsible for inter-individual metabolic variability remain poorly understood. To investigate genetic causes of metabolome variation, we measured the concentrations of 74 metabolites across ~ 100 segregants from a Saccharomyces cerevisiae cross by liquid chromatography-tandem mass spectrometry. We found 52 quantitative trait loci for 34 metabolites. These included linkages due to overt changes in metabolic genes, e.g., linking pyrimidine intermediates to the deletion of ura3. They also included linkages not directly related to metabolic enzymes, such as those for five central carbon metabolites to ira2, a Ras/PKA pathway regulator, and for the metabolites, S-adenosyl-methionine and S-adenosyl-homocysteine to slt2, a MAP kinase involved in cell wall integrity. The variant of ira2 that elevates metabolite levels also increases glucose uptake and ethanol secretion. These results highlight specific examples of genetic variability, including in genes without prior known metabolic regulatory function, that impact yeast metabolism.
21 CFR 582.5477 - Methionine hydroxy analog and its calcium salts.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Methionine hydroxy analog and its calcium salts... Nutrients and/or Dietary Supplements 1 § 582.5477 Methionine hydroxy analog and its calcium salts. (a) Product. Methionine hydroxy analog and its calcium salts. (b) [Reserved] (c) Limitations, restrictions, or...
Differential identification of Candida species and other yeasts by analysis of [35S]methionine-labeled polypeptide profiles

International Nuclear Information System (INIS)

Shen, H.D.; Choo, K.B.; Tsai, W.C.; Jen, T.M.; Yeh, J.Y.; Han, S.H.

1988-01-01

This paper describes a scheme for differential identification of Candida species and other yeasts based on autoradiographic analysis of protein profiles of [ 35 S]methionine-labeled cellular proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Using ATCC strains as references, protein profile analysis showed that different Candida and other yeast species produced distinctively different patterns. Good agreement in results obtained with this approach and with other conventional systems was observed. Being accurate and reproducible, this approach provides a basis for the development of an alternative method for the identification of yeasts isolated from clinical specimens
Molecular Basis for the Regulation of the H3K4 Methyltransferase Activity of PRDM9

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Hong Wu

2013-10-01

Full Text Available PRDM9, a histone lysine methyltransferase, is a key determinant of the localization of meiotic recombination hot spots in humans and mice and the only vertebrate protein known to be involved in hybrid sterility. Here, we report the crystal structure of the PRDM9 methyltransferase domain in complex with a histone H3 peptide dimethylated on lysine 4 (H3K4me2 and S-adenosylhomocysteine (AdoHcy, which provides insights into the methyltransferase activity of PRDM proteins. We show that the genuine substrate of PRDM9 is histone H3 lysine 4 (H3K4 and that the enzyme possesses mono-, di-, and trimethylation activities. We also determined the crystal structure of PRDM9 in its autoinhibited state, which revealed a rearrangement of the substrate and cofactor binding sites by a concerted action of the pre-SET and post-SET domains, providing important insights into the regulatory mechanisms of histone lysine methyltransferase activity.
Variability of plasma and urine betaine in diabetes mellitus and its relationship to methionine load test responses: an observational study

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Lever Michael

2012-07-01

Full Text Available Abstract Background Since betaine is an osmolyte and methyl donor, and abnormal betaine loss is common in diabetes mellitus (>20% patients, we investigated the relationship between betaine and the post-methionine load rise in homocysteine, in diabetes and control subjects. The post-methionine load test is reported to be both an independent vascular risk factor and a measure of betaine sufficiency. Methods Patients with type 2 diabetes (n = 34 and control subjects (n = 17 were recruited. We measured baseline fasting plasma and 4-hour post-methionine load (L-methionine, 0.1 mg/kg body weight concentrations of homocysteine, betaine, and the betaine metabolite N,N-dimethylglycine. Baseline urine excretions of betaine, dimethylglycine and glucose were measured on morning urine samples as the ratio to urine creatinine. Statistical determinants of the post-methionine load increase in homocysteine were identified in multiple linear regression models. Results Plasma betaine concentrations and urinary betaine excretions were significantly (p p = 0.00014 and plasma dimethylglycine concentrations (p = 0.039 were also more variable. In diabetes, plasma betaine was a significant negative determinant (p Conclusions Both high and low plasma betaine concentrations, and high and low urinary betaine excretions, are more prevalent in diabetes. The availability of betaine affects the response in the methionine load test. The benefits of increasing betaine intake should be investigated.
A methionine-free diet associated with nitrosourea treatment down-regulates methylguanine-DNA methyl transferase activity in patients with metastatic cancer.

Science.gov (United States)

Thivat, Emilie; Durando, Xavier; Demidem, Aïcha; Farges, Marie-Chantal; Rapp, Maryse; Cellarier, Eric; Guenin, Samuel; D'Incan, Michel; Vasson, Marie-Paule; Chollet, Philippe

2007-01-01

Methionine (MET) depletion used in association with chemotherapy improves the therapeutic index in animal models. This potentiating effect may be due to tumor cell sensitization to chloroethylnitrosoureas through their MET dependency and the down-regulation of O6- methylguanine-DNA methyltransferase (MGMT). Our purpose was to evaluate the impact of the association of a dietary MET restriction with nitrosourea treatment on MGMT activity in peripheral blood mononuclear cells (PBMCs). Six patients with metastatic cancer (melanoma and glioma) received 4 cycles of a MET-free diet with cystemustine (60 mg/m2). MGMT activity in PBMCs decreased by an average of 13% from 553+/-90 fnol/mg before the diet to 413+/-59 fmol/mg after the diet + chemotherapy period (p=0.029). The decrease of MGMT activity was not affected by the duration of the MET-free diet period but seems to be correlated to the plasma MET depletion induced by the MET-free diet.
A mouse speciation gene encodes a meiotic histone H3 methyltransferase

Czech Academy of Sciences Publication Activity Database

Mihola, Ondřej; Trachtulec, Zdeněk; Vlček, Čestmír; Schimenti, J.C.; Forejt, Jiří

2009-01-01

Roč. 323, č. 5912 (2009), s. 373-375 ISSN 0036-8075 Institutional research plan: CEZ:AV0Z50520514 Keywords : hybrid sterility * histone H3K4 methyltransferase * Prdm9 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 29.747, year: 2009

Structural Chemistry of Human RNA Methyltransferases.

Science.gov (United States)

Schapira, Matthieu

2016-03-18

RNA methyltransferases (RNMTs) play important roles in RNA stability, splicing, and epigenetic mechanisms. They constitute a promising target class that is underexplored by the medicinal chemistry community. Information of relevance to drug design can be extracted from the rich structural coverage of human RNMTs. In this work, the structural chemistry of this protein family is analyzed in depth. Unlike most methyltransferases, RNMTs generally feature a substrate-binding site that is largely open on the cofactor-binding pocket, favoring the design of bisubstrate inhibitors. Substrate purine or pyrimidines are often sandwiched between hydrophobic walls that can accommodate planar ring systems. When the substrate base is laying on a shallow surface, a 5' flanking base is sometimes anchored in a druggable cavity. The cofactor-binding site is structurally more diverse than in protein methyltransferases and more druggable in SPOUT than in Rossman-fold enzymes. Finally, conformational plasticity observed both at the substrate and cofactor binding sites may be a challenge for structure-based drug design. The landscape drawn here may inform ongoing efforts toward the discovery of the first human RNMT inhibitors.
Methionine metabolism in piglets Fed DL-methionine or its hydroxy analogue was affected by distribution of enzymes oxidizing these sources to keto-methionine.

Science.gov (United States)

Fang, Zhengfeng; Luo, Hefeng; Wei, Hongkui; Huang, Feiruo; Qi, Zhili; Jiang, Siwen; Peng, Jian

2010-02-10

Previous evidence shows that the extensive catabolism of dietary essential amino acids (AA) by the intestine results in decreased availability of these AA for protein synthesis in extraintestinal tissues. This raises the possibility that extraintestinal availability of AA may be improved by supplying the animal with an AA source more of which can bypass the intestine. To test this hypothesis, six barrows (35-day-old, 8.6 +/- 1.4 kg), implanted with arterial, portal, and mesenteric catheters, were fed a DL-methionine (DL-MET) or DL-2-hydroxy-4-methylthiobutyrate (DL-HMTB) diet once hourly and infused intramesenterically with 1% p-amino hippurate. Although the directly available L-MET in DL-MET diet was about 1.2-fold that in DL-HMTB diet, the net portal appearance of L-MET was not different between the two diets. Compared with the low mRNA abundance and low activity of D-2-hydroxy acid dehydrogenase (D-HADH) and l-2-hydroxy acid oxidase (L-HAOX) in the intestine, the high mRNA abundance and high activity of D-AA oxidase (D-AAOX) indicated that the intestine had a relatively higher capacity of D-MET utilization than of dl-HMTB utilization to L-MET synthesis and its subsequent metabolism. However, in contrast to the much lower D-AAOX activity (nmol/g tissue) in the stomach than in the liver and kidney, both d-HADH and L-HAOX activity in the stomach was comparable with those in the liver and/or kidney, indicating the substantial capacity of the stomach to convert DL-HMTB to L-MET. Collectively, the difference in distribution of activity and mRNA abundance of D-AAOX, D-HADH, and L-HAOX in the piglets may offer a biological basis for the similar portal appearance of L-MET between DL-MET and DL-HMTB diets, and thus may provide new important insights into nutritional efficiency of different L-MET sources.
Chemical Probes of Histone Lysine Methyltransferases

Science.gov (United States)

2015-01-01

Growing evidence suggests that histone methyltransferases (HMTs, also known as protein methyltransferases (PMTs)) play an important role in diverse biological processes and human diseases by regulating gene expression and the chromatin state. Therefore, HMTs have been increasingly recognized by the biomedical community as a class of potential therapeutic targets. High quality chemical probes of HMTs, as tools for deciphering their physiological functions and roles in human diseases and testing therapeutic hypotheses, are critical for advancing this promising field. In this review, we focus on the discovery, characterization, and biological applications of chemical probes for HMTs. PMID:25423077
Leucine 208 in human histamine N-methyltransferase emerges as a hotspot for protein stability rationalizing the role of the L208P variant in intellectual disability.

Science.gov (United States)

Tongsook, Chanakan; Niederhauser, Johannes; Kronegger, Elena; Straganz, Grit; Macheroux, Peter

2017-01-01

The degradation of histamine catalyzed by the SAM-dependent histamine N-methyltransferase (HNMT) is critically important for the maintenance of neurological processes. Recently, two mutations in the encoding human gene were reported to give rise to dysfunctional protein variants (G60D and L208P) leading to intellectual disability. In the present study, we have expressed eight L208 variants with either apolar (L208F and L208V), polar (L208N and L208T) or charged (L208D, L208H, L208K and L208R) amino acids to define the impact of side chain variations on protein structure and function. We found that the variants L208N, L208T, L208D and L208H were severely compromised in their stability. The other four variants were obtained in lower amounts in the order wild-type HNMT>L208F=L208V>L208K=L208R. Biochemical characterization of the two variants L208F and L208V exhibited similar Michaelis-Menten parameters for SAM and histamine while the enzymatic activity was reduced to 21% and 48%, respectively. A substantial loss of enzymatic activity and binding affinity for histamine was seen for the L208K and L208R variants. Similarly the thermal stability for the latter variants was reduced by 8 and 13°C, respectively. These findings demonstrate that position 208 is extremely sensitive to side chain variations and even conservative replacements affect enzymatic function. Molecular dynamics simulations showed that amino acid replacements in position 208 perturb the helical character and disrupt interactions with the adjacent β-strand, which is involved in the binding and correct positioning of histamine. This finding rationalizes the gradual loss of enzymatic activity observed in the L208 variants. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.
Placentome Nutrient Transporters and Mammalian Target of Rapamycin Signaling Proteins Are Altered by the Methionine Supply during Late Gestation in Dairy Cows and Are Associated with Newborn Birth Weight.

Science.gov (United States)

Batistel, Fernanda; Alharthi, Abdulrahman Sm; Wang, Ling; Parys, Claudia; Pan, Yuan-Xiang; Cardoso, Felipe C; Loor, Juan J

2017-09-01

Background: To our knowledge, most research demonstrating a link between maternal nutrition and both fetal growth and offspring development after birth has been performed with nonruminants. Whether such relationships exist in large ruminants is largely unknown. Objective: We aimed to investigate whether increasing the methionine supply during late pregnancy would alter uteroplacental tissue nutrient transporters and mammalian target of rapamycin (mTOR) and their relation with newborn body weight. Methods: Multiparous Holstein cows were used in a randomized complete block design experiment. During the last 28 d of pregnancy, cows were fed a control diet or the control diet plus ethylcellulose rumen-protected methionine (0.9 g/kg dry matter intake) (Mepron; Evonik Nutrition & Care GmbH) to achieve a 2.8:1 ratio of lysine to methionine in the metabolizable protein reaching the small intestine. We collected placentome samples at parturition and used them to assess mRNA and protein expression and the phosphorylation status of mTOR pathway proteins. Results: Newborn body weight was greater in the methionine group than in the control group (44.1 kg and 41.8 kg, respectively; P ≤ 0.05). Increasing the methionine supply also resulted in greater feed intake (15.8 kg/d and 14.6 kg/d), plasma methionine (11.9 μM and 15.3 μM), and plasma insulin (1.16 μg/L and 0.81 μg/L) in cows during late pregnancy. As a result, mRNA expression of genes involved in neutral amino acid transport [solute carrier (SLC) family members SLC3A2 , SLC7A5 , SLC38A1 , and SLC38A10 ], glucose transport [ SLC2A1 , SLC2A3 , and SLC2A4 ], and the mTOR pathway [mechanistic target of rapamycin and ribosomal protein S6 kinase B1] were upregulated ( P ≤ 0.07) in methionine-supplemented cows. Among 6 proteins in the mTOR pathway, increasing the methionine supply led to greater ( P ≤ 0.09) protein expression of α serine-threonine kinase (AKT), phosphorylated (p)-AKT, p-eukaryotic elongation factor 2
Polymorphisms in O-methyltransferase genes are associated with stover cell wall digestibility in European maize (Zea mays L.)

DEFF Research Database (Denmark)

Brenner, Everton A; Zein, Imad; Chen, Yongsheng

2010-01-01

Background OMT (O-methyltransferase) genes are involved in lignin biosynthesis, which relates to stover cell wall digestibility. Reduced lignin content is an important determinant of both forage quality and ethanol conversion efficiency of maize stover. Results Variation in genomic sequences codi...
Preliminary X-ray analysis of twinned crystals of sarcosine dimethylglycine methyltransferase from Halorhodospira halochoris

International Nuclear Information System (INIS)

Kallio, Juha Pekka; Jänis, Janne; Nyyssölä, Antti; Hakulinen, Nina; Rouvinen, Juha

2009-01-01

The crystallization and preliminary X-ray diffraction analysis of sarcosine dimethylglycine methyltransferase from H. halochoris is reported. Sarcosine dimethylglycine methyltransferase (EC 2.1.1.157) is an enzyme from the extremely halophilic anaerobic bacterium Halorhodospira halochoris. This enzyme catalyzes the twofold methylation of sarcosine to betaine, with S-adenosylmethionine (AdoMet) as the methyl-group donor. This study presents the crystallization and preliminary X-ray analysis of recombinant sarcosine dimethylglycine methyltransferase produced in Escherichia coli. Mass spectroscopy was used to determine the purity and homogeneity of the enzyme material. Two different crystal forms, which initially appeared to be hexagonal and tetragonal, were obtained. However, on analyzing the diffraction data it was discovered that both crystal forms were pseudo-merohedrally twinned. The true crystal systems were monoclinic and orthorhombic. The monoclinic crystal diffracted to a maximum of 2.15 Å resolution and the orthorhombic crystal diffracted to 1.8 Å resolution
Why Nature Uses Radical SAM Enzymes so Widely: Electron Nuclear Double Resonance Studies of Lysine 2,3-Aminomutase Show the 5'-dAdo• "Free Radical" Is Never Free.

Science.gov (United States)

Horitani, Masaki; Byer, Amanda S; Shisler, Krista A; Chandra, Tilak; Broderick, Joan B; Hoffman, Brian M

2015-06-10

Lysine 2,3-aminomutase (LAM) is a radical S-adenosyl-L-methionine (SAM) enzyme and, like other members of this superfamily, LAM utilizes radical-generating machinery comprising SAM anchored to the unique Fe of a [4Fe-4S] cluster via a classical five-membered N,O chelate ring. Catalysis is initiated by reductive cleavage of the SAM S-C5' bond, which creates the highly reactive 5'-deoxyadenosyl radical (5'-dAdo•), the same radical generated by homolytic Co-C bond cleavage in B12 radical enzymes. The SAM surrogate S-3',4'-anhydroadenosyl-L-methionine (anSAM) can replace SAM as a cofactor in the isomerization of L-α-lysine to L-β-lysine by LAM, via the stable allylic anhydroadenosyl radical (anAdo•). Here electron nuclear double resonance (ENDOR) spectroscopy of the anAdo• radical in the presence of (13)C, (2)H, and (15)N-labeled lysine completes the picture of how the active site of LAM from Clostridium subterminale SB4 "tames" the 5'-dAdo• radical, preventing it from carrying out harmful side reactions: this "free radical" in LAM is never free. The low steric demands of the radical-generating [4Fe-4S]/SAM construct allow the substrate target to bind adjacent to the S-C5' bond, thereby enabling the 5'-dAdo• radical created by cleavage of this bond to react with its partners by undergoing small motions, ∼0.6 Å toward the target and ∼1.5 Å overall, that are controlled by tight van der Waals contact with its partners. We suggest that the accessibility to substrate and ready control of the reactive C5' radical, with "van der Waals control" of small motions throughout the catalytic cycle, is common within the radical SAM enzyme superfamily and is a major reason why these enzymes are the preferred means of initiating radical reactions in nature.
Partitioning of One-Carbon Units in Folate and Methionine Metabolism Is Essential for Neural Tube Closure

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Kit-Yi Leung

2017-11-01

Full Text Available Summary: Abnormal folate one-carbon metabolism (FOCM is implicated in neural tube defects (NTDs, severe malformations of the nervous system. MTHFR mediates unidirectional transfer of methyl groups from the folate cycle to the methionine cycle and, therefore, represents a key nexus in partitioning one-carbon units between FOCM functional outputs. Methionine cycle inhibitors prevent neural tube closure in mouse embryos. Similarly, the inability to use glycine as a one-carbon donor to the folate cycle causes NTDs in glycine decarboxylase (Gldc-deficient embryos. However, analysis of Mthfr-null mouse embryos shows that neither S-adenosylmethionine abundance nor neural tube closure depend on one-carbon units derived from embryonic or maternal folate cycles. Mthfr deletion or methionine treatment prevents NTDs in Gldc-null embryos by retention of one-carbon units within the folate cycle. Overall, neural tube closure depends on the activity of both the methionine and folate cycles, but transfer of one-carbon units between the cycles is not necessary. : Leung at al. find that embryonic neural tube closure depends both on the supply of one-carbon units to the folate cycle from glycine cleavage and on the methionine cycle. In contrast, transfer of one-carbon units from the folate cycle to the methionine cycle by MTHFR is dispensable. Keywords: one-carbon metabolism, folic acid, neural tube defects, spina bifida, glycine cleavage system, non-ketotic hyperglycinemia, eye, Mthfr, Gldc
Folate (vitamin B9) and vitamin B12 and their function in the maintenance of nuclear and mitochondrial genome integrity

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Fenech, Michael, E-mail: michael.fenech@csiro.au [CSIRO Food and Nutritional Sciences, PO Box 10041 Adelaide BC, SA 5000 (Australia)

2012-05-01

Folate plays a critical role in the prevention of uracil incorporation into DNA and hypomethylation of DNA. This activity is compromised when vitamin B12 concentration is low because methionine synthase activity is reduced, lowering the concentration of S-adenosyl methionine (SAM) which in turn may diminish DNA methylation and cause folate to become unavailable for the conversion of dUMP to dTMP. The most plausible explanation for the chromosome-breaking effect of low folate is excessive uracil misincorporation into DNA, a mutagenic lesion that leads to strand breaks in DNA during repair. Both in vitro and in vivo studies with human cells clearly show that folate deficiency causes expression of chromosomal fragile sites, chromosome breaks, excessive uracil in DNA, micronucleus formation, DNA hypomethylation and mitochondrial DNA deletions. In vivo studies show that folate and/or vitamin B12 deficiency and elevated plasma homocysteine (a metabolic indicator of folate deficiency) are significantly correlated with increased micronucleus formation and reduced telomere length respectively. In vitro experiments indicate that genomic instability in human cells is minimised when folic acid concentration in culture medium is greater than 100 nmol/L. Intervention studies in humans show (a) that DNA hypomethylation, chromosome breaks, uracil incorporation and micronucleus formation are minimised when red cell folate concentration is greater than 700 nmol/L and (b) micronucleus formation is minimised when plasma concentration of vitamin B12 is greater than 300 pmol/L and plasma homocysteine is less than 7.5 {mu}mol/L. These concentrations are achievable at intake levels at or above current recommended dietary intakes of folate (i.e. >400 {mu}g/day) and vitamin B12 (i.e. >2 {mu}g/day) depending on an individual's capacity to absorb and metabolise these vitamins which may vary due to genetic and epigenetic differences.
Crystal growth, structural, spectral, thermal, dielectric, linear and nonlinear optical characteristics of a new organic acentric material: L-Methionine-Succinic acid (2/1)

Science.gov (United States)

Nageshwari, M.; Kumari, C. Rathika Thaya; Vinitha, G.; Mohamed, M. Peer; Sudha, S.; Caroline, M. Lydia

2018-03-01

L-Methionine-Succinic acid (2/1) (LMSA), 2C5H11NO2S·C4H6O4, a novel nonlinear optical material which belongs to the class of organic category was grown-up for the first time by the technique of slow evaporation. Purity of LMSA was improved using repetitive recrystallization. LMSA was analyzed by single crystal and powder X-ray diffraction investigation to affirm the crystal structure and crystalline character. The single crystal XRD revealed that LMSA corresponds to the crystal system of triclinic with P1 as space group showing the asymmetric unit consists of a neutral succinic acid molecule and two methionine residues which are crystallographically independent existing in zwitterionic form. The functional groups existing in LMSA was accomplished using Fourier transform infrared spectroscopy. The optical transparency and the band gap energy were identified utilizing UV-Visible spectrum. The optical constants specifically reflectance and extinction coefficient clearly indicate the elevated transparency of LMSA. The thermal analyses affirmed its thermal stability. The luminescence behavior of LMSA has been analyzed by Photoluminescence (PL) spectral study. The mechanical, laser damage threshold and dielectric investigation of LMSA was done to suggest the material for practical applications. The second and third harmonic generation efficacy was confirmed by means of Kurtz-Perry and Z-scan procedure which attest its potentiality in the domain of nonlinear optics.
Proteomic Analysis of Stationary Phase in the Marine Bacterium "Candidatus Pelagibacter ubique"

Energy Technology Data Exchange (ETDEWEB)

Sowell, S. M.; Norbeck, A. D.; Lipton, M. S.; Nicora, C. D.; Callister, S. J.; Smith, R. D.; Barofsky, D. F.; Giovannoni, S. J.

2008-05-09

The α-proteobacterium ‘Candidatus Pelagibacter ubique’ str. HTCC1062, and most other members of the SAR11 clade, lack genes for assimilatory sulfate reduction, making them dependent on organosulfur compounds that occur naturally in seawater. To investigate how these cells adapt to sulfur limitation, batch cultures were grown in defined media containing either limiting or non-limiting amounts of dimethylsulfoniopropionate (DMSP) as the sole sulfur source. Protein and mRNA expression were measured during exponential growth, immediately prior to stationary phase, and in late stationary phase. Two distinct responses were observed: one as DMSP became exhausted, and another as cells acclimated to a sulfur-limited environment. The first response was characterized by increased transcription and translation of all Ca. P. ubique genes downstream of previously confirmed S-adenosyl methionine (SAM) riboswitches: bhmT, mmuM, and metY. Proteins encoded by these genes were up to 33 times more abundant as DMSP became limiting. Their predicted function is to shunt all available sulfur to methionine. The secondary response, observed during sulfur-depleted stationary phase, was a 6-10 fold increase in transcription of the heme c shuttle ccmC and two small genes of unknown function (SAR11_1163 and SAR11_1164). This bacterium's strategy for coping with sulfur stress appears to be intracellular redistribution to support methionine biosynthesis, rather than increasing organosulfur import. Many of the genes and SAM riboswitches involved in this response are located in a hypervariable genome region (HVR). One of these HVR genes, ordL, is located downstream of a conserved motif that evidence suggests is a novel riboswitch.
Molecular cloning, characterization and expression of the caffeic acid O-methyltransferase (COMT) ortholog from kenaf (Hibiscus cannabinus)

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We cloned the full-length of the gene putatively encoding caffeic acid O-methyltransferase (COMT) from kenaf (Hibiscus cannabinus L.) using degenerate primers and the RACE (rapid amplification of cDNA ends) method. Kenaf is an herbaceous and rapidly growing dicotyledonous plant with great potential ...
Nonnatural amino acid incorporation into the methionine 214 position of the metzincin Pseudomonas aeruginosa alkaline protease

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Honek John F

2005-10-01

Full Text Available Abstract Background The alkaline protease from Pseudomonas aeruginosa (AprA is a member of the metzincin superfamily of metalloendoproteases. A key feature of these proteases is a conserved methionine-containing 1,4-tight β turn at the base of the active site zinc binding region. Results To explore the invariant methionine position in this class of protease, incorporation of a nonnatural fluorinated methionine, L-difluoromethionine (DFM, into this site was accomplished. Although overproduction of the N-terminal catalytic fragment of AprA resulted in protein aggregates which could not be resolved, successful heterologous production of the entire AprA was accomplished in the presence and absence of the nonnatural amino acid. DFM incorporation was found to only slightly alter the enzyme kinetics of AprA. In addition, differential scanning calorimetry indicated no significant alteration in the thermal stability of the modified enzyme. Conclusion Although invariant in all metzincin proteases, the methionine 214 position in AprA can be successfully replaced by the nonnatural amino acid DFM resulting in little effect on protein structure and function. This study indicates that the increased size of the methyl group by the introduction of two fluorines is still sufficiently non-sterically demanding, and bodes well for the application of DFM to biophysical studies of protein structure and function in this class of protease.
Nonnatural amino acid incorporation into the methionine 214 position of the metzincin Pseudomonas aeruginosa alkaline protease

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Walasek, Paula; Honek, John F

2005-01-01

Background The alkaline protease from Pseudomonas aeruginosa (AprA) is a member of the metzincin superfamily of metalloendoproteases. A key feature of these proteases is a conserved methionine-containing 1,4-tight β turn at the base of the active site zinc binding region. Results To explore the invariant methionine position in this class of protease, incorporation of a nonnatural fluorinated methionine, L-difluoromethionine (DFM), into this site was accomplished. Although overproduction of the N-terminal catalytic fragment of AprA resulted in protein aggregates which could not be resolved, successful heterologous production of the entire AprA was accomplished in the presence and absence of the nonnatural amino acid. DFM incorporation was found to only slightly alter the enzyme kinetics of AprA. In addition, differential scanning calorimetry indicated no significant alteration in the thermal stability of the modified enzyme. Conclusion Although invariant in all metzincin proteases, the methionine 214 position in AprA can be successfully replaced by the nonnatural amino acid DFM resulting in little effect on protein structure and function. This study indicates that the increased size of the methyl group by the introduction of two fluorines is still sufficiently non-sterically demanding, and bodes well for the application of DFM to biophysical studies of protein structure and function in this class of protease. PMID:16221305
Formation of S-(carboxymethyl)-cysteine in rat liver mitochondrial proteins: effects of caloric and methionine restriction.

Science.gov (United States)

Naudí, Alba; Jové, Mariona; Cacabelos, Daniel; Ayala, Victoria; Cabre, Rosanna; Caro, Pilar; Gomez, José; Portero-Otín, Manuel; Barja, Gustavo; Pamplona, Reinald

2013-02-01

Maillard reaction contributes to the chemical modification and cross-linking of proteins. This process plays a significant role in the aging process and determination of animal longevity. Oxidative conditions promote the Maillard reaction. Mitochondria are the primary site of oxidants due to the reactive molecular species production. Mitochondrial proteome cysteine residues are targets of oxidative attack due to their specific chemistry and localization. Their chemical, non-enzymatic modification leads to dysfunctional proteins, which entail cellular senescence and organismal aging. Previous studies have consistently shown that caloric and methionine restrictions, nutritional interventions that increase longevity, decrease the rate of mitochondrial oxidant production and the physiological steady-state levels of markers of oxidative damage to macromolecules. In this scenario, we have detected S-(carboxymethyl)-cysteine (CMC) as a new irreversible chemical modification in mitochondrial proteins. CMC content in mitochondrial proteins significantly correlated with that of the lysine-derived analog N (ε)-(carboxymethyl)-lysine. The concentration of CMC is, however, one order of magnitude lower compared with CML likely due in part to the lower content of cysteine with respect to lysine of the mitochondrial proteome. CMC concentrations decreases in liver mitochondrial proteins of rats subjected to 8.5 and 25 % caloric restriction, as well as in 40 and 80 % methionine restriction. This is associated with a concomitant and significant increase in the protein content of sulfhydryl groups. Data presented here evidence that CMC, a marker of Cys-AGE formation, could be candidate as a biomarker of mitochondrial damage during aging.
Robotic synthesis of [carbon-11]methionine

International Nuclear Information System (INIS)

Korsakov, M.V.; Kisselev, M.Y.; Solovyov, D.; Horti, A.G.; Vasilev, A.; Nilsson, L.E.; Ulin, J.

1992-01-01

[ 11 C]Methionine was prepared in a fully automated robotic synthesis, using the SCANDITRONIX robotic system starting from [ 11 C]I and homocysteine thiolactone. The product was purified using solid phase extraction on anionic exchange cartridges. The decay corrected yield was 60% based on CH 3 I and 16 min synthesis time. The radiochemical purity was 98-99% and the chemical impurities were: homocysteine 0.05-0.07 mg/ml, homocystine 0.005 mg/ml, 'cold' methionine 0.03-0.05 mg/ml, and homocysteine thiolactone 0.0008-0.002 mg/ml. The total procedure takes 30 min from EOB. (author) 6 figs., 3 tabs
High-performance liquid chromatographic radioenzymatic assay for plasma catecyholamines

International Nuclear Information System (INIS)

Klaniecki, T.S.; Corder, C.N.; McDonald, R.H. Jr.; Feldman, J.A.

1977-01-01

A new assay method for plasma catecholamimes (CA) requiring only 50 μl has been developed, which uses high performance liquid chromatography (HPLC). The norepinephrine (NE), dopamine (D), and epinephrine (E) compounds found in plasma are radioactively o-methylated with S-[methyl- 3 H]-adenosyl-L-methionine ( 3 H-SAM) 3 H-SAM by the reaction of catechol-o-methyl transferase (COMT). The reaction is terminated and a standard mixture of nonradioactive o-methylated analogues of NE, D, and E is added to act as a carrier. Following separation by HPLC, the D,L-normetanephrine (NMN), 3-methoxy-4-hydroxyphenylethyl-amine or 3-methoxytyramine (3-MOT), and metanephrine (MN) radioactive peaks are collected which represent NE, D, and E, respectively. Then MNM and MN are oxidized to vanillin, and 3-MOT is acetylated. The products are subsequently separated by solvent extraction. This is necessary in order to avoid high radioactive blanks and to allow quantitation of the radioactivity by liquid scintillation spectrometry. The mean supine levels of NE, D, and E in normal subjects were respectively 182, 33, and 87 pg/ml of plasma. Similar assays on patients with pheochromocytoma revealed 797, 80, and 470 pg/ml
Dry-extrusion of Asian Carp to supplement natural methionine for organic poultry production

Science.gov (United States)

Methionine, a sulfur containing amino acid, is essential for healthy poultry production. Synthetic methionine is commonly used as a supplement in conventional poultry. However, for organic poultry in the United States, a natural, cost effective source of methionine that can replace synthetic methion...
Overexpressing both ATP sulfurylase and selenocysteine methyltransferase enhances selenium phytoremediation traits in Indian mustard

International Nuclear Information System (INIS)

LeDuc, Danika L.; AbdelSamie, Manal; Montes-Bayon, Maria; Wu, Carol P.; Reisinger, Sarah J.; Terry, Norman

2006-01-01

A major goal of our selenium (Se) phytoremediation research is to use genetic engineering to develop fast-growing plants with an increased ability to tolerate, accumulate, and volatilize Se. To this end we incorporated a gene (encoding selenocysteine methyltransferase, SMT) from the Se hyperaccumulator, Astragalus bisulcatus, into Indian mustard (LeDuc, D.L., Tarun, A.S., Montes-Bayon, M., Meija, J., Malit, M.F., Wu, C.P., AbdelSamie, M., Chiang, C.-Y., Tagmount, A., deSouza, M., Neuhierl, B., Boeck, A., Caruso, J., Terry, N., 2004. Overexpression of selenocysteine methyltransferase in Arabidopsis and Indian mustard increases selenium tolerance and accumulation Plant Physiol. 135, 377-383.). The resulting transgenic plants successfully enhanced Se phytoremediation in that the plants tolerated and accumulated Se from selenite significantly better than wild type. However, the advantage conferred by the SMT enzyme was much less when Se was supplied as selenate. In order to enhance the phytoremediation of selenate, we developed double transgenic plants that overexpressed the gene encoding ATP sulfurylase (APS) in addition to SMT, i.e., APS x SMT. The results showed that there was a substantial improvement in Se accumulation from selenate (4 to 9 times increase) in transgenic plants overexpressing both APS and SMT. - Simultaneous overexpression of APS and SMT genes in Indian mustard greatly increases ability to accumulate selenate

Intramolecular carbenoid ylide forming reactions of 2-diazo-3-keto-4-phthalimidocarboxylic esters derived from methionine and cysteine

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Marc Enßle

2012-03-01

Full Text Available Methionine, S-benzylcysteine and S-allylcysteine were converted into 2-diazo-3-oxo-4-phthalimidocarboxylic esters 8a–c in three steps. Upon rhodium-catalysed dediazoniation, two intramolecular carbenoid reactions competed, namely the formation of a cyclic sulfonium ylide and that of a six-ring carbonyl ylide. The S-methyl and S-benzyl ylides 12a and b could be isolated, while S-allyl ylide 12c underwent a [2,3]-sigmatropic rearrangement. The short-lived carbonyl ylides derived from methionine and S-benzylcysteine formed head-to-tail dimers by a [3 + 3]-cycloaddition and could be trapped with external dipolarophiles, while the S-allyl derivative 14c yielded the pentacyclic compound 17 by an intramolecular [3 + 2]-cycloaddition reaction.
Pharmacokinetics of [14C]methylglyoxal-bis-guanylhydrazone) in patients with leukemia.

Science.gov (United States)

Rosenblum, M G; Keating, M J; Yap, B S; Loo, T L

1981-05-01

Methylglyoxal-bis(guanylhydrazone) (MGBG; NSC 32946), a competitive inhibitor of S-adenosyl-L-methionine decarboxylase (EC 4.1.1.50), currently being reevaluated for its clinical antileukemic activity. MGBG labeled with 14C in the guanylhydrazone moiety was administered i.v. (150 microCi; specific activity, 1.9 microCi/mumol; 20 mg total) to six patients with leukemia. All patients in the study had normal renal and hepatic function. [14C]MGBG underwent no in vivo metabolism; it disappeared from the plasma with an average terminal t 1/2 of 4.1 hr. The 72-hr cumulative urinary excretion was only 14.5 +/- 2.2% (S.E.M.) of the total radioactive dose. The apparent volume of distribution was 661 ml/kg and the total clearance rate was 21.2 ml/kg/min. The low urinary excretion rate and the relatively rapid plasma clearance suggest that MGBG may be sequestered in the body. Therefore, if MGBG is administered by a frequent treatment schedule, the prolonged biological half-life in humans may significantly contribute to its clinical toxicity.
Effect of a Food Supplement Containing L-Methionine on Urinary Tract Infections in Pregnancy: A Prospective, Multicenter Observational Study.

Science.gov (United States)

Passaro, Mario; Mainini, Giampaolo; Ambrosio, Francesco; Sgambato, Raimondo; Balbi, Giancarlo

2017-06-01

Adjuvants or alternatives to antibiotics in urinary tract infections (UTIs) during pregnancy seem advisable because of possible fetal stress. The present study assessed the effectiveness of a food supplement containing L-methionine and Hibiscus sabdariffa L. and Boswellia serrata Roxb. extracts as a treatment for symptomatic UTIs in pregnancy. Pregnant patients with symptomatic cystitis were screened for UTIs in three different clinical centers. Those unwilling to take antibiotics were offered two alternative treatments: (A) a 1-week treatment with the food supplement or (B) a week in which they were advised to increase their fluid consumption to more than 1.5 L daily. After 1 week, group B patients who still had positive urine cultures (UCs) or had no UC performed took the food supplement for an additional week. UCs were performed on all patients at the first visit (w0) and on most of them at 7 days (w1). Patients who were still positive at w1 or had no UC performed at w1 had UC performed 14 days (w2) thereafter. Of 264 pregnant women enrolled, 216 joined group A, while 48 joined group B. At w1, 70.0% of group A patients and 43.2% of those in group B had negative UCs (p = 0.003). The reduction of bacterial load was 42.2% ± 8.0% and 4.5% ± 9.2%, respectively (p UTI in pregnancy.
Utility of “1”1C -methionine PET/CT in neuro-oncology

International Nuclear Information System (INIS)

Casas Parera, I.; Igirio Gamero, J.L.; Báez, A.; Tafur Canabal, J.G.; Báez, M.; Kuchkaryan, V.; B lumenkrantz, Y.; Bruno, G.

2013-01-01

Positron emission tomography (PET) with “1”1C-methionine (“1”1C-methionine PET/CT) is a new technique used to evaluate primary central nervous system (CNS) tumors. We describe our experience regarding the first 4 patients with glial tumors and “1”1C-methionine PET/CT. This is a descriptive, observational and prospective study of 4 patients between 38-50 years of age, with different gliomas (WHO classification). MRI and “1”1C-methionine PET/CT were performed in all cases. Case 1, gliomatosis cerebri grade II post-radiotherapy. Case 2, oligodendroglioma grade II diagnosed and treated with radiotherapy in 1993. Case 3, glioblastoma grade IV post-radiotherapy + temozolomide. Case 4, anaplastic oligoastrocytoma grade III post-radiotherapy + temozolomide. The pattern of “1”1C-methionine uptake compared with MRI showed tumor progression in cases 1, 3 and 4, and in case 2 showed uptake although the final diagnosis was pseudoprogression. Unlike “1”8fluordeoxiglucose PET/TC, “1”1C-methionine uptake in normal brain tissue and pseudoprogression is low, and gliomas are displayed as metabolically active areas. The “1”1C-methionine PET/CT provided valuable information on the tumoral behavior and extension, although in one case presented did not differentiate tumor progression from pseudoprogression. “1”1C-methionine PET/CT could be a useful tool in the study and follow-up to patients with gliomas. (authors) [es
Why Nature Uses Radical SAM Enzymes so Widely: Electron Nuclear Double Resonance Studies of Lysine 2,3-Aminomutase Show the 5′-dAdo• “Free Radical” Is Never Free

Science.gov (United States)

Horitani, Masaki; Byer, Amanda S.; Shisler, Krista A.; Chandra, Tilak; Broderick, Joan B.; Hoffman, Brian M.

2015-01-01

Lysine 2,3-aminomutase (LAM) is a radical S-adenosyl-L-methionine (SAM) enzyme and, like other members of this superfamily, LAM utilizes radical-generating machinery comprising SAM anchored to the unique Fe of a [4Fe-4S] cluster via a classical five-membered N,O chelate ring. Catalysis is initiated by reductive cleavage of the SAM S–C5′ bond, which creates the highly reactive 5′-deoxyadenosyl radical (5′-dAdo•), the same radical generated by homolytic Co–C bond cleavage in B12 radical enzymes. The SAM surrogate S-3′,4′-anhydroadenosyl-L-methionine (anSAM) can replace SAM as a cofactor in the isomerization of L-α-lysine to L-β-lysine by LAM, via the stable allylic anhydroadenosyl radical (anAdo•). Here electron nuclear double resonance (ENDOR) spectroscopy of the anAdo• radical in the presence of 13C, 2H, and 15N-labeled lysine completes the picture of how the active site of LAM from Clostridium subterminale SB4 “tames” the 5′-dAdo• radical, preventing it from carrying out harmful side reactions: this “free radical” in LAM is never free. The low steric demands of the radical-generating [4Fe-4S]/SAM construct allow the substrate target to bind adjacent to the S–C5′ bond, thereby enabling the 5′-dAdo• radical created by cleavage of this bond to react with its partners by undergoing small motions, ~0.6 Å toward the target and ~1.5 Å overall, that are controlled by tight van der Waals contact with its partners. We suggest that the accessibility to substrate and ready control of the reactive C5′ radical, with “van der Waals control” of small motions throughout the catalytic cycle, is common within the radical SAM enzyme superfamily and is a major reason why these enzymes are the preferred means of initiating radical reactions in nature. PMID:25923449
Digestible methionine + cystine requirement for Nile tilapia from 550 to 700 g

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Mariana Michelato

2013-01-01

Full Text Available This trial was conducted to determine the dietary digestible methionine + cystine requirement of Nile tilapia (550 to 700 g based on the ideal protein concept. Six hundred fish were distributed in a completely randomized design with five treatments and four replicates, with 30 fish per experimental unit. The fish were fed diets containing approximately 262 g of digestible protein/kg, 3,040 kcal of digestible energy/kg and 7.90, 9.40, 10.90, 12.40 or 13.90 g of methionine + cystine/kg. The fish were hand-fed three times a day until apparent satiation for 30 days. No effects of dietary methionine + cystine on feed conversion ratio, daily protein deposition, whole body moisture, fillet moisture, crude protein, ether extract and ash, plasmatic HDL and LDL cholesterol were observed. Dietary methionine resulted in a linear increase in whole body protein and linear reduction in lipid deposition rate, hepatosomatic index, whole body ether extract and ash, plasmatic total cholesterol, plasmatic total lipids and plasmatic triglycerides. According to the Linear Response Plateau, the daily weight gain and fillet yield increased up to a level of 9.00 and 9.90 g methionine + cystine/kg of diet, respectively. The digestible methionine + cystine requirement of Nile tilapia is 9.00 g/kg for weight gain and 9.90 g/kg for fillet yield, corresponding to methionine + cystine:lysine ratios of 0.60 and 0.66, respectively.
Different Levels of Digestible Methionine on Performance of Broiler Starter

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WL Bryden

2010-01-01

Full Text Available Dietary protein and amino acid supply is the most expensive component of poultry diets. Therefore several efforts made by the industry to minimize the cost of the protein portion of the diet. Accordingly, there has been a recent move to use digestible amino acid values in the formulation of poultry diets. The efficiency of protein utilization depends to a large extent on the amino acid composition of the diet. The study was conducted to determine the digestible methionine requirement of broilers during the starter periods. One hundred and seventy five (175 chicks were allocated to 5 treatments with five replicates of seven chicks per replicate in a completely randomized design. Chicks were fed experimental diets from one day old to 21 days of age. Dietary treatments included 5 titrated levels each of digestible methionine (3.0, 4.5, 6.0, 7.5, and 9.0 g/kg diet added to a basal diet. The allowance of digestible methionine, rather than digestible sulphur amino acids was used in formulating the diets. Supplemental synthetic DL-Methionine which were considered to be 100% digestible were added to diets to obtain the concentration of the digestible amino acid. Each week until the conclusion of the trial, birds were individually weighed, feed intake per pen was measured, and feed conversion ratio (FCR was computed. This study suggested that the digestible methionine requirement for broiler starter is 4.7 g/kg for optimal body weight gain and 4.6 g/kg for optimal feed conversion ratio. (Animal Production 12(1: 6-11 (2010Key Words: amino acid, broiler, digestible, methionine, starter
Mutations at the S1 sites of methionine aminopeptidases from Escherichia coli and Homo sapiens reveal the residues critical for substrate specificity.

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Li, Jing-Ya; Cui, Yong-Mei; Chen, Ling-Ling; Gu, Min; Li, Jia; Nan, Fa-Jun; Ye, Qi-Zhuang

2004-05-14

Methionine aminopeptidase (MetAP) catalyzes the removal of methionine from newly synthesized polypeptides. MetAP carries out this cleavage with high precision, and Met is the only natural amino acid residue at the N terminus that is accepted, although type I and type II MetAPs use two different sets of residues to form the hydrophobic S1 site. Characteristics of the S1 binding pocket in type I MetAP were investigated by systematic mutation of each of the seven S1 residues in Escherichia coli MetAP type I (EcMetAP1) and human MetAP type I (HsMetAP1). We found that Tyr-65 and Trp-221 in EcMetAP1, as well as the corresponding residues Phe-197 and Trp-352 in HsMetAP1, were essential for the hydrolysis of a thiopeptolide substrate, Met-S-Gly-Phe. Mutation of Phe-191 to Ala in HsMetAP1 caused inactivity in contrast to the full activity of EcMetAP1(Y62A), which may suggest a subtle difference between the two type I enzymes. The more striking finding is that mutation of Cys-70 in EcMetAP1 or Cys-202 in HsMetAP1 opens up the S1 pocket. The thiopeptolides Leu-S-Gly-Phe and Phe-S-Gly-Phe, with previously unacceptable Leu or Phe as the N-terminal residue, became efficient substrates of EcMetAP1(C70A) and HsMetAP1(C202A). The relaxed specificity shown in these S1 site mutants for the N-terminal residues was confirmed by hydrolysis of peptide substrates and inhibition by reaction products. The structural features at the enzyme active site will be useful information for designing specific MetAP inhibitors for therapeutic applications.
New multilayer coating using quaternary ammonium chitosan and κ-carrageenan in capillary electrophoresis: application in fast analysis of betaine and methionine.

Science.gov (United States)

Vitali, Luciano; Della Betta, Fabiana; Costa, Ana Carolina O; Vaz, Fernando Antonio Simas; Oliveira, Marcone Augusto Leal; Vistuba, Jacqueline Pereira; Fávere, Valfredo T; Micke, Gustavo A

2014-06-01

The aim of this study was to develop a new multilayer coating with crosslinked quaternary ammonium chitosan (hydroxypropyltrimethyl ammonium chloride chitosan; HACC) and κ-carrageenan for use in capillary electrophoresis. A new semi-permanent multilayer coating was formed using the procedure developed and the method does not require the presence of polymers in the background electrolyte (BGE). The new capillary multilayer coating showed a cathodic electroosmotic flow (EOF) of around 30×10(-9) m(2) V(-1) s(-1) which is pH-independent in the range of pH 2 to 10. The enhanced EOF at low pH obtained contributed significantly to the development of a fast method of separation. The multilayer coating was then applied in the development of a fast separation method to determine betaine and methionine in pharmaceutical formulations by capillary zone electrophoresis (CZE). The BGE used to determine the betaine and methionine concentrations was composed of 10 mmol L(-1) tris(hydroxymethyl) aminomethane, 40 mmol L(-1) phosphoric acid and 10% (v/v) ethanol, at pH 2.1. A fused-silica capillary of 32 cm (50 µm ID×375 µm OD) was used in the experiments and samples and standards were analyzed employing the short-end injection procedure (8.5 cm effective length). The instrumental analysis time of the optimized method was 1.53 min (approx. 39 runs per hour). The validation of the proposed method for the determination of betaine and methionine showed good linearity (R(2)>0.999), adequate limit of detection (LOD <8 mg L(-1)) for the concentration in the samples and inter-day precision values lower than 3.5% (peak area and time migration). The results for the quantification of the amino acids in the samples determined by the CZE-UV method developed were statistically equal to those obtained with the comparative LC-MS/MS method according to the paired t-test with a confidence level of 95%. Copyright © 2014 Elsevier B.V. All rights reserved.
Effects of Glycine, Water, Ammonia, and Ammonium Bicarbonate on the Oligomerization of Methionine

Science.gov (United States)

Huang, Rui; Furukawa, Yoshihiro; Otake, Tsubasa; Kakegawa, Takeshi

2017-06-01

The abiotic oligomerization of amino acids may have created primordial, protein-like biological catalysts on the early Earth. Previous studies have proposed and evaluated the potential of diagenesis for the amino acid oligomerization, simulating the formation of peptides that include glycine, alanine, and valine, separately. However, whether such conditions can promote the formation of peptides composed of multiple amino acids remains unclear. Furthermore, the chemistry of pore water in sediments should affect the oligomerization and degradation of amino acids and oligomers, but these effects have not been studied extensively. In this study, we investigated the effects of water, ammonia, ammonium bicarbonate, pH, and glycine on the oligomerization and degradation of methionine under high pressure (150 MPa) and high temperature conditions (175 °C) for 96 h. Methionine is more difficult to oligomerize than glycine and methionine dimer was formed in the incubation of dry powder of methionine. Methionine oligomers as long as trimers, as well as methionylglycine and glycylmethionine, were formed under every condition with these additional compounds. Among the compounds tested, the oligomerization reaction rate was accelerated by the presence of water and by an increase in pH. Ammonia also increased the oligomerization rate but consumed methionine by side reactions and resulted in the rapid degradation of methionine and its peptides. Similarly, glycine accelerated the oligomerization rate of methionine and the degradation of methionine, producing water, ammonia, and bicarbonate through its decomposition. With Gly, heterogeneous dimers (methionylglycine and glycylmethionine) were formed in greater amounts than with other additional compounds although smaller amount of these heterogeneous dimers were formed with other additional compounds. These results suggest that accelerated reaction rates induced by water and co-existing reactive compounds promote the oligomerization
Preparation, crystallization and preliminary X-ray analysis of the methionine synthase (MetE) from Streptococcus mutans

International Nuclear Information System (INIS)

Fu, Tian-Min; Zhang, Xiao-Yan; Li, Lan-Fen; Liang, Yu-He; Su, Xiao-Dong

2006-01-01

Methionine synthase (MetE) from S. mutans was expressed, purified and crystallized. Diffraction data have been collected to 2.2 Å resolution. The Streptococcus mutans metE gene encodes methionine synthase (MetE), which catalyzes the direct transfer of a methyl group from methyltetrahydrofolate to homocysteine in the last step of methionine synthesis. metE was cloned into pET28a and the gene product was expressed at high levels in the Escherichia coli strain BL21 (DE3). MetE was purified to homogeneity using Ni 2+ -chelating chromatography followed by size-exclusion chromatography. Crystals of the protein were obtained by the hanging-drop vapour-diffusion method and diffracted to 2.2 Å resolution. The crystal belongs to space group P2 1 , with unit-cell parameters a = 52.85, b = 99.48, c = 77.88 Å, β = 94.55°
Egg quality of quails fed low methionine diet supplemented with betaine

Science.gov (United States)

Ratriyanto, A.; Indreswari, R.; Dewanti, R.; Wahyuningsih, S.

2018-03-01

This experiment investigated the effect of betaine supplementation to low methionine diet on egg quality of quails. A total of 340 laying quails (Coturnix coturnix japonica) was divided into 4 dietary treatments with 5 replicates of 17 quails each. The experiment was assigned in a completely randomized design. The four dietary treatments were the low methionine diet (0.3% methionine) without betaine supplementation and the low methionine diet supplemented with 0.07, 0.14, and 0.21% betaine. The experimental diets were applied for 8 weeks and the egg quality traits were measured at the age of 16 and 20 weeks. The data were subjected to analysis of variance, and when the treatment indicated significant effect, it was continued to orthogonal polynomial test to determine the optimum level of betaine. Increasing dietary levels of betaine increased the fat content of the egg with the linear regression of y = 11.0949 + 4.1914x (R2 = 0.18). However, supplementation of betaine did not affect protein content, yolk, albumen, and eggshell percentage. It can be concluded that betaine supplementation up to 0.21% to low methionine diet only had little effect in improving the quality traits of quail eggs.
Membrane topology of Golgi-localized probable S-adenosylmethionine-dependent methyltransferase in tobacco (Nicotiana tabacum) BY-2 cells.

Science.gov (United States)

Liu, Jianping; Hayashi, Kyoko; Matsuoka, Ken

2015-01-01

S-adenosylmethionine (SAM)-dependent methyltransferases (MTases) transfer methyl groups to substrates. In this study, a novel putative tobacco SAM-MTase termed Golgi-localized methyl transferase 1 (GLMT1) has been characterized. GLMT1 is comprised of 611 amino acids with short N-terminal region, putative transmembrane region, and C-terminal SAM-MTase domain. Expression of monomeric red fluorescence protein (mRFP)-tagged protein in tobacco BY-2 cell indicated that GLMT1 is a Golgi-localized protein. Analysis of the membrane topology by protease digestion suggested that both C-terminal catalytic region and N-terminal region seem to be located to the cytosolic side of the Golgi apparatus. Therefore, GLMT1 might have a different function than the previously studied SAM-MTases in plants.
Increasing levels of dietary crystalline methionine affect plasma methionine profiles, ammonia excretion, and the expression of genes related to the hepatic intermediary metabolism in rainbow trout (Oncorhynchus mykiss)

DEFF Research Database (Denmark)

Rolland, Marine; Skov, Peter Vilhelm; Larsen, Bodil Katrine

2016-01-01

Strictly carnivorous fish with high requirements for dietary protein, such as rainbow trout (Oncorhynchus mykiss) are interesting models for studying the role of amino acids as key regulators of intermediary metabolism. Methionine is an essential amino acid for rainbow trout, and works as a signa......Strictly carnivorous fish with high requirements for dietary protein, such as rainbow trout (Oncorhynchus mykiss) are interesting models for studying the role of amino acids as key regulators of intermediary metabolism. Methionine is an essential amino acid for rainbow trout, and works...... as a signalling factor in different metabolic pathways. The study investigated the effect of increasing dietary methionine intake on the intermediary metabolism in the liver of juvenile rainbow trout. For this purpose, five diets were formulated with increasing methionine levels from 0.60 to 1.29% dry matter....... The diets were fed in excess for six weeks before three sampling campaigns carried out successively to elucidate (i) the hepatic expression of selected genes involved in lipid, glucose and amino acid metabolism; (ii) the postprandial ammonia excretion; and (iii) the postprandial plasma methionine...
Diphthamide biosynthesis requires an organic radical generated by an iron-sulphur enzyme

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yang; Zhu, Xuling; Torelli, Andrew T; Lee, Michael; Dzikovski, Boris; Koralewski, Rachel M; Wang, Eileen; Freed, Jack; Krebs, Carsten; Ealick, Steve E; Lin, Hening [Cornell; (Penn)

2010-08-30

Archaeal and eukaryotic translation elongation factor 2 contain a unique post-translationally modified histidine residue called diphthamide, which is the target of diphtheria toxin. The biosynthesis of diphthamide was proposed to involve three steps, with the first being the formation of a C-C bond between the histidine residue and the 3-amino-3-carboxypropyl group of S-adenosyl-l-methionine (SAM). However, further details of the biosynthesis remain unknown. Here we present structural and biochemical evidence showing that the first step of diphthamide biosynthesis in the archaeon Pyrococcus horikoshii uses a novel iron-sulphur-cluster enzyme, Dph2. Dph2 is a homodimer and each of its monomers can bind a [4Fe-4S] cluster. Biochemical data suggest that unlike the enzymes in the radical SAM superfamily, Dph2 does not form the canonical 5'-deoxyadenosyl radical. Instead, it breaks the C_γ,Met-S bond of SAM and generates a 3-amino-3-carboxypropyl radical. Our results suggest that P. horikoshii Dph2 represents a previously unknown, SAM-dependent, [4Fe-4S]-containing enzyme that catalyses unprecedented chemistry.
Adenosine kinase deficiency disrupts the methionine cycle and causes hypermethioninemia, encephalopathy, and abnormal liver function.

Science.gov (United States)

Bjursell, Magnus K; Blom, Henk J; Cayuela, Jordi Asin; Engvall, Martin L; Lesko, Nicole; Balasubramaniam, Shanti; Brandberg, Göran; Halldin, Maria; Falkenberg, Maria; Jakobs, Cornelis; Smith, Desiree; Struys, Eduard; von Döbeln, Ulrika; Gustafsson, Claes M; Lundeberg, Joakim; Wedell, Anna

2011-10-07

Four inborn errors of metabolism (IEMs) are known to cause hypermethioninemia by directly interfering with the methionine cycle. Hypermethioninemia is occasionally discovered incidentally, but it is often disregarded as an unspecific finding, particularly if liver disease is involved. In many individuals the hypermethioninemia resolves without further deterioration, but it can also represent an early sign of a severe, progressive neurodevelopmental disorder. Further investigation of unclear hypermethioninemia is therefore important. We studied two siblings affected by severe developmental delay and liver dysfunction. Biochemical analysis revealed increased plasma levels of methionine, S-adenosylmethionine (AdoMet), and S-adenosylhomocysteine (AdoHcy) but normal or mildly elevated homocysteine (Hcy) levels, indicating a block in the methionine cycle. We excluded S-adenosylhomocysteine hydrolase (SAHH) deficiency, which causes a similar biochemical phenotype, by using genetic and biochemical techniques and hypothesized that there was a functional block in the SAHH enzyme as a result of a recessive mutation in a different gene. Using exome sequencing, we identified a homozygous c.902C>A (p.Ala301Glu) missense mutation in the adenosine kinase gene (ADK), the function of which fits perfectly with this hypothesis. Increased urinary adenosine excretion confirmed ADK deficiency in the siblings. Four additional individuals from two unrelated families with a similar presentation were identified and shown to have a homozygous c.653A>C (p.Asp218Ala) and c.38G>A (p.Gly13Glu) mutation, respectively, in the same gene. All three missense mutations were deleterious, as shown by activity measurements on recombinant enzymes. ADK deficiency is a previously undescribed, severe IEM shedding light on a functional link between the methionine cycle and adenosine metabolism. Copyright © 2011 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.
Brain protein synthesis in normal and demented patients. A study by P.E.T. with 11C-L methionine

International Nuclear Information System (INIS)

Bustany, P.; Soussaline, F.; Comar, D.; Henry, J.F.

1982-09-01

A compartmental model representing protein synthesis in the brain was validated experimentally in 9 baboons. After sequential injections of 11 C, 3 H and 14 C methionines on the same animal, followed by P.E.T. recording of the γ activity in a chosen brain section with time, the distribution of methionine injected into the different compartments of the model after a bolus was measured by crushing and precipitation with T.C.A. The agreement between direct in vitro findings and computed results is excellent. This method of studying brain protein synthesis in vivo was applied to 28 Alzheimer dementia cases and 20 normal subjects of the same age. The correlation between the results of clinical and psychometric tests and the brain protein synthesis activity confirms an anomaly in this biochemical synthesis process during the illness. A 65% fall in activity may be found in the frontal lobes of certain patients
Development and validation of a hydrophilic interaction chromatography-mass spectrometry assay for taurine and methionine in matrices rich in carbohydrates.

Science.gov (United States)

de Person, Marine; Hazotte, Aurélie; Elfakir, Claire; Lafosse, Michel

2005-07-22

A new procedure based on hydrophilic interaction chromatography coupled to tandem mass spectrometry (ionisation process by pneumatically assisted electrospray in negative ion mode), is developed and validated for the simultaneous determination of underivatised taurine and methionine in beverages rich in carbohydrates such as energy drinks. No initial clean-up procedure and no sample derivatisation are required. Satisfactory analysis was obtained on an Astec apHera NH2 (150 mm x 4.6 mm; 5 microm) column with methanol-water (60/40) as mobile phase. The method was validated in terms of specificity, detection limits, linearity, accuracy, precision and stability, using threonine as internal standard. The potential effects of matrix and endogenous amino acid content were also examined. The limits of detection in the beverage varied from 20 microg L(-1) for taurine to 50 micro L(-1) for methionine.
Ontogeny of methionine utilization and splanchnic uptake in critically ill children

Science.gov (United States)

To determine the rates of methionine splanchnic uptake and utilization in critically ill pediatric patients, we used two kinetic models: the plasma methionine enrichment,and the "intracellular" homocysteine enrichment. Twenty-four patients, eight infants, eight children, and eight adolescents, were ...
Importance of methionine biosynthesis for Arabidopsis seed germination and seedling growth

NARCIS (Netherlands)

Gallardo, K.; Job, C.; Groot, S.P.C.; Puype, M.; Demol, H.; VandeKerckhove, J.; Job, D.

2002-01-01

Proteomics of Arabidopsis seeds revealed the differential accumulation during germination of two housekeeping enzymes. The first corresponded to methionine synthase that catalyses the last step in the plant methionine biosynthetic pathway. This protein was present at low level in dry mature seeds,

DZNep, inhibitor of S-adenosylhomocysteine hydrolase, down-regulates expression of SETDB1 H3K9me3 HMTase in human lung cancer cells.

Science.gov (United States)

Lee, Ju-Kyung; Kim, Keun-Cheol

2013-09-06

3-Deazaneplanocin A (DZNep), an epigenetic anticancer drug, leads to the indirect suppression of S-adenosyl methionine-dependent cellular methylations by inhibiting S-adenosyl homocystein (AdoHcy) hydrolase. Although it is well known that DZNep targets the degradation of EZH2 protein, H3K27me3 HMTase, there are still uncertainties about the regulation of other types of HMTases during cell death. In this study, we describe that SETDB1 gene expression was regulated by DZNep treatment in human lung cancer cells. We confirm that DZNep induced growth inhibition and increased the dead cell population of lung cancer cells. DZNep treatment affected histone methylations, including H3K27me3 and H3K9me3, but not H3K4me3. Reduced levels of H3K27me3 and H3K9me3 were related with the decreased EZH2 and SETDB1 proteins. Real time PCR analysis showed that SETDB1 gene expression was decreased by DZNep treatment, but no effect was observed for EZH2 gene expression. We cloned the promoter region of SETDB1 and SUV39H1 genes, and performed luciferase assays. The promoter activity of SETDB1 gene was down regulated by DZNep treatment, whereas no effect on SUV39H1 promoter activity was observed. In conclusion, we suggest that DZNep regulates not only on H3K27me3 HMTase EZH2, but also H3K9 HMTase SETDB1 gene expression at the transcription level, implicating that the mechanism of action of DZNep targets multiple HMTases during the death of lung cancer cells. Copyright © 2013 Elsevier Inc. All rights reserved.
Preparation, crystallization and preliminary X-ray analysis of the methionine synthase (MetE) from Streptococcus mutans

Energy Technology Data Exchange (ETDEWEB)

Fu, Tian-Min; Zhang, Xiao-Yan; Li, Lan-Fen; Liang, Yu-He, E-mail: liangyh@pku.edu.cn; Su, Xiao-Dong [National Laboratory of Protein Engineering and Plant Genetic Engineering, Peking University, Beijing 100871 (China); Department of Biochemistry and Molecular Biology, College of Life Sciences, Peking University, Beijing 100871 (China)

2006-10-01

Methionine synthase (MetE) from S. mutans was expressed, purified and crystallized. Diffraction data have been collected to 2.2 Å resolution. The Streptococcus mutans metE gene encodes methionine synthase (MetE), which catalyzes the direct transfer of a methyl group from methyltetrahydrofolate to homocysteine in the last step of methionine synthesis. metE was cloned into pET28a and the gene product was expressed at high levels in the Escherichia coli strain BL21 (DE3). MetE was purified to homogeneity using Ni{sup 2+}-chelating chromatography followed by size-exclusion chromatography. Crystals of the protein were obtained by the hanging-drop vapour-diffusion method and diffracted to 2.2 Å resolution. The crystal belongs to space group P2{sub 1}, with unit-cell parameters a = 52.85, b = 99.48, c = 77.88 Å, β = 94.55°.
The Metabolic Burden of Methyl Donor Deficiency with Focus on the Betaine Homocysteine Methyltransferase Pathway

Directory of Open Access Journals (Sweden)

Rima Obeid

2013-09-01

Full Text Available Methyl groups are important for numerous cellular functions such as DNA methylation, phosphatidylcholine synthesis, and protein synthesis. The methyl group can directly be delivered by dietary methyl donors, including methionine, folate, betaine, and choline. The liver and the muscles appear to be the major organs for methyl group metabolism. Choline can be synthesized from phosphatidylcholine via the cytidine-diphosphate (CDP pathway. Low dietary choline loweres methionine formation and causes a marked increase in S-adenosylmethionine utilization in the liver. The link between choline, betaine, and energy metabolism in humans indicates novel functions for these nutrients. This function appears to goes beyond the role of the nutrients in gene methylation and epigenetic control. Studies that simulated methyl-deficient diets reported disturbances in energy metabolism and protein synthesis in the liver, fatty liver, or muscle disorders. Changes in plasma concentrations of total homocysteine (tHcy reflect one aspect of the metabolic consequences of methyl group deficiency or nutrient supplementations. Folic acid supplementation spares betaine as a methyl donor. Betaine is a significant determinant of plasma tHcy, particularly in case of folate deficiency, methionine load, or alcohol consumption. Betaine supplementation has a lowering effect on post-methionine load tHcy. Hypomethylation and tHcy elevation can be attenuated when choline or betaine is available.
Polyamine metabolism influences antioxidant defense mechanism in foxtail millet (Setaria italica L.) cultivars with different salinity tolerance.

Science.gov (United States)

Sudhakar, Chinta; Veeranagamallaiah, Gounipalli; Nareshkumar, Ambekar; Sudhakarbabu, Owku; Sivakumar, M; Pandurangaiah, Merum; Kiranmai, K; Lokesh, U

2015-01-01

Polyamines can regulate the expression of antioxidant enzymes and impart plants tolerance to abiotic stresses. A comparative analysis of polyamines, their biosynthetic enzymes at kinetic and at transcriptional level, and their role in regulating the induction of antioxidant defense enzymes under salt stress condition in two foxtail millet (Setaria italica L.) cultivars, namely Prasad, a salt-tolerant, and Lepakshi, a salt-sensitive cultivar was conducted. Salt stress resulted in elevation of free polyamines due to increase in the activity of spermidine synthase and S-adenosyl methionine decarboxylase enzymes in cultivar Prasad compared to cultivar Lepakshi under different levels of NaCl stress. These enzyme activities were further confirmed at the transcript level via qRT-PCR analysis. The cultivar Prasad showed a greater decrease in diamine oxidase and polyamine oxidase activity, which results in the accumulation of polyamine pools over cultivar Lepakshi. Generation of free radicals, such as O 2 (·-) and H2O2, was also analyzed quantitatively. A significant increase in O 2 (·-) and H2O2 in the cultivar Lepakshi compared with cultivar Prasad was recorded in overall pool sizes. Further, histochemical staining showed lesser accumulation of O 2 (·-) and of H2O2 in the leaves of cultivar Prasad than cultivar Lepakshi. Our results also suggest the ability of polyamine oxidation in regulating the induction of antioxidative defense enzymes, which involve in the elimination of toxic levels of O 2 (·-) and H2O2, such as Mn-superoxide dismutase, catalase and ascorbate peroxidase. The contribution of polyamines in modulating antioxidative defense mechanism in NaCl stress tolerance is discussed.
Trafficking of α-L-fucosidase in lymphoid cells

International Nuclear Information System (INIS)

DiCioccio, R.A.; Brown, K.S.

1987-01-01

The quantity of α-L-fucosidase in human serum is determined by heredity. The mechanism controlling levels of the enzyme in serum is unknown. To investigate this, lymphoid cell lines derived from individuals with either low, intermediate or high α-L-fucosidase in serum were established. Steady state levels of extracellular α-L-fucosidase protein and activity overlapped among the cell lines. Thus, in vivo serum phenotypes of α-L-fucosidase are not adequately expressed in this system. α-L-Fucosidase was also metabolically labelled with 35 S-methionine, immunoprecipitated, and examined by SDS-PAGE. Cells pulse-labelled from 0.25-2 h had a major intracellular form of enzyme (Mr = 58,000). Cells pulsed for 1.5 h and chased for 21 h with unlabeled methionine had an intracellular form of Mr = 60,000 and an extracellular form of Mr = 62,000. Cells treated with chloroquine had only the 58,000-form both intra- and extra-cellularly. Moreover, chloroquine did not effect the quantitative distribution of α-L-fucosidase between cells and medium. In fibroblasts, chloroquine enhanced the secretion of newly made lysosomal enzymes and blocked the processing of intercellular enzyme forms from a higher to a lower molecular mass. Thus, there are trafficking differences between α-L-fucosidase in lymphoid cells and lysosomal enzymes in fibroblasts. This suggests that alternative targeting mechanisms for lysosomal enzymes exist in these cells
Structure and possible mechanism of the CcbJ methyltransferase from Streptomyces caelestis

Czech Academy of Sciences Publication Activity Database

Bauer, J.; Ondrovičová, G.; Najmanová, Lucie; Pevala, V.; Kameník, Zdeněk; Koštan, J.; Janata, Jiří; Kutejová, Eva

2014-01-01

Roč. 70, APR 2014 (2014), s. 943-957 ISSN 0907-4449 R&D Projects: GA MŠk(CZ) EE2.3.30.0003; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61388971 Keywords : CATECHOL-O-METHYLTRANSFERASE * SN2-LIKE TRANSITION-STATE * CRYSTAL-STRUCTURES Subject RIV: CE - Biochemistry Impact factor: 7.232, year: 2013
Drosophila arginine methyltransferase 1 (DART1) is an ecdysone receptor co-repressor

International Nuclear Information System (INIS)

Kimura, Shuhei; Sawatsubashi, Shun; Ito, Saya; Kouzmenko, Alexander; Suzuki, Eriko; Zhao, Yue; Yamagata, Kaoru; Tanabe, Masahiko; Ueda, Takashi; Fujiyama, Sari; Murata, Takuya; Matsukawa, Hiroyuki; Takeyama, Ken-ichi; Yaegashi, Nobuo

2008-01-01

Histone arginine methylation is an epigenetic marker that regulates gene expression by defining the chromatin state. Arginine methyltransferases, therefore, serve as transcriptional co-regulators. However, unlike other transcriptional co-regulators, the physiological roles of arginine methyltransferases are poorly understood. Drosophila arginine methyltransferase 1 (DART1), the mammalian PRMT1 homologue, methylates the arginine residue of histone H4 (H4R3me2). Disruption of DART1 in Drosophila by imprecise P-element excision resulted in low viability during metamorphosis in the pupal stages. In the pupal stage, an ecdysone hormone signal is critical for developmental progression. DART1 interacted with the nuclear ecdysone receptor (EcR) in a ligand-dependent manner, and co-repressed EcR in intact flies. These findings suggest that DART1, a histone arginine methyltransferase, is a co-repressor of EcR that is indispensable for normal pupal development in the intact fly
Stress-induced gene expression and behavior are controlled by DNA methylation and methyl donor availability in the dentate gyrus

Science.gov (United States)

Saunderson, Emily A.; Spiers, Helen; Gutierrez-Mecinas, Maria; Trollope, Alexandra F.; Shaikh, Abeera; Mill, Jonathan; Reul, Johannes M. H. M.

2016-01-01

Stressful events evoke long-term changes in behavioral responses; however, the underlying mechanisms in the brain are not well understood. Previous work has shown that epigenetic changes and immediate-early gene (IEG) induction in stress-activated dentate gyrus (DG) granule neurons play a crucial role in these behavioral responses. Here, we show that an acute stressful challenge [i.e., forced swimming (FS)] results in DNA demethylation at specific CpG (5′-cytosine–phosphate–guanine-3′) sites close to the c-Fos (FBJ murine osteosarcoma viral oncogene homolog) transcriptional start site and within the gene promoter region of Egr-1 (early growth response protein 1) specifically in the DG. Administration of the (endogenous) methyl donor S-adenosyl methionine (SAM) did not affect CpG methylation and IEG gene expression at baseline. However, administration of SAM before the FS challenge resulted in an enhanced CpG methylation at the IEG loci and suppression of IEG induction specifically in the DG and an impaired behavioral immobility response 24 h later. The stressor also specifically increased the expression of the de novo DNA methyltransferase Dnmt3a [DNA (cytosine-5-)-methyltransferase 3 alpha] in this hippocampus region. Moreover, stress resulted in an increased association of Dnmt3a enzyme with the affected CpG loci within the IEG genes. No effects of SAM were observed on stress-evoked histone modifications, including H3S10p-K14ac (histone H3, phosphorylated serine 10 and acetylated lysine-14), H3K4me3 (histone H3, trimethylated lysine-4), H3K9me3 (histone H3, trimethylated lysine-9), and H3K27me3 (histone H3, trimethylated lysine-27). We conclude that the DNA methylation status of IEGs plays a crucial role in FS-induced IEG induction in DG granule neurons and associated behavioral responses. In addition, the concentration of available methyl donor, possibly in conjunction with Dnmt3a, is critical for the responsiveness of dentate neurons to environmental
Catechol-O-methyltransferase val158met polymorphism predicts placebo effect in irritable bowel syndrome.

Directory of Open Access Journals (Sweden)

Kathryn T Hall

Full Text Available Identifying patients who are potential placebo responders has major implications for clinical practice and trial design. Catechol-O-methyltransferase (COMT, an important enzyme in dopamine catabolism plays a key role in processes associated with the placebo effect such as reward, pain, memory and learning. We hypothesized that the COMT functional val158met polymorphism, was a predictor of placebo effects and tested our hypothesis in a subset of 104 patients from a previously reported randomized controlled trial in irritable bowel syndrome (IBS. The three treatment arms from this study were: no-treatment ("waitlist", placebo treatment alone ("limited" and, placebo treatment "augmented" with a supportive patient-health care provider interaction. The primary outcome measure was change from baseline in IBS-Symptom Severity Scale (IBS-SSS after three weeks of treatment. In a regression model, the number of methionine alleles in COMT val158met was linearly related to placebo response as measured by changes in IBS-SSS (p = .035. The strongest placebo response occurred in met/met homozygotes treated in the augmented placebo arm. A smaller met/met associated effect was observed with limited placebo treatment and there was no effect in the waitlist control. These data support our hypothesis that the COMT val158met polymorphism is a potential biomarker of placebo response.
Catechol-O-methyltransferase (COMT) genotype biases neural correlates of empathy and perceived personal distress in schizophrenia.

Science.gov (United States)

Poletti, Sara; Radaelli, Daniele; Cavallaro, Roberto; Bosia, Marta; Lorenzi, Cristina; Pirovano, Adele; Smeraldi, Enrico; Benedetti, Francesco

2013-02-01

The catechol-O-methyltransferase (COMT) Val(108/158)Met polymorphism (rs4680) influences enzyme activity with valine (Val) allele associated with higher enzymatic activity. Several studies suggest that factors influencing dopaminergic transmission could control response to stressful situations. Empathy is an essential element of human behavior, requires the ability to adopt another person's perspective, and has been found to be dysfunctional in schizophrenia. Twenty-eight schizophrenic patients underwent functional magnetic resonance imaging performing an empathy task. Perceived empathy has been evaluated with the Interpersonal Reactivity Index. An effect of COMT on perceived distress subscale has been shown, with methionine (Met)/Met subjects reporting lower rates of stress compared with Val/Val. Moreover, imaging results showed an effect of genotype on empathy processing in the anterior cingulate with Val/Val subjects showing the lowest activation. This is the first study of the effect of rs4680 on interpersonal distress and neural correlates of empathy in schizophrenia. We found a decrease in neural responses in areas that ensure a cognitive control of emotion that is paralleled by perceived distress in interpersonal situation; this functional pattern seems to be influenced by rs4680 COMT polymorphism. Copyright © 2013 Elsevier Inc. All rights reserved.
Folate (vitamin B9) and vitamin B12 and their function in the maintenance of nuclear and mitochondrial genome integrity

International Nuclear Information System (INIS)

Fenech, Michael

2012-01-01

Folate plays a critical role in the prevention of uracil incorporation into DNA and hypomethylation of DNA. This activity is compromised when vitamin B12 concentration is low because methionine synthase activity is reduced, lowering the concentration of S-adenosyl methionine (SAM) which in turn may diminish DNA methylation and cause folate to become unavailable for the conversion of dUMP to dTMP. The most plausible explanation for the chromosome-breaking effect of low folate is excessive uracil misincorporation into DNA, a mutagenic lesion that leads to strand breaks in DNA during repair. Both in vitro and in vivo studies with human cells clearly show that folate deficiency causes expression of chromosomal fragile sites, chromosome breaks, excessive uracil in DNA, micronucleus formation, DNA hypomethylation and mitochondrial DNA deletions. In vivo studies show that folate and/or vitamin B12 deficiency and elevated plasma homocysteine (a metabolic indicator of folate deficiency) are significantly correlated with increased micronucleus formation and reduced telomere length respectively. In vitro experiments indicate that genomic instability in human cells is minimised when folic acid concentration in culture medium is greater than 100 nmol/L. Intervention studies in humans show (a) that DNA hypomethylation, chromosome breaks, uracil incorporation and micronucleus formation are minimised when red cell folate concentration is greater than 700 nmol/L and (b) micronucleus formation is minimised when plasma concentration of vitamin B12 is greater than 300 pmol/L and plasma homocysteine is less than 7.5 μmol/L. These concentrations are achievable at intake levels at or above current recommended dietary intakes of folate (i.e. >400 μg/day) and vitamin B12 (i.e. >2 μg/day) depending on an individual's capacity to absorb and metabolise these vitamins which may vary due to genetic and epigenetic differences.
Visualizing molecular juggling within a B[subscript 12]-dependent methyltransferase complex

Energy Technology Data Exchange (ETDEWEB)

Kung, Yan; Ando, Nozomi; Doukov, Tzanko I.; Blasiak, Leah C.; Bender, Güne; #351; ; Seravalli, Javier; Ragsdale, Stephen W.; Drennan, Catherine L. (MIT); (Michigan); (UNL)

2013-04-08

Derivatives of vitamin B{sub 12} are used in methyl group transfer in biological processes as diverse as methionine synthesis in humans and CO{sub 2} fixation in acetogenic bacteria. This seemingly straightforward reaction requires large, multimodular enzyme complexes that adopt multiple conformations to alternately activate, protect and perform catalysis on the reactive B{sub 12} cofactor. Crystal structures determined thus far have provided structural information for only fragments of these complexes, inspiring speculation about the overall protein assembly and conformational movements inherent to activity. Here we present X-ray crystal structures of a complete 220 kDa complex that contains all enzymes responsible for B{sub 12}-dependent methyl transfer, namely the corrinoid iron-sulphur protein and its methyltransferase from the model acetogen Moorella thermoacetica. These structures provide the first three-dimensional depiction of all protein modules required for the activation, protection and catalytic steps of B{sub 12}-dependent methyl transfer. In addition, the structures capture B{sub 12} at multiple locations between its 'resting' and catalytic positions, allowing visualization of the dramatic protein rearrangements that enable methyl transfer and identification of the trajectory for B{sub 12} movement within the large enzyme scaffold. The structures are also presented alongside in crystallo spectroscopic data, which confirm enzymatic activity within crystals and demonstrate the largest known conformational movements of proteins in a crystalline state. Taken together, this work provides a model for the molecular juggling that accompanies turnover and helps explain why such an elaborate protein framework is required for such a simple, yet biologically essential reaction.
Degradation of platinum based anticancer drugs by methionine: An EXAFS study

Energy Technology Data Exchange (ETDEWEB)

Provost, K; Bouvet-Muller, D; Michalowicz, A [ICMPE, UMR 7182 CNRS-Universite Paris 12, 94320 Thiais (France); Crauste-Manciet, S [Laboratoire de Pharmacie Galenique, Universite Paris Descartes, 75006 Paris (France); Olivi, L; Vlaic, G, E-mail: provost@univ-paris12.f [EXAFS Beamline, ELETTRA, Sincrotone Trieste, 34012 Basovizza, Trieste (Italy)

2009-11-15

We characterized the structures in solution of carboplatin and oxaliplatin degradation products in presence of a large excess of methionine (Met). The reaction of carboplatin leads to the formation of cis-Pt(Met){sub 2} while, in the case of oxaliplatin, methionine displaces only the oxalate ligand to form Pt(diaminocyclohexane)(Met).
Histone methyltransferase Setdb1 is indispensable for Meckel's cartilage development

International Nuclear Information System (INIS)

Yahiro, Kohei; Higashihori, Norihisa; Moriyama, Keiji

2017-01-01

The histone methyltransferase Setdb1 represses gene expression by catalyzing lysine 9 of histone H3 trimethylation. Given that the conventional knockout of Setdb1 is embryo-lethal at the implantation stage, its role in craniofacial development is poorly understood. Here, we investigated the role of Setdb1, using conditional knockout mice—in which Setdb1 was deleted in the Meckel's cartilage (Setdb1 CKO)—and the mouse chondrogenic cell line ATDC5—in which Setdb1 was inhibited by siRNA. Deletion of Setdb1 in Meckel's cartilage, the supportive tissue in the embryonic mandible, led to its enlargement, instead of the degeneration that normally occurs. Chondrocytes from the Meckel's cartilage of Setdb1 CKO mice showed increased size. Furthermore, at embryonic days 16.5 and 18.5, part of the perichondrium was disrupted and mineralization was observed in the Meckel's cartilage. Proliferation analysis showed that inhibition of Setdb1 caused increased proliferation in chondrocytes in the Meckel's cartilage as well as in ATDC5 cells. Quantitative RT-PCR showed decreased expression of chondrogenic genes, such as Sox9, Mmp13, Collagen II, and Aggrecan, as a result of Setdb1 inhibition in ATDC5 cells. Along with these phenomenons, SMAD-dependent BMP signaling was significantly increased by the loss of Setdb1 in both the Meckel's cartilage of Setdb1 CKO mice and ATDC5 cells. Therefore, the abnormal development of Meckel's cartilage in Setdb1 CKO mice is partly due to the enhanced SMAD-dependent BMP signaling. Overall, to our knowledge, the present study is the first to show that epigenetic regulation by Setdb1 is indispensable for the embryonic development of Meckel's cartilage. - Highlights: • Deletion of Setdb1 led to enlarged Meckel's cartilage. • Chondrocytes from the Meckel's cartilage of Setdb1 mutant showed increased in size. • Part of the perichondrium was disrupted and mineralization was observed in the Meckel's
Effects of sucrose on rFVIIa aggregation and methionine oxidation

DEFF Research Database (Denmark)

Soenderkaer, Susanne; Carpenter, John F; van de Weert, Marco

2004-01-01

The aim of this study was to characterize the effects of sucrose on the stability of recombinant factor VIIa (rFVIIa), with special emphasis on aggregation and methionine oxidation, as well as to investigate the impact of various environmental conditions on the rFVIIa conformation. The stability...... of rFVIIa was studied at pH 5. Aggregation was monitored using size exclusion high-performance liquid chromatography (SE-HPLC), whereas formation of methionine oxidation products was measured by reversed-phase high-performance liquid chromatography (RP-HPLC). Fourier transform infrared (FTIR...... the protein's surface, which shifts the protein molecular population away from expanded aggregation competent species and toward the compact native state, is thought to account for these observations. rFVIIa is sensitive to methionine oxidation; two mono-oxidized and one di-oxidized product were formed upon...
Porphyromonas gingivalis hydrogen sulfide enhances methyl mercaptan-induced pathogenicity in mouse abscess formation.

Science.gov (United States)

Nakamura, Suguru; Shioya, Koki; Hiraoka, B Yukihiro; Suzuki, Nao; Hoshino, Tomonori; Fujiwara, Taku; Yoshinari, Nobuo; Ansai, Toshihiro; Yoshida, Akihiro

2018-04-01

Porphyromonas gingivalis produces hydrogen sulfide (H2S) from l-cysteine. However, the role of H2S produced by P. gingivalis in periodontal inflammation is unclear. In this study, we identified the enzyme that catalyses H2S production from l-cysteine and analysed the role of H2S using a mouse abscess model. The enzyme identified was identical to methionine γ-lyase (PG0343), which produces methyl mercaptan (CH3SH) from l-methionine. Therefore, we analysed H2S and CH3SH production by P. gingivalis W83 and a PG0343-deletion mutant (ΔPG0343) with/without l-cysteine and/or l-methionine. The results indicated that CH3SH is produced constitutively irrespective of the presence of l-methionine, while H2S was greatly increased by both P. gingivalis W83 and ΔPG0343 in the presence of l-cysteine. In contrast, CH3SH production by ΔPG0343 was absent irrespective of the presence of l-methionine, and H2S production was eliminated in the absence of l-cysteine. Thus, CH3SH and H2S production involves different substrates, l-methionine or l-cysteine, respectively. Based on these characteristics, we analysed the roles of CH3SH and H2S in abscess formation in mice by P. gingivalis W83 and ΔPG0343. Abscess formation by P. gingivalis W83, but not ΔPG0343, differed significantly in the presence and absence of l-cysteine. In addition, the presence of l-methionine did not affect the size of abscesses generated by P. gingivalis W83 and ΔPG0343. Therefore, we conclude that H2S produced by P. gingivalis does not induce inflammation; however, H2S enhances inflammation caused by CH3SH. Thus, these results suggest the H2S produced by P. gingivalis plays a supportive role in inflammation caused by methionine γ-lyase.
Ferulic acid depletion by cultured soybean seedlings under action of glucose and methionine

Directory of Open Access Journals (Sweden)

Herrig Vanessa

2000-01-01

Full Text Available Cultured soybean seedlings were used to investigate how glucose or methionine influenced depletion of ferulic acid. Three-day-old seedlings were grown in hydroponic solution containing ferulic acid plus glucose or methionine, and the level of the phenolic acid were monitored in the nutrient culture. The results showed that ferulic acid depletion was more rapid in the presence of those compounds. After 6 h, the increase caused by glucose (0.01 and 0.05 mM was more pronounced than methionine in the same concentrations. On the other hand, methionine (0.1 and 0.2 mM increased depletion more significantly than glucose. Results suggested that both compounds might to increase the allelopathic effects of ferulic acid in the seedlings.
A Picrinine N-Methyltransferase Belongs to a New Family of γ-Tocopherol-Like Methyltransferases Found in Medicinal Plants That Make Biologically Active Monoterpenoid Indole Alkaloids1[OPEN

Science.gov (United States)

Levac, Dylan; Cázares, Paulo; Yu, Fang

2016-01-01

Members of the Apocynaceae plant family produce a large number of monoterpenoid indole alkaloids (MIAs) with different substitution patterns that are responsible for their various biological activities. A novel N-methyltransferase involved in the vindoline pathway in Catharanthus roseus showing distinct similarity to γ-tocopherol C-methyltransferases was used in a bioinformatic screen of transcriptomes from Vinca minor, Rauvolfia serpentina, and C. roseus to identify 10 γ-tocopherol-like N-methyltransferases from a large annotated transcriptome database of different MIA-producing plant species (www.phytometasyn.ca). The biochemical function of two members of this group cloned from V. minor (VmPiNMT) and R. serpentina (RsPiNMT) have been characterized by screening their biochemical activities against potential MIA substrates harvested from the leaf surfaces of MIA-accumulating plants. The approach was validated by identifying the MIA picrinine from leaf surfaces of Amsonia hubrichtii as a substrate of VmPiNMT and RsPiNMT. Recombinant proteins were shown to have high substrate specificity and affinity for picrinine, converting it to N-methylpicrinine (ervincine). Developmental studies with V. minor and R. serpentina showed that RsPiNMT and VmPiNMT gene expression and biochemical activities were highest in younger leaf tissues. The assembly of at least 150 known N-methylated MIAs within members of the Apocynaceae family may have occurred as a result of the evolution of the γ-tocopherol-like N-methyltransferase family from γ-tocopherol methyltransferases. PMID:26848097
Monolignol 4-O-methyltransferases and uses thereof

Science.gov (United States)

Liu, Chang-Jun; Bhuiya, Mohammad-Wadud; Zhang, Kewei

2014-11-18

Modified (iso)eugenol 4-O-methyltransferase enzymes having novel capacity for methylation of monolignols and reduction of lignin polymerization in plant cell wall are disclosed. Sequences encoding the modified enzymes are disclosed.
Abnormal maternal biomarkers of homocysteine and methionine ...

African Journals Online (AJOL)

Rabah M. Shawky

2017-09-15

Sep 15, 2017 ... homocysteine and methionine metabolism are altered among non pregnant women who ..... groups as regards history of smoking, exposure to environmental ..... anomalies from 1950 to 1994: an international perspective.

Structural and functional characteristics of cGMP-dependent methionine oxidation in Arabidopsis thaliana proteins

KAUST Repository

Marondedze, Claudius

2013-01-05

Background: Increasing structural and biochemical evidence suggests that post-translational methionine oxidation of proteins is not just a result of cellular damage but may provide the cell with information on the cellular oxidative status. In addition, oxidation of methionine residues in key regulatory proteins, such as calmodulin, does influence cellular homeostasis. Previous findings also indicate that oxidation of methionine residues in signaling molecules may have a role in stress responses since these specific structural modifications can in turn change biological activities of proteins. Findings. Here we use tandem mass spectrometry-based proteomics to show that treatment of Arabidopsis thaliana cells with a non-oxidative signaling molecule, the cell-permeant second messenger analogue, 8-bromo-3,5-cyclic guanosine monophosphate (8-Br-cGMP), results in a time-dependent increase in the content of oxidised methionine residues. Interestingly, the group of proteins affected by cGMP-dependent methionine oxidation is functionally enriched for stress response proteins. Furthermore, we also noted distinct signatures in the frequency of amino acids flanking oxidised and un-oxidised methionine residues on both the C- and N-terminus. Conclusions: Given both a structural and functional bias in methionine oxidation events in response to a signaling molecule, we propose that these are indicative of a specific role of such post-translational modifications in the direct or indirect regulation of cellular responses. The mechanisms that determine the specificity of the modifications remain to be elucidated. 2013 Marondedze et al.; licensee BioMed Central Ltd.
Involvement of methyltransferases enzymes during the energy

African Journals Online (AJOL)

Mgina

INVOLVEMENT OF METHYLTRANSFERASES ENZYMES DURING THE. ENERGY METABOLISM OF ..... cell extract still exhibited relatively high methanogenesis with methanol (Fig ... product CH3-CoM into methane (see Fig. 1). The HS-CoM ...
Methyltransferase Erm(37) Slips on rRNA to Confer Atypical Resistance in Mycobacterium tuberculosis

Czech Academy of Sciences Publication Activity Database

Madsen, Ch. T.; Jakobsen, L.; Buriánková, Karolína; Doucet-Populaire, F.; Perdonet, J. L.; Douthwaite, S.

2005-01-01

Roč. 280, č. 47 (2005), s. 38942-38947 ISSN 0021-9258 R&D Projects: GA ČR GA310/03/0292 Institutional research plan: CEZ:AV0Z50200510 Keywords : methyltransferase erm * mycobacterium tuberculosis * rRNA Subject RIV: EE - Microbiology, Virology Impact factor: 5.854, year: 2005
Overexpression of a soybean salicylic acid methyltransferase gene confers resistance to soybean cyst nematode

Science.gov (United States)

Salicylic acid plays a critical role in activating plant defence responses after pathogen attack. Salicylic acid methyltransferase (SAMT) modulates the level of salicylic acid by converting salicylic acid to methyl salicylate. Here, we report that a SAMT gene from soybean (GmSAMT1) plays a role in s...
Leishmania major methionine sulfoxide reductase A is required for resistance to oxidative stress and efficient replication in macrophages.

Directory of Open Access Journals (Sweden)

Fiona M Sansom

Full Text Available Leishmania are protozoan parasites that proliferate within the phagolysome of mammalian macrophages. While a number of anti-oxidant systems in these parasites have been shown to protect against endogenous as well as host-generated reactive oxygen species, the potential role of enzymes involved in the repair of oxidatively damaged proteins remains uncharacterized. The Leishmania spp genomes encode a single putative methionine sulfoxide reductase (MsrA that could have a role in reducing oxidized free and proteinogenic methionine residues. A GFP-fusion of L. major MsrA was shown to have a cytoplasmic localization by immunofluorescence microscopy and subcellular fractionation. An L. major msrA null mutant, generated by targeted replacement of both chromosomal allelles, was viable in rich medium but was unable to reduce exogenous methionine sulfoxide when cultivated in the presence of this amino acid, indicating that msrA encodes a functional MsrA. The ΔmsrA mutant exhibited increased sensitivity to H(2O(2 compared to wild type parasites and was unable to proliferate normally in macrophages. Wild type sensitivity to H(2O(2 and infectivity in macrophages was restored by complementation of the mutant with a plasmid encoding MsrA. Unexpectedly, the ΔmsrA mutant was able to induce normal lesions in susceptible BALB/c indicating that this protein is not essential for pathogenesis in vivo. Our results suggest that Leishmania MsrA contributes to the anti-oxidative defences of these parasites, but that complementary oxidative defence mechansims are up-regulated in lesion amastigotes.
GNMT Expression Increases Hepatic Folate Contents and Folate-Dependent Methionine Synthase-Mediated Homocysteine Remethylation

OpenAIRE

Wang, Yi-Cheng; Chen, Yi-Ming; Lin, Yan-Jun; Liu, Shih-Ping; Chiang, En-Pei Isabel

2011-01-01

Glycine N-methyltransferase (GNMT) is a major hepatic enzyme that converts S-adenosylmethionine to S-adenosylhomocysteine while generating sarcosine from glycine, hence it can regulate mediating methyl group availability in mammalian cells. GNMT is also a major hepatic folate binding protein that binds to, and, subsequently, may be inhibited by 5-methyltetrafolate. GNMT is commonly diminished in human hepatoma; yet its role in cellular folate metabolism, in tumorigenesis and antifolate therap...
Methyl group balance in brain and liver: role of choline on increased S-adenosyl methionine (SAM) demand by chronic arsenic exposure.

Science.gov (United States)

Ríos, Rosalva; Santoyo, Martha E; Cruz, Daniela; Delgado, Juan Manuel; Zarazúa, Sergio; Jiménez-Capdeville, María E

2012-11-30

Arsenic toxicity has been related to its interference with one carbon metabolism, where a high demand of S-adenosylmethionine (SAM) for arsenic methylation as well as a failure of its regeneration would compromise the availability of methyl groups for diverse cellular functions. Since exposed animals show disturbances of methylated products such as methylated arginines, myelin and axon membranes, this work investigates whether alterations of SAM, choline and phosphatidylcholine (PC) in the brain of arsenic exposed rats are associated with myelin alterations and myelin basic protein (MBP) immunoreactivity. Also these metabolites, morphologic and biochemical markers of methyl group alterations were analyzed in the liver, the main site of arsenic methylation. In adult, life-long arsenic exposed rats through drinking water (3 ppm), no changes of SAM, choline and PC concentrations where found in the brain, but SAM and PC were severely decreased in liver accompanied by a significant increase of choline. These results suggest that choline plays an important role as methyl donor in arsenic exposure, which could underlie hepatic affections observed when arsenic exposure is combined with other environmental factors. Also, important myelin and nerve fiber alterations, accompanied by a 75% decrease of MBP immunoreactivity were not associated with a SAM deficit in the brain. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
A viral protein promotes host SAMS1 activity and ethylene production for the benefit of virus infection.

Science.gov (United States)

Zhao, Shanshan; Hong, Wei; Wu, Jianguo; Wang, Yu; Ji, Shaoyi; Zhu, Shuyi; Wei, Chunhong; Zhang, Jinsong; Li, Yi

2017-10-10

Ethylene plays critical roles in plant development and biotic stress response, but the mechanism of ethylene in host antiviral response remains unclear. Here, we report that Rice dwarf virus (RDV) triggers ethylene production by stimulating the activity of S-adenosyl-L-methionine synthetase (SAMS), a key component of the ethylene synthesis pathway, resulting in elevated susceptibility to RDV. RDV-encoded Pns11 protein specifically interacted with OsSAMS1 to enhance its enzymatic activity, leading to higher ethylene levels in both RDV-infected and Pns11-overexpressing rice. Consistent with a counter-defense role for ethylene, Pns11-overexpressing rice, as well as those overexpressing OsSAMS1 , were substantially more susceptible to RDV infection, and a similar effect was observed in rice plants treated with an ethylene precursor. Conversely, OsSAMS1- knockout mutants, as well as an osein2 mutant defective in ethylene signaling, resisted RDV infection more robustly. Our findings uncover a novel mechanism which RDV manipulates ethylene biosynthesis in the host plants to achieve efficient infection.
Assay method and compositions

International Nuclear Information System (INIS)

1977-01-01

Methods are described for measuring catecholamine levels in human and animal body fluids and tissues using the catechol-O-methyl-transferase (COMT) radioassay. The assay involves incubating the biological sample with COMT and the tritiated methyl donor, S-adenosyl-L-methionine( 3 H)-methyl. The O-methylated ( 3 H) epinephrine and/or norepinephrine are extracted and oxidised to vanillin- 3 H which in turn is extracted and its radioactivity counted. When analysing dopamine levels the assay is extended by vanillin- 3 H and raising the pH of the aqueous periodate phase from which O-methylated ( 3 H) dopamine is extracted and counted. The assay may be modified depending on whether measurements of undifferentiated total endogenous catecholamine levels or differential analyses of the catecholamine levels are being performed. The sensitivity of the assay can be as low as 5 picograms for norepinephrine and epinephrine and 12 picograms for dopamine. The assemblance of the essential components of the assay into a kit for use in laboratories is also described. (U.K.)
Methionine supplementation influences melanin-based plumage colouration in Eurasian kestrel, Falco tinnunculus, nestlings.

Science.gov (United States)

Parejo, Deseada; Silva, Nadia

2009-11-01

The extent to which the expression of melanin-based plumage colouration in birds is genetically or environmentally determined is controversial. Here, we performed a between-nest design supplementation with either the sulphur amino acid dl-methionine or with water to investigate the importance of the non-genetic component of melanin-based plumage colouration in the Eurasian kestrel, Falco tinnunculus. Methionine affects growth and immunity, thus we aimed to modify nestling growth and immunity before feather development. Then, we measured the effect of the experiment on colouration of two melanin-based plumage patches of nestling kestrels. We found that methionine slowed down nestling growth through treatment administration and that nestlings compensated by speeding up their growth later. We did not find any effects of methionine on nestling immunity (i.e. lymphocyte counts, natural antibody levels or complement-mediated immunity). Effects on growth seemed to be mirrored by changes in nestling colouration in the two sexes: methionine-nestlings showed less intense brown plumage on their backs compared with control nestlings. These results provide support for a non-genetic determination of a melanin-based plumage patch in the two sexes of nestling kestrels.
CONCENTRATION-DEPENDENT LINKAGE OF DIETARY METHIONINE RESTRICTION TO THE COMPONENTS OF ITS METABOLIC PHENOTYPE

OpenAIRE

Forney, Laura A.; Wanders, Desiree; Stone, Kirsten P.; Pierse, Alicia; Gettys, Thomas W.

2017-01-01

Objective Restricting dietary methionine to 0.17% produces a series of physiological responses through coordinated transcriptional effects in liver and adipose tissue. The goal of the present work was to determine the threshold concentrations above and below 0.17% at which the beneficial responses to 0.17% dietary methionine are preserved. Methods Diets were formulated to restrict methionine to different degrees, followed by evaluation of the transcriptional and physiological responses to the...
Tyrosine 87 is vital for the activity of human protein arginine methyltransferase 3 (PRMT3)

Czech Academy of Sciences Publication Activity Database

Handrková, H.; Petrák, J.; Halada, Petr; Pospíšilová, D.; Čmejla, R.

2011-01-01

Roč. 1814, č. 2 (2011), s. 277-282 ISSN 1570-9639 R&D Projects: GA MŠk LC07017 Institutional research plan: CEZ:AV0Z50200510 Keywords : DIAMOND-BLACKFAN ANEMIA * SUBSTRATE -SPECIFICITY * N-METHYLTRANSFERASE Subject RIV: CE - Biochemistry Impact factor: 3.635, year: 2011
Characterization of a SAM-dependent fluorinase from a latent biosynthetic pathway for fluoroacetate and 4-fluorothreonine formation in Nocardia brasiliensis.

Science.gov (United States)

Wang, Yaya; Deng, Zixin; Qu, Xudong

2014-01-01

Fluorination has been widely used in chemical synthesis, but is rare in nature. The only known biological fluorination scope is represented by the fl pathway from Streptomyces cattleya that produces fluoroacetate (FAc) and 4-fluorothreonine (4-FT). Here we report the identification of a novel pathway for FAc and 4-FT biosynthesis from the actinomycetoma-causing pathogen Nocardia brasiliensis ATCC 700358. The new pathway shares overall conservation with the fl pathway in S. cattleya. Biochemical characterization of the conserved domains revealed a novel fluorinase NobA that can biosynthesize 5'-fluoro-5'-deoxyadenosine (5'-FDA) from inorganic fluoride and S-adenosyl-l-methionine (SAM). The NobA shows similar halide specificity and characteristics to the fluorination enzyme FlA of the fl pathway. Kinetic parameters for fluoride ( K m 4153 μM, k cat 0.073 min (-1)) and SAM ( K m 416 μM, k cat 0.139 min (-1)) have been determined, revealing that NobA is slightly (2.3 fold) slower than FlA. Upon sequence comparison, we finally identified a distinct loop region in the fluorinases that probably accounts for the disparity of fluorination activity.
Characterization of a SAM-dependent fluorinase from a latent biosynthetic pathway for fluoroacetate and 4-fluorothreonine formation in Nocardia brasiliensis [v1; ref status: indexed, http://f1000r.es/2tz

Directory of Open Access Journals (Sweden)

Yaya Wang

2014-02-01

Full Text Available Fluorination has been widely used in chemical synthesis, but is rare in nature. The only known biological fluorination scope is represented by the fl pathway from Streptomyces cattleya that produces fluoroacetate (FAc and 4-fluorothreonine (4-FT. Here we report the identification of a novel pathway for FAc and 4-FT biosynthesis from the actinomycetoma-causing pathogen Nocardia brasiliensis ATCC 700358. The new pathway shares overall conservation with the fl pathway in S. cattleya. Biochemical characterization of the conserved domains revealed a novel fluorinase NobA that can biosynthesize 5’-fluoro-5’-deoxyadenosine (5’-FDA from inorganic fluoride and S-adenosyl-l-methionine (SAM. The NobA shows similar halide specificity and characteristics to the fluorination enzyme FlA of the fl pathway. Kinetic parameters for fluoride (Km 4153 μM, kcat 0.073 min-1 and SAM (Km 416 μM, kcat 0.139 min-1 have been determined, revealing that NobA is slightly (2.3 fold slower than FlA. Upon sequence comparison, we finally identified a distinct loop region in the fluorinases that probably accounts for the disparity of fluorination activity.
Geochemical behaviour of palladium in soils and Pd/PdO model substances in the presence of the organic complexing agents L-methionine and citric acid.

Science.gov (United States)

Zereini, Fathi; Wiseman, Clare L S; Vang, My; Albers, Peter; Schneider, Wolfgang; Schindl, Roland; Leopold, Kerstin

2016-01-01

Risk assessments of platinum group metal (PGE) emissions, notably those of platinum (Pt), palladium (Pd) and rhodium (Rh), have been mostly based on data regarding the metallic forms used in vehicular exhaust converters, known to be virtually biologically inert and immobile. To adequately assess the potential impacts of PGE, however, data on the chemical behaviour of these metals under ambient conditions post-emission is needed. Complexing agents with a high affinity for metals in the environment are hypothesized to contribute to an increased bioaccessibility of PGE. The purpose of this study is to examine the modulating effects of the organic complexing agents, L-methionine and citric acid, on the geochemical behavior of Pd in soils and model substances (Pd black and PdO). Batch experimental tests were conducted with soils and model substances to examine the impacts of the concentration of complexing agents, pH and length of extraction period on Pd solubility and its chemical transformation. Particle surface chemistry was examined using X-ray photoelectron spectroscopy (XPS) on samples treated with solutions under various conditions, including low and high O2 levels. Pd was observed to be more soluble in the presence of organic complexing agents, compared to Pt and Rh. Pd in soils was more readily solubilized with organic complexing agents compared to the model substances. After 7 days of extraction, L-methionine (0.1 M) treated soil and Pd black samples, for instance, had mean soluble Pd fractions of 12.4 ± 5.9% and 0.554 ± 0.024%, respectively. Surface chemistry analyses (XPS) confirmed the oxidation of metallic Pd surfaces when treated with organic complexing agents. The type of organic complexing agent used for experimental purposes was observed to be the most important factor influencing solubility, followed by solution pH and time of extraction. The results demonstrate that metallic Pd can be transformed into more bioaccessible species in the presence of
The O-methyltransferase PMT2 mediates methylation of pinosylvin in Scots pine.

Science.gov (United States)

Paasela, Tanja; Lim, Kean-Jin; Pietiäinen, Milla; Teeri, Teemu H

2017-06-01

Heartwood extractives are important determinants of the natural durability of pine heartwood. The most important phenolic compounds affecting durability are the stilbenes pinosylvin and its monomethylether, which in addition have important functions as phytoalexins in active defense. A substantial portion of the synthesized pinosylvin is 3-methoxylated but the O-methyltransferase responsible for this modification has not been correctly identified. We studied the expression of the stilbene pathway during heartwood development as well as in response to wounding of xylem and UV-C treatment of needles. We isolated and enzymatically characterized a novel O-methyltransferase, PMT2. The methylated product was verified as pinosylvin monomethylether using ultra performance liquid chromatography-tandem mass spectrometry and high performance liquid chromatography analyses. The PMT2 enzyme was highly specific for stilbenes as substrate, in contrast to caffeoyl-CoA O-methyltransferase (CCoAOMT) and PMT1 that were multifunctional. Expression profile and multifunctional activity of CCoAOMT suggest that it might have additional roles outside lignin biosynthesis. PMT1 is not involved in the stilbene pathway and its biological function remains an open question. We isolated a new specific O-methyltransferase responsible for 3-methoxylation of pinosylvin. Expression of PMT2 closely follows stilbene biosynthesis during developmental and stress induction. We propose that PMT2 is responsible for pinosylvin methylation in Scots pine (Pinus sylvestris), instead of the previously characterized methyltransferase, PMT1. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
Influence of protein level and supplemental methionine in practical rations for young endangered masked bobwhite quail

Science.gov (United States)

Serafin, J.A.

1982-01-01

A study was conducted to examine the protein requirement of young endangered masked Bobwhite quail (Colinus virginianus ridgwayi). Five practical starting rations containing 24 to 32% protein were fed alone and supplemented with methionine for 5 weeks. Supplemental methionine significantly improved growth of quail fed diets containing 24 and 26% protein. Increasing the protein level improved growth of quail fed unsupplemented diets but did not do so when diets contained supplemental methionine. A methionine-supplemented ration containing 24% protein appeared adequate for supporting rapid growth of masked Bobwhite quail.
Tissue methionine cycle activity and homocysteine metabolism in female rats: impact of dietary methionine and folate plus choline

NARCIS (Netherlands)

Wilson, F.A.; Borne, van den J.J.G.C.; Calder, A.G.; O'Kennedy, N.; Holtrop, G.; Rees, W.D.; Lobley, G.E.

2009-01-01

Impaired transfer of methyl groups via the methionine cycle leads to plasma hyperhomocysteinemia. The tissue sources of plasma homocysteine in vivo have not been quantified nor whether hyperhomocysteinemia is due to increased entry or decreased removal. These issues were addressed in female rats
Independent and additive effects of glutamic acid and methionine on yeast longevity.

Science.gov (United States)

Wu, Ziyun; Song, Lixia; Liu, Shao Quan; Huang, Dejian

2013-01-01

It is established that glucose restriction extends yeast chronological and replicative lifespan, but little is known about the influence of amino acids on yeast lifespan, although some amino acids were reported to delay aging in rodents. Here we show that amino acid composition greatly alters yeast chronological lifespan. We found that non-essential amino acids (to yeast) methionine and glutamic acid had the most significant impact on yeast chronological lifespan extension, restriction of methionine and/or increase of glutamic acid led to longevity that was not the result of low acetic acid production and acidification in aging media. Remarkably, low methionine, high glutamic acid and glucose restriction additively and independently extended yeast lifespan, which could not be further extended by buffering the medium (pH 6.0). Our preliminary findings using yeasts with gene deletion demonstrate that glutamic acid addition, methionine and glucose restriction prompt yeast longevity through distinct mechanisms. This study may help to fill a gap in yeast model for the fast developing view that nutrient balance is a critical factor to extend lifespan.
Chemical speciation of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II binary complexes of l-methionine in 1,2-propanediol-water mixtures

Directory of Open Access Journals (Sweden)

M. Padma Latha

2007-04-01

Full Text Available Chemical speciation of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II complexes of L-methionine in 0.0-60 % v/v 1,2-propanediol-water mixtures maintaining an ionic strength of 0.16 M at 303 K has been studied pH metrically. The active forms of ligand are LH2+, LH and L-. The predominant species detected are ML, MLH, ML2, ML2H, ML2H2 and MLOH. Models containing different numbers of species were refined by using the computer program MINIQUAD 75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of complex stability constants with change in the dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces.

Feed efficiency of diets with different energy and protein concentrations supplemented with methionine in laying quails

Science.gov (United States)

Ratriyanto, A.; Indreswari, R.; Nuhriawangsa, A. M. P.; Purwanti, E.

2018-03-01

The study was conducted to evaluate the feed efficiency of quail diets containing different concentrations of metabolizable energy (ME) and crude protein (CP) with constant ratio and supplemented with methionine. Four hundred laying quails (Coturnix coturnix japonica) were randomly assigned to four experimental diets in a 2×2 factorial arrangement. Each dietary treatment used 5 replicates of 20 quails. Two basal diets were formulated to contain 2,800 kcal kg-1 ME and 18.7% CP (High ME-CP) and 2,600 kcal kg-1 ME and 17.3% CP (Low ME-CP). Each basal diet was supplemented with 0 and 0.12% methionine. The High ME-CP diets generated lower feed consumption but higher egg mass and feed efficiency (Pprotein efficiency ratio (PHigh ME-CP supplemented with methionine resulted the highest feed efficiency followed by the Low ME-CP supplemented with methionine, while both High ME-CP and Low ME-CP without methionine supplementation resulted the lowest feed efficiency (PHigh ME-CP supplemented with 0.12% methionine provided benefit to improve the feed efficiency in laying quails.
Individual radiation response of parotid glands investigated by dynamic 11C-methionine PET

International Nuclear Information System (INIS)

Buus, Simon; Grau, Cai; Munk, Ole Lajord; Rodell, Anders; Jensen, Kenneth; Mouridsen, Kim; Keiding, Susanne

2006-01-01

Background and Purpose: Previously, we showed that the net metabolic clearance of 11 C-methionine of the parotid gland, K, calculated from dynamic 11 C-methionine PET, can be used as a measure of parotid gland function. The aim of this study was to investigate by dynamic 11 C-methionine PET the individual radiation dose response relationship of parotid glands in head and neck cancer patients. Patients and methods: Twelve head and neck cancer patients were examined by dynamic 11 C-methionine PET after radiotherapy. Parametric images of K were generated, co-registered and compared voxel-by-voxel with the 3D radiation dose plan within the parotid gland to assess the individual radiation dose-function relationship. Results: In each patient, voxel-values of K decreased with increasing radiation dose. Population based analysis showed a sigmoid dose response relationship of parotid gland, from which we estimated a threshold radiation dose of 16 Gy and a mean TD 5 of 30 Gy. TD 5 ranged from 7 to 50 Gy in the group of patients. Conclusions: Individual radiation dose response of parotid glands can be measured by dynamic 11 C-methionine PET. The dose response analysis revealed a sigmoid relationship, a threshold radiation dose of 16 Gy, and a mean TD 5 of 30 Gy
Preclinical evaluation of an {sup 18}F-trifluoroborate methionine derivative for glioma imaging

Energy Technology Data Exchange (ETDEWEB)

Yang, Xiangyu [Medical School of Southeast University, Jiangsu Key Laboratory of Molecular Imaging and Functional Imaging, Department of Radiology, Zhongda Hospital, Nanjing (China); National Institutes of Health (NIH), Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD (United States); Liu, Zhibo; Zhang, Huimin; Li, Zhu; Niu, Gang; Chen, Xiaoyuan [National Institutes of Health (NIH), Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD (United States); Munasinghe, Jeeva P. [NIH, Mouse Imaging Facility, National Institute of Neurological Disorders and Stroke, Bethesda, MD (United States); Teng, Gaojun [Medical School of Southeast University, Jiangsu Key Laboratory of Molecular Imaging and Functional Imaging, Department of Radiology, Zhongda Hospital, Nanjing (China)

2018-04-15

{sup 11}C-methionine (MET) is one of the most commonly used amino acid tracers for PET imaging of brain tumors. In this study, we report an {sup 18}F-labeled boron-derived methionine analogue, denoted as {sup 18}F-B-MET, as a potential substitute of {sup 11}C-MET for glioma PET imaging. {sup 19}F-B-MET was synthesized from readily available chemicals according to our previous publication. For kit development, {sup 19}F-B-MET was aliquoted in quantities of 10 nmol for on-demand one-step labeling. The {sup 18}F-labeling was performed by {sup 18}F-{sup 19}F isotope exchange, and quality control was performed by both HPLC and radio-TLC. Uptake of the tracer was determined in GL26, C6 and U87 tumor cells. PET imaging and the biodistribution assay were performed on mice bearing subcutaneous or orthotopic C6 and U87 tumor xenografts. Starting with 740-1110 MBq {sup 18}F-fluoride, >370 MBq of {sup 18}F-B-MET was obtained in 25 min (n = 5) with >99% purity and high specific activity (>37 GBq/μmol). {sup 18}F-B-MET demonstrated excellent in vitro stability with <1% decomposition after incubation with plasma for 2 h. In vitro cell uptake assay showed that {sup 18}F-B-MET accumulated in tumor cells in a time dependent manner and could be competitively inhibited by natural methionine and other L-type transporter transported amino acids. In vivo biodistribution and imaging studies showed high tumor accumulation (2.99 ± 0.23 %ID/g, n = 6) compared with low uptake of brain (0.262 ± 0.05 %ID/g, n = 6) at 60 min after injection in a subcutaneous C6 tumor model. Orthotropic C6 and U87 tumors were clearly visualized with high tumor to brain ratios at 60 min post-injection, corroborating with tumor L-type amino acid transporter 1 (LAT-1) expression levels. {sup 18}F-B-MET was radiolabeled with high yield in a one-step labeling process, showed excellent pharmacokinetic properties in vivo, with high tumor-to-brain contrast. (orig.)
The Role of a Novel TRMT1 Gene Mutation and Rare GRM1 Gene Defect in Intellectual Disability in Two Azeri Families

Science.gov (United States)

Kahrizi, Kimia; Musante, Luciana; Fattahi, Zohreh; Hosseini, Masoumeh; Maqsoud, Fariba; Farajollahi, Reza; Wienker, Thomas F.; Ropers, H. Hilger; Najmabadi, Hossein

2015-01-01

Cognitive impairment or intellectual disability (ID) is a widespread neurodevelopmental disorder characterized by low IQ (below 70). ID is genetically heterogeneous and is estimated to affect 1–3% of the world’s population. In affected children from consanguineous families, autosomal recessive inheritance is common, and identifying the underlying genetic cause is an important issue in clinical genetics. In the framework of a larger project, aimed at identifying candidate genes for autosomal recessive intellectual disorder (ARID), we recently carried out single nucleotide polymorphism-based genome-wide linkage analysis in several families from Ardabil province in Iran. The identification of homozygosity-by-descent loci in these families, in combination with whole exome sequencing, led us to identify possible causative homozygous changes in two families. In the first family, a missense variant was found in GRM1 gene, while in the second family, a frameshift alteration was identified in TRMT1, both of which were found to co-segregate with the disease. GRM1, a known causal gene for autosomal recessive spinocerebellar ataxia (SCAR13, MIM#614831), encodes the metabotropic glutamate receptor1 (mGluR1). This gene plays an important role in synaptic plasticity and cerebellar development. Conversely, the TRMT1 gene encodes a tRNA methyltransferase that dimethylates a single guanine residue at position 26 of most tRNAs using S-adenosyl methionine as the methyl group donor. We recently presented TRMT1 as a candidate gene for ARID in a consanguineous Iranian family (Najmabadi et al., 2011). We believe that this second Iranian family with a biallelic loss-of-function mutation in TRMT1 gene supports the idea that this gene likely has function in development of the disorder. PMID:26308914
Characterization of Timed Changes in Hepatic Copper Concentrations, Methionine Metabolism, Gene Expression, and Global DNA Methylation in the Jackson Toxic Milk Mouse Model of Wilson Disease

Directory of Open Access Journals (Sweden)

Anh Le

2014-05-01

Full Text Available Background: Wilson disease (WD is characterized by hepatic copper accumulation with progressive liver damage to cirrhosis. This study aimed to characterize the toxic milk mouse from The Jackson Laboratory (Bar Harbor, ME, USA (tx-j mouse model of WD according to changes over time in hepatic copper concentrations, methionine metabolism, global DNA methylation, and gene expression from gestational day 17 (fetal to adulthood (28 weeks. Methods: Included liver histology and relevant biochemical analyses including hepatic copper quantification, S-adenosylmethionine (SAM and S-adenosylhomocysteine (SAH liver levels, qPCR for transcript levels of genes relevant to methionine metabolism and liver damage, and DNA dot blot for global DNA methylation. Results: Hepatic copper was lower in tx-j fetuses but higher in weanling (three weeks and adult tx-j mice compared to controls. S-adenosylhomocysteinase transcript levels were significantly lower at all time points, except at three weeks, correlating negatively with copper levels and with consequent changes in the SAM:SAH methylation ratio and global DNA methylation. Conclusion: Compared to controls, methionine metabolism including S-adenosylhomocysteinase gene expression is persistently different in the tx-j mice with consequent alterations in global DNA methylation in more advanced stages of liver disease. The inhibitory effect of copper accumulation on S-adenosylhomocysteinase expression is associated with progressively abnormal methionine metabolism and decreased methylation capacity and DNA global methylation.
Cobalamin inactivation by nitrous oxide produces severe neurological impairment in fruit bats: protection by methionine and aggravation by folates

Energy Technology Data Exchange (ETDEWEB)

van der Westhuyzen, J.; Fernandes-Costa, F.; Metz, J.

1982-11-01

Nitrous oxide, which inactivates cobalamin when administered to fruit bats, results in severe neurological impairment leading to ataxia, paralysis and death. This occurs after about 6 weeks in animals depleted of cobalamin by dietary restriction, and after about 10 weeks in cobalamin replete bats. Supplementation of the diet with pteroylglutamic acid caused acceleration of the neurological impairment--the first unequivocal demonstration of aggravation of the neurological lesion in cobalamin deficiency by pteroylglutamic acid. The administration of formyltetrahydropteroylglutamic acid produced similar aggravation of the neurological lesion. Supplementation of the diet with methionine protected the bats from neurological impairment, but failed to prevent death. Methionine supplementation protected against the exacerbating effect of folate, preventing the development of neurological changes. These findings lend support to the hypothesis that the neurological lesion in cobalamin deficiency may be related to a deficiency in the methyl donor S-adenosylmethionine which follows diminished synthesis of methionine.
A role for 11C-methionine PET imaging in ACTH-dependent Cushing's syndrome.

Science.gov (United States)

Koulouri, Olympia; Steuwe, Andrea; Gillett, Daniel; Hoole, Andrew C; Powlson, Andrew S; Donnelly, Neil A; Burnet, Neil G; Antoun, Nagui M; Cheow, Heok; Mannion, Richard J; Pickard, John D; Gurnell, Mark

2015-10-01

We report our experience of functional imaging with (11)C-methionine positron emission tomography-computed tomography (PET-CT) co-registered with 3D gradient echo (spoiled gradient recalled (SPGR)) magnetic resonance imaging (MRI) in the investigation of ACTH-dependent Cushing's syndrome. Twenty patients with i) de novo Cushing's disease (CD, n=10), ii) residual or recurrent hypercortisolism following first pituitary surgery (±radiotherapy; n=8) or iii) ectopic Cushing's syndrome (n=2) were referred to our centre for functional imaging studies between 2010 and 2015. Six of the patients with de novo CD and five of those with persistent/relapsed disease had a suspected abnormality on conventional MRI. All patients underwent (11)C-methionine PET-CT. For pituitary imaging, co-registration of PET-CT images with contemporaneous SPGR MRI (1 mm slice thickness) was performed, followed by detailed mapping of (11)C-methionine uptake across the sella in three planes (coronal, sagittal and axial). This allowed us to determine whether suspected adenomas seen on structural imaging exhibited focal tracer uptake on functional imaging. In seven of ten patients with de novo CD, asymmetric (11)C-methionine uptake was observed within the sella, which co-localized with the suspected site of a corticotroph microadenoma visualised on SPGR MRI (and which was subsequently confirmed histologically following successful transsphenoidal surgery (TSS)). Focal (11)C-methionine uptake that correlated with a suspected abnormality on pituitary MRI was seen in five of eight patients with residual or recurrent Cushing's syndrome following first TSS (and pituitary radiotherapy in two cases). Two patients elected to undergo repeat TSS with histology confirming a corticotroph tumour in each case. In two patients with the ectopic ACTH syndrome, (11)C-methionine was concentrated in sites of distant metastases, with minimal uptake in the sellar region. (11)C-methionine PET-CT can aid the detection of
[Folates and fetal programming: role of epigenetics and epigenomics].

Science.gov (United States)

Guéant, Jean-Louis; Daval, Jean-Luc; Vert, Paul; Nicolas, Jean-Pierre

2012-12-01

Folates are needed for synthesis of methionine, the precursor of S-adenosyl methionine (SAM). They play therefore a key role in nutrition and epigenomics by fluxing monocarbons towards synthesis or methylation of DNA and RNA, and methylation of gene transregulators, respectively. The deficiency produces intrauterine growth retardation and birth dejects. Folate deficiency deregulates epigenomic mechanisms related to fetal programming through decreased cellular availability of SAM. Epigenetic mechanisms of folate deficiency are illustrated by inheritance of coat colour of agouti mice model and altered expression of Igf2/H19 imprinting genes. Dietary exposure to fumonisin FB1 acts synergistically with folate deficiency on alterations of heterochromatin assembly. Deficiency in folate and vitamin B12 produces impaired fatty acid oxidation in liver and heart through imbalanced methylation and acetylation of PGC1-alpha and decreased expression of SIRT1, and long-lasting cognitive disabilities through impaired hippocampal cell proliferation, differentiation and plasticity and atrophy of hippocampal CA1. Deciphering these mechanisms will help understand the discordances between experimental models and population studies on folate supplementation.
One-step synthesis of an {sup 18}F-labeled boron-derived methionine analog. A substitute for {sup 11}C-methionine?

Energy Technology Data Exchange (ETDEWEB)

Liu, Zhen; Lan, Xiaoli [Huazhong University of Science and Technology, Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Wuhan (China); Huazhong University of Science and Technology, Hubei Key Laboratory of Molecular Imaging, Union Hospital, Tongji Medical College, Wuhan (China); Ehlerding, Emily B. [University of Wisconsin - Madison, Department of Medical Physics, Madison, WI (United States); Cai, Weibo [University of Wisconsin - Madison, Department of Medical Physics, Madison, WI (United States); University of Wisconsin - Madison, Department of Radiology, Madison, WI (United States); University of Wisconsin - Madison, Carbone Cancer Center, Madison, WI (United States)

2018-04-15

Amino acid-based tracers have been extensively investigated for positron emission tomography (PET) imaging of brain tumors, and {sup 11}C-methionine ({sup 11}C-MET) is one of the most extensively investigated. However, widespread clinical use of {sup 11}C-MET is challenging due to the short half-life of {sup 11}C and low radiolabeling yield. In this issue of the European Journal of Nuclear Medicine and Molecular Imaging, Yang and colleagues report an {sup 18}F-labeled boron-derived methionine analog, {sup 18}F-B-MET, as a potential substitute for {sup 11}C-MET in PET imaging of glioma. The push-button synthesis, highly efficient radiolabeling, and good imaging performance in glioma models make this tracer a promising candidate for future clinical translation. (orig.)
The Role of a Novel TRMT1 Gene Mutation and Rare GRM1 Gene Defect in Intellectual Disability in Two Azeri Families.

Science.gov (United States)

Davarniya, Behzad; Hu, Hao; Kahrizi, Kimia; Musante, Luciana; Fattahi, Zohreh; Hosseini, Masoumeh; Maqsoud, Fariba; Farajollahi, Reza; Wienker, Thomas F; Ropers, H Hilger; Najmabadi, Hossein

2015-01-01

Cognitive impairment or intellectual disability (ID) is a widespread neurodevelopmental disorder characterized by low IQ (below 70). ID is genetically heterogeneous and is estimated to affect 1-3% of the world's population. In affected children from consanguineous families, autosomal recessive inheritance is common, and identifying the underlying genetic cause is an important issue in clinical genetics. In the framework of a larger project, aimed at identifying candidate genes for autosomal recessive intellectual disorder (ARID), we recently carried out single nucleotide polymorphism-based genome-wide linkage analysis in several families from Ardabil province in Iran. The identification of homozygosity-by-descent loci in these families, in combination with whole exome sequencing, led us to identify possible causative homozygous changes in two families. In the first family, a missense variant was found in GRM1 gene, while in the second family, a frameshift alteration was identified in TRMT1, both of which were found to co-segregate with the disease. GRM1, a known causal gene for autosomal recessive spinocerebellar ataxia (SCAR13, MIM#614831), encodes the metabotropic glutamate receptor1 (mGluR1). This gene plays an important role in synaptic plasticity and cerebellar development. Conversely, the TRMT1 gene encodes a tRNA methyltransferase that dimethylates a single guanine residue at position 26 of most tRNAs using S-adenosyl methionine as the methyl group donor. We recently presented TRMT1 as a candidate gene for ARID in a consanguineous Iranian family (Najmabadi et al., 2011). We believe that this second Iranian family with a biallelic loss-of-function mutation in TRMT1 gene supports the idea that this gene likely has function in development of the disorder.
Influence of dietary protein and excess methionine on choline needs for young bobwhite quail

Science.gov (United States)

Serafin, J.A.

1982-01-01

Experiments were conducted with young Bobwhite quail (Colinus virginianus) to investigate the effect of differing dietary protein levels and nondetrimental amounts of excess methionine on choline needs. Growth and feed consumption of quail fed an adequate (27.3%) protein purified diet supplemented with 2000 mg/kg of choline were unaffected by increasing the level of excess methionine to 1.75%; however, greater amounts (2.0%, 2.25%) of excess methionine depressed growth (P less than .01), reduced feed consumption (P less than .01), and decreased feed utilization (P less than .05). Quail fed a purified diet containing 13.85% protein and 515 mg/kg of choline grew poorly. Growth was unaffected by additional choline in this diet. Growth was suboptimal among quail fed purified diets containing adequate or high (41.55%) levels of protein in which choline was limiting; however, a high level of protein did not in itself affect performance. Growth was improved by supplemental choline in these diets. Growth of quail fed purified diets with up to 1.35% excess methionine which were limiting (531 mg/kg) in choline was less than that of groups fed 2000 mg/kg of added dietary choline (P less than .01); however, excess methionine did not significantly influence growth of quail fed choline-deficient diets. These experiments indicate that neither high dietary protein nor excess methionine, fed at non-growth-depressing levels, increases dietary choline needs for young Bobwhite quail.
Sequence of the amino-terminal region of rat liver ribosomal proteins S4, S6, S8, L6, L7a, L18, L27, L30, L37, L37a, and L39.

Science.gov (United States)

Wittmann-Liebold, B; Geissler, A W; Lin, A; Wool, I G

1979-01-01

The sequence of the amino-terminal region of eleven rat liver ribosomal proteins--S4, S6, S8, L6, L7a, L18, L27, L30, L37a, and L39--was determined. The analysis confirmed the homogeneity of the proteins and suggests that they are unique, since no extensive common sequences were found. The N-terminal regions of the rat liver proteins were compared with amino acid sequences in Saccharomyces cerevisiae and in Escherichia coli ribosomal proteins. It seems likely that the proteins L37 from rat liver and Y55 from yeast ribosomes are homologous. It is possible that rat liver L7a or L37a or both are related to S cerevisiae Y44, although the similar sequences are at the amino-terminus of the rat liver proteins and in an internal region of Y44. A number of similarities in the sequences of rat liver and E coli ribosomal proteins have been found; however, it is not yet possible to say whether they connote a common ancestry.
Seleno methionine-75 as a scanning agent for neuroblastoma

International Nuclear Information System (INIS)

Covington, E.E.; D'Angio, G.J.; Helson, L.; Romano, R.W.

1974-01-01

Neuroblastoma is a functioning tumor and patients with this tumor are known to excrete vanilmandelic acid and other degradation products of norepinephrine. It also accumulates and produces excess cystathionine for which methionine is a precursor in the normal anabolic pathway. This was the rationale for testing 75 Se-methionine as a possible scanning agent in patients with neuroblastoma. D'Angio et al reported the results of a preliminary investigation in which 3 of 4 patients with neuroblastoma, all with known metastases of the skull, had positive scans correctly localizing the disease. These preliminary data seemed encouraging, and further investigation was undertaken. The results are reported
Methionine-supplemented diet affects the expression of cardiovascular disease-related genes and increases inflammatory cytokines in mice heart and liver.

Science.gov (United States)

Aissa, Alexandre Ferro; Amaral, Catia Lira do; Venancio, Vinicius Paula; Machado, Carla da Silva; Hernandes, Lívia Cristina; Santos, Patrick Wellington da Silva; Curi, Rui; Bianchi, Maria de Lourdes Pires; Antunes, Lusânia Maria Greggi

2017-01-01

Some important environmental factors that influence the development of cardiovascular diseases (CVD) include tobacco, excess alcohol, and unhealthy diet. Methionine obtained from the diet participates in the synthesis of DNA, proteins, lipids and affects homocysteine levels, which is associated with the elevated risk for CVD development. Therefore, the aim of this study was to investigate the manner in which dietary methionine might affect cellular mechanisms underlying CVD occurrence. Swiss albino mice were fed either control (0.3% DL-methionine), methionine-supplemented (2% DL-methionine), or a methionine-deprived diet (0% DL-methionine) over a 10-week period. The parameters measured included plasma homocysteine concentrations, oxidative stress by reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, levels of inflammatory cytokines IL-1ß, TNF-α, and IL-6, as well as expression of genes associated with CVD. The levels of apolipoprotein A5 (APOA5), a regulator of plasma triglycerides, were measured. The methionine-supplemented diet increased oxidative stress by lowering the GSH/GSSG ratio in heart tissues and decreased expression of the genes Apob, Ctgf, Serpinb2, Spp1, Il1b, and Sell, but elevated expression of Thbs4, Tgfb2, Ccr1, and Vegfa. Methionine-deprived diet reduced expression of Col3a1, Cdh5, Fabp3, Bax, and Hbegf and increased expression of Sell, Ccl5, Itga2, Birc3, Msr1, Bcl2a1a, Il1r2, and Selp. Methionine-deprived diet exerted pro-inflammatory consequences as evidenced by elevated levels of cytokines IL-1ß, TNF-α, and IL-6 noted in liver. Methionine-supplemented diet increased hepatic IL-6 and cardiac TNF-α. Both methionine supplementation and deprivation lowered hepatic levels of APOA5. In conclusion, data demonstrated that a methionine-supplemented diet modulated important biological processes associated with high risk of CVD development.
Investigation of the metal binding site in methionine aminopeptidase by density functional theory

DEFF Research Database (Denmark)

Jørgensen, Anne Techau; Norrby, Per-Ola; Liljefors, Tommy

2002-01-01

All methionine aminopeptidases exhibit the same conserved metal binding site. The structure of this site with either Co2+ ions or Zn2+ ions was investigated using density functional theory. The calculations showed that the structure of the site was not influenced by the identity of the metal ions....... This was the case for both of the systems studied; one based on the X-ray structure of the human methionine aminopeptidase type 2 (hMetAP-2) and the other based on the X-ray structure of the E. coli methionine aminopeptidase type 1 (eMetAP-1). Another important structural issue is the identity of the bridging...
Histone methyltransferases in cancer

DEFF Research Database (Denmark)

Albert, Mareike; Helin, Kristian

2009-01-01

Cancer is perceived as a heterogeneous group of diseases that is characterized by aberrant patterns of gene expression. In the last decade, an increasing amount of data has pointed to a key role for epigenetic alterations in human cancer. In this review, we focus on a subclass of epigenetic...... regulators, namely histone methyltransferases (HMTs). Several HMTs have been linked to different types of cancer; however, in most cases we only have limited knowledge regarding the molecular mechanisms by which the HMTs contribute to disease development. We summarize the current knowledge regarding some...
Association of a multi-synthetase complex with translating ribosomes in the archaeon Thermococcus kodakarensis

DEFF Research Database (Denmark)

Raina, Medha; Elgamal, Sara; Santangelo, Thomas J

2012-01-01

-dependent methyltransferase 144, GTP cyclohydrolase 398, DNA topoisomerase VI subunit A 209, DNA topoisomerase VI subunit B 192, Type A Flavoprotein 911, NAD(P)H:rubredoxin oxidoreductase (Fatty acid metabolism) 120, NAD(P)H:rubredoxin oxidoreductase 120, cofactor-independent phosphoglycerate mutase 909, bis(5'-adenosyl...... subunit 2 255, glycerol kinase 257, phosphomannomutase-related protein 321, ribose-5-phosphate isomerase A 107, phosphate transport regulator 193, isopentenyl pyrophosphate isomerase (mevanolate Pathway) 500, amino acid kinase 203, NADH:polysulfide oxidoreductase 203, 5'-methylthioadenosine phosphorylase......, cysteine desulfurase 521, hydrogenase maturation protein HypF 235, iron-molybdenum cofactor-binding protein 192, ATPase 260, 4Fe-4S cluster-binding protein 254, phosphopyruvate hydratase 650, fructose-1,6-bisphosphatase 140, aspartate carbamoyltransferase catalytic subunit 158, Bipolar DNA helicase 448...
Methionine supplementation in the productive efficiency, carcass ...

African Journals Online (AJOL)

The effect of dietary methionine supplementation at varying levels on the productive efficiency, carcass characteristics and economics of growing indigenous turkey was investigated. Four Isocaloric and Isonitrogenous diets were formulated. The diets were supplemented with 0.00%, 0.05%, 0.10%, and 0.15% respectively.
Fluoresence quenching of riboflavin in aqueous solution by methionin and cystein

International Nuclear Information System (INIS)

Droessler, P.; Holzer, W.; Penzkofer, A.; Hegemann, P.

2003-01-01

The fluorescence quantum distributions, fluorescence quantum yields, and fluorescence lifetimes of riboflavin in methanol, DMSO, water, and aqueous solutions of the sulphur atom containing amino acids methionin and cystein have been determined. In methanol, DMSO, and water (pH=4-8) only dynamic fluorescence reduction due to intersystem crossing and internal conversion is observed. In aqueous methionin solutions of pH=5.25-9 a pH independent static and dynamic fluorescence quenching occurs probably due to riboflavin anion-methionin cation pair formation. In aqueous cystein solutions (pH range from 4.15 to 9) the fluorescence quenching increases with rising pH due to cystein thiolate formation. The cystein thiol form present at low pH does not react with neutral riboflavin. Cystein thiolate present at high pH seems to react with neutral riboflavin causing riboflavin deprotonation (anion formation) by cystein thiolate reduction to the cystein thiol form
Bio-efficacy comparison of herbal-methionine and DL-methionine based on performance and blood parameters of broiler chickens

Directory of Open Access Journals (Sweden)

Sheila Hadinia

2014-06-01

Full Text Available This study was conducted to compare the bio-efficacy of herbal methionine (H-Met relative to DL-methionine (DL-Met on 160 “Ross 308” broiler chickens. DL-Met and H-Met were added to the basal diet in eight experimental treatments with three and four concentrations respectively in starter, grower and finisher period. Blood parameters which were measured at 24 and 42 days of age consisted of: serum proteins (total protein, albumin and globulin, serum uric acid, serum fats (low density lipoprotein, high density lipoprotein, triglyceride and cholesterol and serum enzymes (alanine amino transaminase and aspartate amino transaminase. Completely randomized design, multi-exponential and multilinear regressions were used to determine bio-efficacy of H-Met in terms of performance and blood parameters of broilers. The results showed that supplemented methionine (Met sources had no significant effect on blood parameters at 24 day of age. At 42 day of age the amounts of globulin and serum high density lipoprotein (HDL increased with supplemented Met, (p < 0.05. Regression analysis revealed that H-Met was 55.00, 71.00, 78.00, 47.00, 58.00 and 73.00% as efficacious as DL-Met for body weight gain, feed intake, feed conversion ratio, albumin, globulin and high density lipoprotein criteria, respectively. The average of bio-efficacy of H-Met compared to DL-Met was 67.00% and 59.00% on average across performance criteria and blood criteria respectively and was 63.00% across these two criteria tested. The results of the present study indicated that H-Met can be administered as a new and a natural source of Met in poultry industry.

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