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Sample records for aspartic acid residues

  1. Critical aspartic acid residues in pseudouridine synthases.

    Science.gov (United States)

    Ramamurthy, V; Swann, S L; Paulson, J L; Spedaliere, C J; Mueller, E G

    1999-08-01

    The pseudouridine synthases catalyze the isomerization of uridine to pseudouridine at particular positions in certain RNA molecules. Genomic data base searches and sequence alignments using the first four identified pseudouridine synthases led Koonin (Koonin, E. V. (1996) Nucleic Acids Res. 24, 2411-2415) and, independently, Santi and co-workers (Gustafsson, C., Reid, R., Greene, P. J., and Santi, D. V. (1996) Nucleic Acids Res. 24, 3756-3762) to group this class of enzyme into four families, which display no statistically significant global sequence similarity to each other. Upon further scrutiny (Huang, H. L., Pookanjanatavip, M., Gu, X. G., and Santi, D. V. (1998) Biochemistry 37, 344-351), the Santi group discovered that a single aspartic acid residue is the only amino acid present in all of the aligned sequences; they then demonstrated that this aspartic acid residue is catalytically essential in one pseudouridine synthase. To test the functional significance of the sequence alignments in light of the global dissimilarity between the pseudouridine synthase families, we changed the aspartic acid residue in representatives of two additional families to both alanine and cysteine: the mutant enzymes are catalytically inactive but retain the ability to bind tRNA substrate. We have also verified that the mutant enzymes do not release uracil from the substrate at a rate significant relative to turnover by the wild-type pseudouridine synthases. Our results clearly show that the aligned aspartic acid residue is critical for the catalytic activity of pseudouridine synthases from two additional families of these enzymes, supporting the predictive power of the sequence alignments and suggesting that the sequence motif containing the aligned aspartic acid residue might be a prerequisite for pseudouridine synthase function.

  2. Aspartic acid

    Science.gov (United States)

    Aspartic acid is a nonessential amino acids . Amino acids are building blocks of proteins. "Nonessential" means that our ... this amino acid from the food we eat. Aspartic acid is also called asparaginic acid. Aspartic acid helps ...

  3. Intramolecular cyclization of aspartic acid residues assisted by three water molecules: a density functional theory study

    Science.gov (United States)

    Takahashi, Ohgi; Kirikoshi, Ryota

    2014-01-01

    Aspartic acid (Asp) residues in peptides and proteins (l-Asp) are known to undergo spontaneous nonenzymatic reactions to form l-β-Asp, d-Asp, and d-β-Asp residues. The formation of these abnormal Asp residues in proteins may affect their three-dimensional structures and hence their properties and functions. Indeed, the reactions have been thought to contribute to aging and pathologies. Most of the above reactions of the l-Asp residues proceed via a cyclic succinimide intermediate. In this paper, a novel three-water-assisted mechanism is proposed for cyclization of an Asp residue (forming a gem-diol precursor of the succinimide) by the B3LYP/6-31 + G(d,p) density functional theory calculations carried out for an Asp-containing model compound (Ace-Asp-Nme, where Ace = acetyl and Nme = NHCH3). The three water molecules act as catalysts by mediating ‘long-range’ proton transfers. In the proposed mechanism, the amide group on the C-terminal side of the Asp residue is first converted to the tautomeric iminol form (iminolization). Then, reorientation of a water molecule and a conformational change occur successively, followed by the nucleophilic attack of the iminol nitrogen on the carboxyl carbon of the Asp side chain to form the gem-diol species. A satisfactory agreement was obtained between the calculated and experimental energetics.

  4. Site-Specific Pyrolysis Induced Cleavage at Aspartic Acid Residue in Peptides and Proteins

    Science.gov (United States)

    Zhang, Shaofeng; Basile, Franco

    2011-01-01

    A simple and site-specific non-enzymatic method based on pyrolysis has been developed to cleave peptides and proteins. Pyrolytic cleavage was found to be specific and rapid as it induced a cleavage at the C-terminal side of aspartic acid in the temperature range of 220–250 °C in 10 seconds. Electrospray Ionization (ESI) mass spectrometry (MS) and tandem-MS (MS/MS) were used to characterize and identify pyrolysis cleavage products, confirming that sequence information is conserved after the pyrolysis process in both peptides and protein tested. This suggests that pyrolysis-induced cleavage at aspartyl residues can be used as a rapid protein digestion procedure for the generation of sequence specific protein biomarkers. PMID:17388620

  5. Mutation in aspartic acid residues modifies catalytic and haemolytic activities of Bacillus cereus sphingomyelinase.

    Science.gov (United States)

    Tamura, H; Tameishi, K; Yamada, A; Tomita, M; Matsuo, Y; Nishikawa, K; Ikezawa, H

    1995-01-01

    Four aspartic acid residues (Asp126, Asp156, Asp233 and Asp295) of Bacillus cereus sphingomyelinase (SMase) in the conservative regions were changed to glycine by in vitro mutagenesis, and the mutant SMases [D126G (Asp126-->Gly etc.), D156G, D233G and D295G] were produced in Bacillus brevis 47, a protein-producing strain. The sphingomyelin (SM)-hydrolysing activity of D295G was completely abolished and those of D126G and D156G were reduced by more than 80%, whereas that of D233G was not so profoundly affected. Two mutant enzymes (D126G and D156G) were purified and characterized further. The hydrolytic activities of D126G and D156G toward four phosphocholine-containing substrates with different hydrophobicities, SM, 2-hexadecanoylamino-4-nitrophenylphosphocholine(HNP), lysophosphatidylcholine (lysoPC) and p-nitro-phenylphosphocholine (p-NPPC), were compared with those of the wild-type. The activity of D126G toward water-soluble p-NPPC was comparable with that of the wild-type. On the other hand, D156G catalysed the hydrolysis of hydrophilic substrates such as HNP and p-NPPC more efficiently (> 4-fold) than the wild-type. These results suggested that Asp126 and Asp156, located in the highly conserved region, may well be involved in a substrate recognition process rather than catalytic action. Haemolytic activities of the mutant enzymes were found to be parallel with their SM-hydrolysing activities. Two regions, including the C-terminal region containing Asp295, were found to show considerable sequence identity with the corresponding regions of bovine pancreatic DNase I. Structural predictions indicated structural similarity between SMase and DNase I. An evolutionary relationship based on the catalytic function was suggested between the structures of these two phosphodiesterases. Images Figure 2 Figure 3 Figure 4 Figure 6 PMID:7639690

  6. Acetic Acid Can Catalyze Succinimide Formation from Aspartic Acid Residues by a Concerted Bond Reorganization Mechanism: A Computational Study

    Science.gov (United States)

    Takahashi, Ohgi; Kirikoshi, Ryota; Manabe, Noriyoshi

    2015-01-01

    Succinimide formation from aspartic acid (Asp) residues is a concern in the formulation of protein drugs. Based on density functional theory calculations using Ace-Asp-Nme (Ace = acetyl, Nme = NHMe) as a model compound, we propose the possibility that acetic acid (AA), which is often used in protein drug formulation for mildly acidic buffer solutions, catalyzes the succinimide formation from Asp residues by acting as a proton-transfer mediator. The proposed mechanism comprises two steps: cyclization (intramolecular addition) to form a gem-diol tetrahedral intermediate and dehydration of the intermediate. Both steps are catalyzed by an AA molecule, and the first step was predicted to be rate-determining. The cyclization results from a bond formation between the amide nitrogen on the C-terminal side and the side-chain carboxyl carbon, which is part of an extensive bond reorganization (formation and breaking of single bonds and the interchange of single and double bonds) occurring concertedly in a cyclic structure formed by the amide NH bond, the AA molecule and the side-chain C=O group and involving a double proton transfer. The second step also involves an AA-mediated bond reorganization. Carboxylic acids other than AA are also expected to catalyze the succinimide formation by a similar mechanism. PMID:25588215

  7. Acetic Acid Can Catalyze Succinimide Formation from Aspartic Acid Residues by a Concerted Bond Reorganization Mechanism: A Computational Study

    Directory of Open Access Journals (Sweden)

    Ohgi Takahashi

    2015-01-01

    Full Text Available Succinimide formation from aspartic acid (Asp residues is a concern in the formulation of protein drugs. Based on density functional theory calculations using Ace-Asp-Nme (Ace = acetyl, Nme = NHMe as a model compound, we propose the possibility that acetic acid (AA, which is often used in protein drug formulation for mildly acidic buffer solutions, catalyzes the succinimide formation from Asp residues by acting as a proton-transfer mediator. The proposed mechanism comprises two steps: cyclization (intramolecular addition to form a gem-diol tetrahedral intermediate and dehydration of the intermediate. Both steps are catalyzed by an AA molecule, and the first step was predicted to be rate-determining. The cyclization results from a bond formation between the amide nitrogen on the C-terminal side and the side-chain carboxyl carbon, which is part of an extensive bond reorganization (formation and breaking of single bonds and the interchange of single and double bonds occurring concertedly in a cyclic structure formed by the amide NH bond, the AA molecule and the side-chain C=O group and involving a double proton transfer. The second step also involves an AA-mediated bond reorganization. Carboxylic acids other than AA are also expected to catalyze the succinimide formation by a similar mechanism.

  8. The highly conserved aspartic acid residue between hypervariable regions 1 and 2 of human immunodeficiency virus type 1 gp120 is important for early stages of virus replication.

    Science.gov (United States)

    Wang, W K; Essex, M; Lee, T H

    1995-01-01

    Between hypervariable regions V1 and V2 of human immunodeficiency virus type 1 (HIV-1) gp120 lies a cluster of relatively conserved residues. The contribution of nine charged residues in this region to virus infectivity was evaluated by single-amino-acid substitutions in an infectious provirus clone. Three of the HIV-1 mutants studied had slower growth kinetics than the wild-type virus. The delay was most pronounced in a mutant with an alanine substituted for an aspartic acid residue at position 180. This aspartic acid is conserved by all HIV-1 isolates with known nucleotide sequences. Substitutions with three other residues at this position, including a negatively charged glutamic acid, all affected virus infectivity. The defect identified in these mutants suggests that this aspartic acid residue is involved in the early stages of HIV-1 replication. PMID:7983752

  9. Phospho-N-Acetyl-Muramyl-Pentapeptide Translocase from Escherichia coli: Catalytic Role of Conserved Aspartic Acid Residues

    Science.gov (United States)

    Lloyd, Adrian J.; Brandish, Philip E.; Gilbey, Andrea M.; Bugg, Timothy D. H.

    2004-01-01

    Phospho-N-acetyl-muramyl-pentapeptide translocase (translocase 1) catalyzes the first of a sequence of lipid-linked steps that ultimately assemble the peptidoglycan layer of the bacterial cell wall. This essential enzyme is the target of several natural product antibiotics and has recently been the focus of antimicrobial drug discovery programs. The catalytic mechanism of translocase 1 is believed to proceed via a covalent intermediate formed between phospho-N-acetyl-muramyl-pentapeptide and a nucleophilic amino acid residue. Amino acid sequence alignments of the translocase 1 family and members of the related transmembrane phosphosugar transferase superfamily revealed only three conserved residues that possess nucleophilic side chains: the aspartic acid residues D115, D116, and D267. Here we report the expression and partial purification of Escherichia coli translocase 1 as a C-terminal hexahistidine (C-His6) fusion protein. Three enzymes with the site-directed mutations D115N, D116N, and D267N were constructed, expressed, and purified as C-His6 fusions. Enzymatic analysis established that all three mutations eliminated translocase 1 activity, and this finding verified the essential role of these residues. By analogy with the structural environment of the double aspartate motif found in prenyl transferases, we propose a model whereby D115 and D116 chelate a magnesium ion that coordinates with the pyrophosphate bridge of the UDP-N-acetyl-muramyl-pentapeptide substrate and in which D267 therefore fulfills the role of the translocase 1 active-site nucleophile. PMID:14996806

  10. A highly Conserved Aspartic Acid Residue of the Chitosanase from Bacillus Sp. TS Is Involved in the Substrate Binding.

    Science.gov (United States)

    Zhou, Zhanping; Zhao, Shuangzhi; Liu, Yang; Chang, Zhengying; Ma, Yanhe; Li, Jian; Song, Jiangning

    2016-11-01

    The chitosanase from Bacillus sp. TS (CsnTS) is an enzyme belonging to the glycoside hydrolase family 8. The sequence of CsnTS shares 98 % identity with the chitosanase from Bacillus sp. K17. Crystallography analysis and site-direct mutagenesis of the chitosanase from Bacillus sp. K17 identified the important residues involved in the catalytic interaction and substrate binding. However, despite progress in understanding the catalytic mechanism of the chitosanase from the family GH8, the functional roles of some residues that are highly conserved throughout this family have not been fully elucidated. This study focused on one of these residues, i.e., the aspartic acid residue at position 318. We found that apart from asparagine, mutation of Asp318 resulted in significant loss of enzyme activity. In-depth investigations showed that mutation of this residue not only impaired enzymatic activity but also affected substrate binding. Taken together, our results showed that Asp318 plays an important role in CsnTS activity.

  11. Aspartic Acid Residue D3 Critically Determines Cx50 Gap Junction Channel Transjunctional Voltage-Dependent Gating and Unitary Conductance

    Science.gov (United States)

    Xin, Li; Nakagawa, So; Tsukihara, Tomitake; Bai, Donglin

    2012-01-01

    Previous studies have suggested that the aspartic acid residue (D) at the third position is critical in determining the voltage polarity of fast Vj-gating of Cx50 channels. To test whether another negatively charged residue (a glutamic acid residue, E) could fulfill the role of the D3 residue, we generated the mutant Cx50D3E. Vj-dependent gating properties of this mutant channel were characterized by double-patch-clamp recordings in N2A cells. Macroscopically, the D3E substitution reduced the residual conductance (Gmin) to near zero and outwardly shifted the half-inactivation voltage (V0), which is a result of both a reduced aggregate gating charge (z) and a reduced free-energy difference between the open and closed states. Single Cx50D3E gap junction channels showed reduced unitary conductance (γj) of the main open state, reduced open dwell time at ±40 mV, and absence of a long-lived substate. In contrast, a G8E substitution tested to compare the effects of the E residue at the third and eighth positions did not modify the Vj-dependent gating profile or γj. In summary, this study is the first that we know of to suggest that the D3 residue plays an essential role, in addition to serving as a negative-charge provider, as a critical determinant of the Vj-dependent gating sensitivity, open-closed stability, and unitary conductance of Cx50 gap junction channels. PMID:22404924

  12. Mutation of aspartic acid residues in the fructosyltransferase of Streptococcus salivarius ATCC 25975.

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    Song, D D; Jacques, N A

    1999-01-01

    The site-directed mutated fructosyltransferases (Ftfs) of Streptococcus salivarius ATCC 25975, D312E, D312S, D312N and D312K were all active at 37 degrees C, indicating that Asp-312 present in the 'sucrose box' was not the nucleophilic Asp residue responsible for the formation of a covalent fructosyl-enzyme intermediate required for enzyme activity. Analysis of the kinetic constants of the purified mutated forms of the enzyme showed that Asp-312 was most likely an essential amino acid involved in determining acceptor recognition and/or stabilizing a beta-turn in the protein. In contrast, when the Asp-397 of the Ftf present in the conserved triplet RDP motif of all 60 bacterial and plant family-32 glycosylhydrolases was mutated to a Ser residue, both sucrose hydrolysis and polymerization ceased. Tryptophan emission spectra confirmed that this mutation did not alter protein structure. Comparison of published data from other site-directed mutated enzymes implicated the Asp residue in the RDP motif as the one that may form a transient covalent fructosyl intermediate during the catalysis of sucrose by the Ftf of S. salivarius. PMID:10548559

  13. Factors contributing to decreased protein stability when aspartic acid residues are in {beta}-sheet regions.

    Energy Technology Data Exchange (ETDEWEB)

    Pokkuluri, P. R.; Cai, X.; Raffen, R.; Gu, M.; Stevens, F. J.; Schiffer, M.

    2002-07-01

    Asp residues are significantly under represented in {beta}-sheet regions of proteins, especially in the middle of {beta}-strands, as found by a number of studies using statistical, modeling, or experimental methods. To further understand the reasons for this under representation of Asp, we prepared and analyzed mutants of a {beta}-domain. Two Gln residues of the immunoglobulin light-chain variable domain (V{sub L}) of protein Len were replaced with Asp, and then the effects of these changes on protein stability and protein structure were studied. The replacement of Q38D, located at the end of a {beta}-strand, and that of Q89D, located in the middle of a {beta}-strand, reduced the stability of the parent immunoglobulin VL domain by 2.0 kcal/mol and 5.3 kcal/mol, respectively. Because the Q89D mutant of the wild-type V{sub L}-Len domain was too unstable to be expressed as a soluble protein, we prepared the Q89D mutant in a triple mutant background, V{sub L}-Len M4L/Y27dD/T94H, which was 4.2 kcal/mol more stable than the wild-type V{sub L}-Len domain. The structures of mutants V{sub L}-Len Q38D and V{sub L}-Len Q89D/M4L/Y27dD/T94H were determined by X-ray diffraction at 1.6 A resolution. We found no major perturbances in the structures of these QD mutant proteins relative to structures of the parent proteins. The observed stability changes have to be accounted for by cumulative effects of the following several factors: (1) by changes in main-chain dihedral angles and in side-chain rotomers, (2) by close contacts between some atoms, and, most significantly, (3) by the unfavorable electrostatic interactions between the Asp side chain and the carbonyls of the main chain. We show that the Asn side chain, which is of similar size but neutral, is less destabilizing. The detrimental effect of Asp within a {beta}-sheet of an immunoglobulin-type domain can have very serious consequences. A somatic mutation of a {beta}-strand residue to Asp could prevent the expression of the

  14. Triazacyclophane (TAC)-scaffolded histidine and aspartic acid residues as mimics of non-heme metalloenzyme active sites

    NARCIS (Netherlands)

    Albada, H.B.; Soulimani, F.; Jacobs, H.J.F.; Versluis, C.; Weckhuysen, B.M.; Liskamp, R.M.J.

    2012-01-01

    We describe the synthesis and coordination behaviour to copper(II) of two close structural triazacyclophane-based mimics of two often encountered aspartic acid and histidine containing metalloenzyme active sites. Coordination of these mimics to copper(I) and their reaction with molecular oxygen lead

  15. The role of aspartic acid residues 405 and 416 of the kidney isotype of sodium-bicarbonate cotransporter 1 in its targeting to the plasma membrane

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    Kucher, Volodymyr; Li, Emily Y.; Conforti, Laura; Zahedi, Kamyar A.

    2012-01-01

    The NH2 terminus of the sodium-bicarbonate cotransporter 1 (NBCe1) plays an important role in its targeting to the plasma membrane. To identify the amino acid residues that contribute to the targeting of NBCe1 to the plasma membrane, polarized MDCK cells were transfected with expression constructs coding for green fluorescent protein (GFP)-tagged NBCe1 NH2-terminal deletion mutants, and the localization of GFP-tagged proteins was analyzed by confocal microscopy. Our results indicate that the amino acids between residues 399 and 424 of NBCe1A contain important sequences that contribute to its localization to the plasma membrane. Site-directed mutagenesis studies showed that GFP-NBCe1A mutants D405A and D416A are retained in the cytoplasm of the polarized MDCK epithelial cells. Examination of functional activities of D405A and D416A reveals that their activities are reduced compared with the wild-type NBCe1A. Similarly, aspartic acid residues 449 and 460 of pancreatic NBCe1 (NBCe1B), which correspond to residues 405 and 416 of NBCe1A, are also required for its full functional activity and accurate targeting to the plasma membrane. In addition, while replacement of D416 with glutamic acid did not affect the targeting or functional activity of NBCe1A, substitution of D405 with glutamic acid led to the retention of the mutated protein in the intracellular compartment and impaired functional activity. These studies demonstrate that aspartic acid residues 405 and 416 in the NH2 terminus of NBCe1A are important in its accurate targeting to the plasma membrane. PMID:22442137

  16. Role of four conserved aspartic acid residues of EF-loops in the metal ion binding and in the self-assembly of ciliate Euplotes octocarinatus centrin.

    Science.gov (United States)

    Liu, Wen; Duan, Lian; Sun, Tijian; Yang, Binsheng

    2016-12-01

    Ciliate Euplotes octocarinatus centrin (EoCen) is an EF-hand calcium-binding protein closely related to the prototypical calcium sensor protein calmodulin. Four mutants (D37K, D73K, D110K and D146K) were created firstly to elucidate the importance of the first aspartic acid residues (Asp37, Asp73, Asp110 and Asp146) in the beginning of the four EF-loops of EoCen. Aromatic-sensitized Tb(3+) fluorescence indicates that the aspartic acid residues are very important for the metal-binding of EoCen, except for Asp73 (in EF-loop II). Resonance light scattering (RLS) measurements for different metal ions (Ca(2+) and Tb(3+)) binding proteins suggest that the order of four conserved aspartic acid residues for contributing to the self-assembly of EoCen is Asp37 > Asp146 > Asp110 > Asp73. Cross-linking experiment also exhibits that Asp37 and Asp146 play critical role in the self-assembly of EoCen. Asp37, in site I, which is located in the N-terminal domain, plays the most important role in the metal ion-dependent self-assembly of EoCen, and there is cooperativity between N-terminal and C-terminal domain (especially the site IV). In addition, the dependence of Tb(3+) induced self-assembly of EoCen and the mutants on various factors, including ionic strength and pH, were characterized using RLS. Finally, 2-p-toluidinylnaphthalene-6-sulfonate (TNS) binding, ionic strength and pH control experiments indicate that in the process of EoCen self-assembly, molecular interactions are mediated by both electrostatic and hydrophobic forces, and the hydrophobic interaction has the important status.

  17. Just three water molecules can trigger the undesired nonenzymatic reactions of aspartic acid residues: new insight from a quantum-chemical study

    Science.gov (United States)

    Takahashi, O.

    2014-03-01

    Aspartic acid (Asp) residues in peptides and proteins (L-Asp) can undergo spontaneous, nonenzymatic reactions under physiological conditions by which abnormal L-β-Asp, D-Asp, and/or D-β-Asp residues are formed. These altered Asp residues may affect the three-dimensional structures of the peptides and proteins and hence their properties and functions. In fact, the altered Asp residues are relevant to age-related diseases such as cataract and Alzheimer's disease. Most of the above reactions of the L-Asp residue proceed via a cyclic succinimide intermediate. In this paper, I propose a detailed mechanism of cyclization of an Asp residue (forming a precursor of the succinimide) by the B3LYP/6-31+G(d,p) density functional theory calculations carried out for a small Asp-containing model compound complexed with three water molecules which act as general acid-base catalysts in proton transfers. In the proposed mechanism, the amide group on the C-terminal side of the Asp residue is first converted to the tautomeric iminol form. Then, successive reorientation of a water molecule and conformational change occur followed by the nucleophilic attack of the iminol nitrogen atom on the carboxyl carbon atom of the Asp side chain to form a five-membered ring. A satisfactory agreement was obtained between the calculated and experimental energetics.

  18. Identification of two conserved aspartic acid residues required for DNA digestion by a novel thermophilic Exonuclease VII in Thermotoga maritima

    Science.gov (United States)

    Larrea, Andres A.; Pedroso, Ilene M.; Malhotra, Arun; Myers, Richard S.

    2008-01-01

    Exonuclease VII was first identified in 1974 as a DNA exonuclease that did not require any divalent cations for activity. Indeed, Escherichia coli ExoVII was identified in partially purified extracts in the presence of EDTA. ExoVII is comprised of two subunits (XseA and XseB) that are highly conserved and present in most sequenced prokaryotic genomes, but are not seen in eukaryotes. To better understand this exonuclease family, we have characterized an ExoVII homolog from Thermotoga maritima. Thermotoga maritima XseA/B homologs TM1768 and TM1769 were co-expressed and purified, and show robust nuclease activity at 80°C. This activity is magnesium dependent and is inhibited by phosphate ions, which distinguish it from E. coli ExoVII. Nevertheless, both E. coli and T. maritima ExoVII share a similar putative active site motif with two conserved aspartate residues in the large (XseA/TM1768) subunit. We show that these residues, Asp235 and Asp240, are essential for the nuclease activity of T. maritima ExoVII. We hypothesize that the ExoVII family of nucleases can be sub-divided into two sub-families based on EDTA resistance and that T. maritima ExoVII is the first member of the branch that is characterized by EDTA sensitivity and inhibition by phosphate. PMID:18812402

  19. A replacement of the active-site aspartic acid residue 293 in mouse cathepsin D affects its intracellular stability, processing and transport in HEK-293 cells.

    Science.gov (United States)

    Partanen, Sanna; Storch, Stephan; Löffler, Hans-Gerhard; Hasilik, Andrej; Tyynelä, Jaana; Braulke, Thomas

    2003-01-01

    The substitution of an active-site aspartic acid residue by asparagine in the lysosomal protease cathepsin D (CTSD) results in a loss of enzyme activity and severe cerebrocortical atrophy in a novel form of neuronal ceroid lipofuscinosis in sheep [Tyynelä, Sohar, Sleat, Gin, Donnelly, Baumann, Haltia and Lobel (2000) EMBO J. 19, 2786-2792]. In the present study we have introduced the corresponding mutation by replacing aspartic acid residue 293 with asparagine (D293N) into the mouse CTSD cDNA to analyse its effect on synthesis, transport and stability in transfected HEK-293 cells. The complete inactivation of mutant D293N mouse CTSD was confirmed by a newly developed fluorimetric quantification system. Moreover, in the heterologous overexpression systems used, mutant D293N mouse CTSD was apparently unstable and proteolytically modified during early steps of the secretory pathway, resulting in a loss of mass by about 1 kDa. In the affected sheep, the endogenous mutant enzyme was stable but also showed the shift in its molecular mass. In HEK-293 cells, the transport of the mutant D293N mouse CTSD to the lysosome was delayed and associated with a low secretion rate compared with wild-type CTSD. These data suggest that the mutation may result in a conformational change which affects stability, processing and transport of the enzyme. PMID:12350228

  20. Roles of Intramolecular and Intermolecular Hydrogen Bonding in a Three-Water-Assisted Mechanism of Succinimide Formation from Aspartic Acid Residues

    Directory of Open Access Journals (Sweden)

    Ohgi Takahashi

    2014-08-01

    Full Text Available Aspartic acid (Asp residues in peptides and proteins are prone to isomerization to the β-form and racemization via a five-membered succinimide intermediate. These nonenzymatic reactions have relevance to aging and age-related diseases. In this paper, we report a three water molecule-assisted, six-step mechanism for the formation of succinimide from Asp residues found by density functional theory calculations. The first two steps constitute a stepwise iminolization of the C-terminal amide group. This iminolization involves a quintuple proton transfer along intramolecular and intermolecular hydrogen bonds formed by the C-terminal amide group, the side-chain carboxyl group, and the three water molecules. After a conformational change (which breaks the intramolecular hydrogen bond involving the iminol nitrogen and a reorganization of water molecules, the iminol nitrogen nucleophilically attacks the carboxyl carbon of the Asp side chain to form a five-membered ring. This cyclization is accompanied by a triple proton transfer involving two water molecules, so that a gem-diol tetrahedral intermediate is formed. The last step is dehydration of the gem-diol group catalyzed by one water molecule, and this is the rate-determining step. The calculated overall activation barrier (26.7 kcal mol−1 agrees well with an experimental activation energy.

  1. Histidine and Aspartic Acid Residues Important for Immunoglobulin G Endopeptidase Activity of the Group A Streptococcus Opsonophagocytosis-Inhibiting Mac Protein

    Science.gov (United States)

    Lei, Benfang; Liu, Mengyao; Meyers, Elishia G.; Manning, Heather M.; Nagiec, Michael J.; Musser, James M.

    2003-01-01

    The secreted Mac protein made by serotype M1 group A Streptococcus (GAS) (designated Mac5005) inhibits opsonophagocytosis and killing of GAS by human polymorphonuclear neutrophils. This protein also has cysteine endopeptidase activity against human immunoglobulin G (IgG). Site-directed mutagenesis was used to identify histidine and aspartic acid residues important for Mac IgG endopeptidase activity. Replacement of His262 with Ala abolished Mac5005 IgG endopeptidase activity. Asp284Ala and Asp286Ala mutant proteins had compromised enzymatic activity, whereas 21 other Asp-to-Ala mutant proteins cleaved human IgG at the apparent wild-type level. The results suggest that His262 is an active-site residue and that Asp284 and Asp286 are important for the enzymatic activity or structure of Mac protein. These Mac mutants provide new information about structure-activity relationships in this protein and will assist study of the mechanism of inhibition of opsonophagocytosis and killing of GAS by Mac. PMID:12704162

  2. Chemical modification of Penicillium 1,2-alpha-D-mannosidase by water-soluble carbodi-imide: identification of a catalytically important aspartic acid residue.

    Science.gov (United States)

    Yoshida, T; Maeda, K; Kobayashi, M; Ichishima, E

    1994-01-01

    1,2-alpha-D-Mannosidase from Penicillium citrinum was inactivated by chemical modification with 1-ethyl-3-(3-dimethylamino-propyl)carbodi-imide (EDC). Most of the activity was lost after modification in the absence of a nucleophile, glycine ethyl ester. 1-Deoxymannojirimycin (dMM), a competitive inhibitor of the enzyme, showed partial protection against the inactivation. After the modification by EDC without the presence of a nucleophile, proteolytic digests of the enzyme were analysed by reversed-phase h.p.l.c. and a unique peptide was shown to decrease when dMM was present during the modification. The peptide was absent from the digests of unmodified enzyme. The amino acid sequence of the peptide (A; Ile-Gly-Pro) was identical in part with that of the adjacent peptide (B; Ile-Gly-Pro-Asp-Ser-Trp-Gly-Trp-Asp-Pro-Lys). When cholecystokinin tetrapeptide (Trp-Met-Asp-Phe-NH2) was modified by EDC alone, the modified peptide could be separated from unmodified peptide by reversed-phase h.p.i.c., and Edman degradation was stopped before the modified aspartic acid residue. This suggested that, in the enzyme, peptide A was derived from peptide B by the modification. Consequently, Asp-4 in peptide B was assumed to be masked by dMM during the modification, and to be involved in the interaction of the enzyme with its substrate. PMID:7945271

  3. 21 CFR 582.5017 - Aspartic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aspartic acid. 582.5017 Section 582.5017 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5017 Aspartic acid. (a)...

  4. MD-2 Residues Tyrosine 42, Arginine 69, Aspartic Acid 122, and Leucine 125 Provide Species Specificity for Lipid IVA*

    Science.gov (United States)

    Meng, Jianmin; Drolet, Joshua R.; Monks, Brian G.; Golenbock, Douglas T.

    2010-01-01

    Lipopolysaccharide (LPS) activates the innate immune response through the Toll-like receptor 4 (TLR4)·MD-2 complex. A synthetic lipid A precursor, lipid IVA, induces an innate immune response in mice but not in humans. Both TLR4 and MD-2 are required for the agonist activity of lipid IVA in mice, with TLR4 interacting through specific surface charges at the dimerization interface. In this study, we used site-directed mutagenesis to identify the MD-2 residues that determine lipid IVA species specificity. A single mutation of murine MD-2 at the hydrophobic pocket entrance, E122K, substantially reduced the response to lipid IVA. Combining the murine MD-2 E122K with the murine TLR4 K367E/S386K/R434Q mutations completely abolished the response to lipid IVA, effectively converting the murine cellular response to a human-like response. In human cells, however, simultaneous mutations of K122E, K125L, Y41F, and R69G on human MD-2 were required to promote a response to lipid IVA. Combining the human MD-2 quadruple mutations with the human TLR4 E369K/Q436R mutations completely converted the human MD-2/human TLR4 receptor to a murine-like receptor. Because MD-2 residues 122 and 125 reside at the dimerization interface near the pocket entrance, surface charge differences here directly affect receptor dimerization. In comparison, residues 42 and 69 reside at the MD-2/TLR4 interaction surface opposite the dimerization interface. Surface charge differences there likely affect the binding angle and/or rigidity between MD-2 and TLR4, exerting an indirect influence on receptor dimerization and activation. Thus, surface charge differences at the two MD-2/TLR4 interfaces determine the species-specific activation of lipid IVA. PMID:20592019

  5. The hydrothermal reaction kinetics of aspartic acid

    Science.gov (United States)

    Cox, Jenny S.; Seward, Terry M.

    2007-02-01

    Experimental data on the hydrothermal reaction kinetics of aspartic acid were acquired using a custom-built spectrophotometric reaction cell which permits in situ observation under hydrothermal conditions. The results of this study indicate that the reaction kinetics of dilute aspartic acid solutions are significantly different depending on the presence or absence of catalytic surfaces such as standard metal alloys. The spectroscopic data presented here represent the first direct observations, in situ and in real time, of an amino acid reacting in a hydrothermal solution. Quantitative kinetic information, including rate constants, concentration versus time profiles, and calculations of the individual component spectra, was obtained from the data using a chemometric approach based on factor analysis/principle component analysis which treats the rate expressions simultaneously as a system of differential algebraic equations (DAE) of index 1. Identification of the products was confirmed where possible by high pressure anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The reaction kinetics of aspartic acid under hydrothermal conditions was observed to be highly complex, in contrast to previous studies which indicated almost exclusively deamination. At lower temperatures (120-170 °C), several different reaction pathways were observed, including decarboxylation and polymerization, and the catalytic effects of reactor surfaces on the aspartic acid system were clearly demonstrated. At higher temperatures (above 170 °C), aspartic acid exhibited highly complex behaviour, with evidence indicating that it can simultaneously dimerize and cyclize, deaminate (by up to two pathways), and decarboxylate (by up to two pathways). These higher temperature kinetics were not fully resolvable in a quantitative manner due to the complexity of the system and the constraints of UV spectroscopy. The results of this study provide strong evidence that the reaction

  6. Mutation of the aspartic acid residues of the GDD sequence motif of poliovirus RNA-dependent RNA polymerase results in enzymes with altered metal ion requirements for activity.

    Science.gov (United States)

    Jablonski, S A; Morrow, C D

    1995-01-01

    The poliovirus RNA-dependent RNA polymerase, 3Dpol, is known to share a region of sequence homology with all RNA polymerases centered at the GDD amino acid motif. The two aspartic acids have been postulated to be involved in the catalytic activity and metal ion coordination of the enzyme. To test this hypothesis, we have utilized oligonucleotide site-directed mutagenesis to generate defined mutations in the aspartic acids of the GDD motif of the 3Dpol gene. The codon for the first aspartate (3D-D-328 [D refers to the single amino acid change, and the number refers to its position in the polymerase]) was changed to that for glutamic acid, histidine, asparagine, or glutamine; the codons for both aspartic acids were simultaneously changed to those for glutamic acids; and the codon for the second aspartic acid (3D-D-329) was changed to that for glutamic acid or asparagine. The mutant enzymes were expressed in Escherichia coli, and the in vitro poly(U) polymerase activity was characterized. All of the mutant 3Dpol enzymes were enzymatically inactive in vitro when tested over a range of Mg2+ concentrations. However, when Mn2+ was substituted for Mg2+ in the in vitro assays, the mutant that substituted the second aspartic acid for asparagine (3D-N-329) was active. To further substantiate this finding, a series of different transition metal ions were substituted for Mg2+ in the poly(U) polymerase assay. The wild-type enzyme was active with all metals except Ca2+, while the 3D-N-329 mutant was active only when FeC6H7O5 was used in the reaction. To determine the effects of the mutations on poliovirus replication, the mutant 3Dpol genes were subcloned into an infectious cDNA of poliovirus. The cDNAs containing the mutant 3Dpol genes did not produce infectious virus when transfected into tissue culture cells under standard conditions. Because of the activity of the 3D-N-329 mutant in the presence of Fe2+ and Mn2+, transfections were also performed in the presence of the

  7. Cavity residue leucine 95 and channel residues glutamine 204, aspartic acid 211, and phenylalanine 269 of toluene o-xylene monooxygenase influence catalysis.

    Science.gov (United States)

    Kurt, Cansu; Sönmez, Burcu; Vardar, Nurcan; Yanık-Yıldırım, K Cansu; Vardar-Schara, Gönül

    2016-09-01

    Structural analysis of toluene-o-xylene monooxygenase (ToMO) hydroxylase revealed the presence of three hydrophobic cavities, a channel, and a pore leading from the protein surface to the active site. Here, saturation mutagenesis was used to investigate the catalytic roles of alpha-subunit (TouA) second cavity residue L95 and TouA channel residues Q204, D211, and F269. By testing the substrates toluene, phenol, nitrobenzene, and/or naphthalene, these positions were found to influence the catalytic activity of ToMO. Several regiospecific variants were identified from TouA positions Q204, F269, and L95. For example, TouA variant Q204H had the regiospecificity of nitrobenzene changed significantly from 30 to 61 % p-nitrophenol. Interestingly, a combination of mutations at Q204H and A106V altered the regiospecificity of nitrobenzene back to 27 % p-nitrophenol. TouA variants F269Y, F269P, Q204E, and L95D improved the meta-hydroxylating capability of nitrobenzene by producing 87, 85, 82, and 77 % m-nitrophenol, respectively. For naphthalene oxidation, TouA variants F269V, Q204A, Q204S/S222N, and F269T had the regiospecificity changed from 16 to 9, 10, 23, and 25 % 2-naphthol, respectively. Here, two additional TouA residues, S222 and A106, were also identified that may have important roles in catalysis. Most of the isolated variants from D211 remained active, whereas having a hydrophobic residue at this position appeared to diminish the catalytic activity toward naphthalene. The mutational effects on the ToMO regiospecificity described here suggest that it is possible to further fine tune and engineer the reactivity of multicomponent diiron monooxygenases toward different substrates at positions that are relatively distant from the active site.

  8. Identification of glutamic acid 204 and aspartic acid 200 in chitinase A1 of Bacillus circulans WL-12 as essential residues for chitinase activity.

    Science.gov (United States)

    Watanabe, T; Kobori, K; Miyashita, K; Fujii, T; Sakai, H; Uchida, M; Tanaka, H

    1993-09-01

    Prokaryotic chitinases, class III plant chitinases, yeast chitinases, and endo-beta-N-acetylglucosaminidases share weak amino acid sequence similarities at the certain region of each enzyme. These regions have been assumed to be important for catalytic activities of the enzymes. To verify this assumption, three amino acid residues (Ser-160, Asp-200, Glu-204) in chitinase A1 of Bacillus circulans WL-12 were chosen, based on the amino acid sequence alignment of the regions sharing sequence similarity, and were replaced by site-directed mutagenesis. Kinetic parameters for 4-methylumbelliferyl-N,N',N"-triacetylchitotriose hydrolysis were determined with wild-type and seven mutant chitinases. Chitinases with Glu-204-->Gln mutation and Glu-204-->Asp mutation were essentially inactive and kcat values of these chitinases were approximately 1/5,000 and 1/17,000 of that of wild-type chitinase, respectively. Asp-200-->Asn mutation decreased the kcat value to approximately 1/350 of that of the wild-type enzyme, while the Km value decreased only slightly. On the other hand, neither the kcat value nor the Km value was affected by Asp-200-->Glu mutation. Thus, it appeared that Glu-204 and Asp-200 are directly involved in the catalytic events of chitinase A1. The role of the carboxyl group of Asp-200 can be fully substituted by that of Glu residue. The Ser-160-->Ala mutant retained 10% activity of the wild-type chitinase indicating that the hydroxyl group of Ser-160 is not absolutely required for the catalytic activity. These results indicate a lysozyme-type catalytic mechanism of the chitinase.

  9. Prediction of binding modes between protein L-isoaspartyl (D-aspartyl) O-methyltransferase and peptide substrates including isomerized aspartic acid residues using in silico analytic methods for the substrate screening.

    Science.gov (United States)

    Oda, Akifumi; Noji, Ikuhiko; Fukuyoshi, Shuichi; Takahashi, Ohgi

    2015-12-10

    Because the aspartic acid (Asp) residues in proteins are occasionally isomerized in the human body, not only l-α-Asp but also l-β-Asp, D-α-Asp and D-β-Asp are found in human proteins. In these isomerized aspartic acids, the proportion of D-β-Asp is the largest and the proportions of l-β-Asp and D-α-Asp found in human proteins are comparatively small. To explain the proportions of aspartic acid isomers, the possibility of an enzyme able to repair l-β-Asp and D-α-Asp is frequently considered. The protein L-isoaspartyl (D-aspartyl) O-methyltransferase (PIMT) is considered one of the possible repair enzymes for l-β-Asp and D-α-Asp. Human PIMT is an enzyme that recognizes both l-β-Asp and D-α-Asp, and catalyzes the methylation of their side chains. In this study, the binding modes between PIMT and peptide substrates containing l-β-Asp or D-α-Asp residues were investigated using computational protein-ligand docking and molecular dynamics simulations. The results indicate that carboxyl groups of both l-β-Asp and D-α-Asp were recognized in similar modes by PIMT and that the C-terminal regions of substrate peptides were located in similar positions on PIMT for both the l-β-Asp and D-α-Asp peptides. In contrast, for peptides containing l-α-Asp or D-β-Asp residues, which are not substrates of PIMT, the computationally constructed binding modes between PIMT and peptides greatly differed from those between PIMT and substrates. In the nonsubstrate peptides, not inter- but intra-molecular hydrogen bonds were observed, and the conformations of peptides were more rigid than those of substrates. Thus, the in silico analytical methods were able to distinguish substrates from nonsubstrates and the computational methods are expected to complement experimental analytical methods.

  10. Crystal structure of putrescine aspartic acid complex

    OpenAIRE

    Ramaswamy, S.; Murthy, MRN

    1990-01-01

    Polyamines, putrescine, spermidine and spermine are ubiquitous biogenic cations believed to be important for a variety of cellular processes. In order to obtain structural information on the interaction of these amines with other biomolecules, the structure of a complex of putrescine with aspartic acid was determined using single crystal X-ray diffraction methods. The crystals belong monoclinic space group $C_2$ with $a = 21.504 \\AA$, $b = 4.779 \\AA$, $c = 8.350 \\AA$ and $\\beta = {97.63}^{\\ci...

  11. Age estimation based on aspartic acid racemization in human sclera.

    Science.gov (United States)

    Klumb, Karolin; Matzenauer, Christian; Reckert, Alexandra; Lehmann, Klaus; Ritz-Timme, Stefanie

    2016-01-01

    Age estimation based on racemization of aspartic acid residues (AAR) in permanent proteins has been established in forensic medicine for years. While dentine is the tissue of choice for this molecular method of age estimation, teeth are not always available which leads to the need to identify other suitable tissues. We examined the suitability of total tissue samples of human sclera for the estimation of age at death. Sixty-five samples of scleral tissue were analyzed. The samples were hydrolyzed and after derivatization, the extent of aspartic acid racemization was determined by gas chromatography. The degree of AAR increased with age. In samples from younger individuals, the correlation of age and D-aspartic acid content was closer than in samples from older individuals. The age-dependent racemization in total tissue samples proves that permanent or at least long-living proteins are present in scleral tissue. The correlation of AAR in human sclera and age at death is close enough to serve as basis for age estimation. However, the precision of age estimation by this method is lower than that of age estimation based on the analysis of dentine which is due to molecular inhomogeneities of total tissue samples of sclera. Nevertheless, the approach may serve as a valuable alternative or addition in exceptional cases.

  12. Aspartic acid substitutions affect proton translocation by bacteriorhodopsin.

    Science.gov (United States)

    Mogi, T; Stern, L J; Marti, T; Chao, B H; Khorana, H G

    1988-01-01

    We have substituted each of the aspartic acid residues in bacteriorhodopsin to determine their possible role in proton translocation by this protein. The aspartic acid residues were replaced by asparagines; in addition, Asp-85, -96, -115, and -112 were changed to glutamic acid and Asp-212 was also replaced by alanine. The mutant bacteriorhodopsin genes were expressed in Escherichia coli and the proteins were purified. The mutant proteins all regenerated bacteriorhodopsin-like chromophores when treated with a detergent-phospholipid mixture and retinal. However, the rates of regeneration of the chromophores and their lambda max varied widely. No support was obtained for the external point charge model for the opsin shift. The Asp-85----Asn mutant showed not detectable proton pumping, the Asp-96----Asn and Asp-212----Glu mutants showed less than 10% and the Asp-115----Glu mutant showed approximately equal to 30% of the normal proton pumping. The implications of these findings for possible mechanisms of proton translocation by bacteriorhodopsin are discussed. PMID:3288985

  13. Homoserine as an Aspartic Acid Precursor for Synthesis of Proteoglycan Glycopeptide Containing Aspartic Acid and a Sulfated Glycan Chain.

    Science.gov (United States)

    Yang, Weizhun; Ramadan, Sherif; Yang, Bo; Yoshida, Keisuke; Huang, Xuefei

    2016-12-02

    Among many hurdles in synthesizing proteoglycan glycopeptides, one challenge is the incorporation of aspartic acid in the peptide backbone and acid sensitive O-sulfated glycan chains. To overcome this, a new strategy was developed utilizing homoserine as an aspartic acid precursor. The conversion of homoserine to aspartic acid in the glycopeptide was successfully accomplished by late stage oxidation using (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (TEMPO) and bis(acetoxy)iodobenzene (BAIB). This is the first time that a glycopeptide containing aspartic acid and an O-sulfated glycan was synthesized.

  14. Non-enzymic beta-decarboxylation of aspartic acid.

    Science.gov (United States)

    Doctor, V. M.; Oro, J.

    1972-01-01

    Study of the mechanism of nonenzymic beta-decarboxylation of aspartic acid in the presence of metal ions and pyridoxal. The results suggest that aspartic acid is first converted to oxalacetic acid by transamination with pyridoxal which in turn is converted to pyridoxamine. This is followed by decarboxylation of oxalacetic acid to form pyruvic acid which transaminates with pyridoxamine to form alanine. The possible significance of these results to prebiotic molecular evolution is briefly discussed.

  15. Studies on the cyclization reaction of D-aspartic acid

    Institute of Scientific and Technical Information of China (English)

    Yu Chuan Li; Si Ping Pang; Yong Zhong Yu

    2007-01-01

    The cyclization reaction of D-aspartic acid was studied, the carboxyl groups of D-aspartic acid were protected by benzyl alcohol to give compound D-dibenzyl aspartate. Then (4R)-benzyl azetidine-2-one-4-carboxylate and meso-3,6-disubstituted piperazine2,5-diones were synthesized via intramolecular cyclization and intermolecular cyclization of D-dibenzyl aspartate, respectively, and their structures were confirmed by 1H NMR and MS. Both cyclization reaction conditions were also investigated in detail.

  16. Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose 5-phosphate binding

    DEFF Research Database (Denmark)

    Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

    1996-01-01

    an increase in KM for ribose 5-phosphate in the presence of at least one of the divalent metal ions Mg2+, Mn2+, Co2+, or Cd2+, with the most dramatic changes revealed by the D220E and D220F enzymes in the presence of Co2+ and the D221A enzyme in the presence of Mn2+ or Co2+. The D220F and D221A enzymes both...... showed large decreases in Vapp in the presence of the various divalent metal ions, except for the D221A enzyme in the presence of Co2+. Vapp of the D220E enzyme was similar to that of the wild-type enzyme in the presence of Mg2+, Mn2+, or Cd2+, whereas the Vapp was increased in the presence of Co2+. Vapp...... enzymes were dependent on the metal ion present, suggesting a function of the investigated aspartic acid residues both in the binding of ribose 5-phosphate, possibly via a divalent metal ion, and in the interaction with a divalent metal ion during catalysis...

  17. Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose-5-phosphate binding

    DEFF Research Database (Denmark)

    Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

    1996-01-01

    The three conserved aspartic acid residues of the 5-phospho-d-ribosyl a-1-diphosphate binding site (213-GRDCVLVDDMIDTGGT-228) of Escherichia coli phosphoribosyl diphosphate synthetase were studied by analysis of the mutant enzymes D220E, D220F, D221A, D224A, and D224S. The mutant enzymes showed...... an increase in KM for ribose 5-phosphate in the presence of at least one of the divalent metal ions Mg2+, Mn2+, Co2+, or Cd2+, with the most dramatic changes revealed by the D220E and D220F enzymes in the presence of Co2+ and the D221A enzyme in the presence of Mn2+ or Co2+. The D220F and D221A enzymes both...... showed large decreases in Vapp in the presence of the various divalent metal ions, except for the D221A enzyme in the presence of Co2+. Vapp of the D220E enzyme was similar to that of the wild-type enzyme in the presence of Mg2+, Mn2+, or Cd2+, whereas the Vapp was increased in the presence of Co2+. Vapp...

  18. Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose 5-phosphate binding

    DEFF Research Database (Denmark)

    Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

    1996-01-01

    The three conserved aspartic acid residues of the 5-phospho-D-ribosyl α-1-diphosphate binding site (213-GRDCVLVDDMIDTGGT-228) of Escherichia coli phosphoribosyl diphosphate synthetase were studied by analysis of the mutant enzymes D220E, D220F, D221A, D224A, and D224S. The mutant enzymes showed...... an increase in KM for ribose 5-phosphate in the presence of at least one of the divalent metal ions Mg2+, Mn2+, Co2+, or Cd2+, with the most dramatic changes revealed by the D220E and D220F enzymes in the presence of Co2+ and the D221A enzyme in the presence of Mn2+ or Co2+. The D220F and D221A enzymes both...... showed large decreases in Vapp in the presence of the various divalent metal ions, except for the D221A enzyme in the presence of Co2+. Vapp of the D220E enzyme was similar to that of the wild-type enzyme in the presence of Mg2+, Mn2+, or Cd2+, whereas the Vapp was increased in the presence of Co2+. Vapp...

  19. Vibrational spectroscopy of bacteriorhodopsin mutants: light-driven proton transport involves protonation changes of aspartic acid residues 85, 96, and 212

    Energy Technology Data Exchange (ETDEWEB)

    Braiman, M.S.; Mogi, T.; Marti, T.; Stern, L.J.; Khorana, H.G.; Rothschild, K.J.

    1988-11-15

    Fourier transform infrared (FTIR) difference spectra have been obtained for the bR----K, bR----L, and bR----M photoreactions in bacteriorhodopsin mutants in which Asp residues 85, 96, 115, and 212 have been replaced by Asn and by Glu. Difference peaks that had previously been attributed to Asp COOH groups on the basis of isotopic labeling were absent or shifted in these mutants. In general, each COOH peak was affected strongly by mutation at only one of the four residues. Thus, it was possible to assign each peak tentatively to a particular Asp. From these assignments, a model for the proton-pumping mechanism of bR is derived, which features proton transfers among Asp-85, -96, and -212, the chromophore Schiff base, and other ionizable groups within the protein. The model can explain the observed COOH peaks in the FTIR difference spectra of bR photointermediates and could also account for other recent results on site-directed mutants of bR.

  20. Conserved Aspartic Acid Residues Lining the Extracellular Loop I of Sodium-coupled Bile Acid Transporter ASBT Interact with Na+ and 7α-OH Moieties on the Ligand Cholestane Skeleton*

    Science.gov (United States)

    Hussainzada, Naissan; Da Silva, Tatiana Claro; Zhang, Eric Y.; Swaan, Peter W.

    2008-01-01

    Functional contributions of residues Val-99—Ser-126 lining extracellular loop (EL) 1 of the apical sodium-dependent bile acid transporter were determined via cysteine-scanning mutagenesis, thiol modification, and in silico interpretation. Despite membrane expression for all but three constructs (S112C, Y117C, S126C), most EL1 mutants (64%) were inactivated by cysteine mutation, suggesting a functional role during sodium/bile acid co-transport. A negative charge at conserved residues Asp-120 and Asp-122 is required for transport function, whereas neutralization of charge at Asp-124 yields a functionally active transporter. D124A exerts low affinity for common bile acids except deoxycholic acid, which uniquely lacks a 7α-hydroxyl (OH) group. Overall, we conclude that (i) Asp-122 functions as a Na+ sensor, binding one of two co-transported Na+ ions, (ii) Asp-124 interacts with 7α-OH groups of bile acids, and (iii) apolar EL1 residues map to hydrophobic ligand pharmacophore features. Based on these data, we propose a comprehensive mechanistic model involving dynamic salt bridge pairs and hydrogen bonding involving multiple residues to describe sodium-dependent bile acid transporter-mediated bile acid and cation translocation. PMID:18508772

  1. Roles of Copper and a Conserved Aspartic Acid in the Autocatalytic Hydroxylation of a Specific Tryptophan Residue during Cysteine Tryptophylquinone Biogenesis.

    Science.gov (United States)

    Williamson, Heather R; Sehanobish, Esha; Shiller, Alan M; Sanchez-Amat, Antonio; Davidson, Victor L

    2017-02-21

    The first posttranslational modification step in the biosynthesis of the tryptophan-derived quinone cofactors is the autocatalytic hydroxylation of a specific Trp residue at position C-7 on the indole side chain. Subsequent modifications are catalyzed by modifying enzymes, but the mechanism by which this first step occurs is unknown. LodA possesses a cysteine tryptophylquinone (CTQ) cofactor. Metal analysis as well as spectroscopic and kinetic studies of the mature and precursor forms of a D512A LodA variant provides evidence that copper is required for the initial hydroxylation of the precursor protein and that if alternative metals are bound, the modification does not occur and the precursor is unstable. It is shown that the mature native LodA also contains loosely bound copper, which affects the visible absorbance spectrum and quenches the fluorescence spectrum that is attributed to the mature CTQ cofactor. When copper is removed, the fluorescence appears, and when it is added back to the protein, the fluorescence is quenched, indicating that copper reversibly binds in the proximity of CTQ. Removal of copper does not diminish the enzymatic activity of LodA. This distinguishes LodA from enzymes with protein-derived tyrosylquinone cofactors in which copper is present near the cofactor and is absolutely required for activity. Mechanisms are proposed for the role of copper in the hydroxylation of the unactivated Trp side chain. These results demonstrate that the reason that the highly conserved Asp512 is critical for LodA, and possibly all tryptophylquinone enzymes, is not because it is required for catalysis but because it is necessary for CTQ biosynthesis, more specifically to facilitate the initial copper-dependent hydroxylation of a specific Trp residue.

  2. SCA1-Like Disease in Mice Expressing Wild Type Ataxin-1 with a Serine to Aspartic Acid Replacement at Residue 776

    Science.gov (United States)

    Duvick, Lisa; Barnes, Justin; Ebner, Blake; Agrawal, Smita; Andresen, Michael; Lim, Janghoo; Giesler, Glenn J.; Zoghbi, Huda Y.; Orr, Harry T.

    2010-01-01

    SUMMARY Glutamine tract expansion triggers nine neurodegenerative diseases by conferring toxic properties to the mutant protein. In SCA1, phosphorylation of ATXN1 at Ser776 is thought to be key for pathogenesis. Here we show that replacing Ser776 with a phospho-mimicking Asp converted ATXN1 with a wild type glutamine tract into a pathogenic protein. ATXN1[30Q]-D776-induced disease in Purkinje cells shared most features with disease caused by ATXN1[82Q] having an expanded polyglutamine tract. However, in contrast to disease induced by ATXN1[82Q] that progresses to cell death, ATXN1[30Q]-D776 failed to induce cell death. These results support a model where pathogenesis involves changes in regions of the protein in addition to the polyglutamine tract. In ATXN1, placing an Asp at residue 776 mimics this change. Moreover, disease initiation and progression to neuronal dysfunction are distinct from induction of cell death. Ser776 is critical for the pathway to neuronal dysfunction, while an expanded polyglutamine tract is essential for neuronal death. PMID:20869591

  3. Inhibition mechanism of aspartic acid on crystal growth of hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    HUANG Su-ping; ZHOU Ke-chao; LI Zhi-you

    2007-01-01

    The effects of aspartic acid on the crystal growth, morphology of hydroxyapatite(HAP) crystal were investigated, and the inhibition mechanism of aspartic acid on the crystal growth of hydroxyapatite was studied. The results show that the crystal growth rate of HAP decreases with the increase of the aspartic acid concentration, and the HAP crystal is thinner significantly compared with that without amino acid, which is mainly due to the (10(-)10) surface of HAP crystal being inhibited by the aspartic acids. The calculation analysis indicates that the crystal growth mechanism of HAP, following surface diffusion controlled mechanism, is not changed due to the presence of aspartic acid. AFM result shows that the front of terrace on vicinal growth hillocks is pinned, which suggests that the aspartic acid is adsorbed onto the (10(-)10) surface of HAP and interacts with the Ca2+ ions of HAP surface, so as to block the growth active sites and result in retarding of the growth of HAP crystal.

  4. Gas-phase Acidities of Aspartic Acid, Glutamic Acid, and their Amino Acid Amides.

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhong; Matus, Myrna H; Velazquez, Hector A; Dixon, David A; Cassady, Carolyn J

    2007-02-14

    Gas-phase acidities (GA or ΔGacid) for the two most acidic common amino acids, aspartic acid and glutamic acid, have been determined for the first time. Because of the amide linkage’s importance in peptides and as an aid in studying side chain versus main chain deprotonation, aspartic acid amide and glutamic acid amide were also studied. Experimental GA values were measured by proton transfer reactions in an electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer. Calculated GAs were obtained by density functional and molecular orbital theory approaches. The best agreement with experiment was found at the G3MP2 level; the MP2/CBS and B3LYP/aug-cc-pVDZ results are 3–4 kcal/mol more acidic than the G3MP2 results. Experiment shows that aspartic acid is more acidic than glutamic acid by ca. 3 kcal/mol whereas the G3MP2 results show a smaller acidity difference of 0.2 kcal/mol. Similarly, aspartic acid amide is experimentally observed to be ca. 2 kcal/mol more acidic than glutamic acid amide whereas the G3MP2 results show a correspondingly smaller energy difference of 0.7 kcal/mol. The computational results clearly show that the anions are all ring-like structures with strong hydrogen bonds between the OH or NH2 groups and the CO2- group from which the proton is removed. The two amino acids are main-chain deprotonated. In addition, use of the COSMO model for the prediction of the free energy differences in aqueous solution gave values in excellent agreement with the most recent experimental values for pKa. Glutamic acid is predicted to be more acidic than aspartic acid in aqueous solution due to differential solvation effects.

  5. Gas-phase acidities of aspartic acid, glutamic acid, and their amino acid amides

    Science.gov (United States)

    Li, Zhong; Matus, Myrna H.; Velazquez, Hector Adam; Dixon, David A.; Cassady, Carolyn J.

    2007-09-01

    Gas-phase acidities (GA or [Delta]Gacid) for the two most acidic common amino acids, aspartic acid and glutamic acid, have been determined for the first time. Because of the amide linkage's importance in peptides and as an aid in studying side chain versus main chain deprotonation, aspartic acid amide and glutamic acid amide were also studied. Experimental GA values were measured by proton transfer reactions in an electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer. Calculated GAs were obtained by density functional and molecular orbital theory approaches. The best agreement with experiment was found at the G3MP2 level; the MP2/CBS and B3LYP/aug-cc-pVDZ results are 3-4 kcal/mol more acidic than the G3MP2 results. Experiment shows that aspartic acid is more acidic than glutamic acid by ca. 3 kcal/mol whereas the G3MP2 results show a smaller acidity difference of 0.2 kcal/mol. Similarly, aspartic acid amide is experimentally observed to be ca. 2 kcal/mol more acidic than glutamic acid amide whereas the G3MP2 results show a correspondingly smaller energy difference of 0.7 kcal/mol. The computational results clearly show that the anions are all ring-like structures with strong hydrogen bonds between the OH or NH2 groups and the CO2- group from which the proton is removed. The two amino acids are main-chain deprotonated. In addition, use of the COSMO model for the prediction of the free energy differences in aqueous solution gave values in excellent agreement with the most recent experimental values for pKa. Glutamic acid is predicted to be more acidic than aspartic acid in aqueous solution due to differential solvation effects.

  6. Distinguishing Aspartic and Isoaspartic Acids in Peptides by Several Mass Spectrometric Fragmentation Methods

    Science.gov (United States)

    DeGraan-Weber, Nick; Zhang, Jun; Reilly, James P.

    2016-12-01

    Six ion fragmentation techniques that can distinguish aspartic acid from its isomer, isoaspartic acid, were compared. MALDI post-source decay (PSD), MALDI 157 nm photodissociation, tris(2,4,6-trimethoxyphenyl)phosphonium bromide (TMPP) charge tagging in PSD and photodissociation, ESI collision-induced dissociation (CID), electron transfer dissociation (ETD), and free-radical initiated peptide sequencing (FRIPS) with CID were applied to peptides containing either aspartic or isoaspartic acid. Diagnostic ions, such as the y-46 and b+H2O, are present in PSD, photodissociation, and charge tagging. c•+57 and z-57 ions are observed in ETD and FRIPS experiments. For some molecules, aspartic and isoaspartic acid yield ion fragments with significantly different intensities. ETD and charge tagging appear to be most effective at distinguishing these residues.

  7. The Reovirus Sigmal Aspartic Acid Sandwich: A Trimerization Motif Poised for Conformational Change

    Energy Technology Data Exchange (ETDEWEB)

    Schelling,P.; Guglielml, K.; Kirchner, E.; Paetzold, b.; Dermody, T.; Stehle, T.

    2007-01-01

    Reovirus attachment protein {sigma}1 mediates engagement of receptors on the surface of target cells and undergoes dramatic conformational rearrangements during viral disassembly in the endocytic pathway. The {sigma}1 protein is a filamentous, trimeric molecule with a globular {beta}-barrel head domain. An unusual cluster of aspartic acid residues sandwiched between hydrophobic tyrosines is located at the {sigma}1 subunit interface. A 1.75 {angstrom} structure of the {sigma}1 head domain now reveals two water molecules at the subunit interface that are held strictly in position and interact with neighboring residues. Structural and biochemical analyses of mutants affecting the aspartic acid sandwich indicate that these residues and the corresponding chelated water molecules act as a plug to block the free flow of solvent and stabilize the trimer. This arrangement of residues at the {sigma}1 head trimer interface illustrates a new protein design motif that may confer conformational mobility during cell entry.

  8. The reovirus sigma1 aspartic acid sandwich: a trimerization motif poised for conformational change.

    Science.gov (United States)

    Schelling, Pierre; Guglielmi, Kristen M; Kirchner, Eva; Paetzold, Bernhard; Dermody, Terence S; Stehle, Thilo

    2007-04-13

    Reovirus attachment protein sigma1 mediates engagement of receptors on the surface of target cells and undergoes dramatic conformational rearrangements during viral disassembly in the endocytic pathway. The sigma1 protein is a filamentous, trimeric molecule with a globular beta-barrel head domain. An unusual cluster of aspartic acid residues sandwiched between hydrophobic tyrosines is located at the sigma1 subunit interface. A 1.75-A structure of the sigma1 head domain now reveals two water molecules at the subunit interface that are held strictly in position and interact with neighboring residues. Structural and biochemical analyses of mutants affecting the aspartic acid sandwich indicate that these residues and the corresponding chelated water molecules act as a plug to block the free flow of solvent and stabilize the trimer. This arrangement of residues at the sigma1 head trimer interface illustrates a new protein design motif that may confer conformational mobility during cell entry.

  9. NEUTRALIZATION OF THE ASPARTIC ACID RESIDUE D367, BUT NOT D454, INHIBITS BINDING OF NA+ TO THE GLUTAMATE-FREE FORM AND CYCLING OF THE GLUTAMATE TRANSPORTER EAAC1

    Science.gov (United States)

    Tao, Zhen; Zhang, Zhou; Grewer, Christof

    2008-01-01

    Substrate transport by the plasma membrane glutamate transporter EAAC1 is coupled to cotransport of three sodium ions. One of these Na+ ions binds to the transporter already in the absence of glutamate. Here, we have investigated the possible involvement of two conserved aspartic acid residues in transmembrane segments 7 and 8 of EAAC1, D367 and D454, in Na+ cotransport. In order to test the effect of charge neutralization mutations in these positions on Na+ binding to the glutamate-free transporter, we recorded the Na+-induced anion leak current to determine the Km of EAAC1 for Na+. For EAAC1WT, this Km was determined as 120 mM. When the negative charge of D367 was neutralized by mutagenesis to asparagine, Na+ activated the anion leak current with a Km of about 2 M, indicating dramatically impaired Na+ binding to the mutant transporter. In contrast, the Na+ affinity of EAAC1D454N was virtually unchanged compared to the wild type transporter (Km = 90 mM). The reduced occupancy of the Na+ binding site of EAAC1D367N resulted in a dramatic reduction in glutamate affinity (Km = 3.6 mM, 140 mM [Na+]), which could be partially overcome by increasing extracellular [Na+]. In addition to impairing Na+ binding, the D367N mutation slowed glutamate transport, as shown by pre-steady-state kinetic analysis of transport currents, by strongly decreasing the rate of a reaction step associated with glutamate translocation. Our data are consistent with a model in which D367, but not D454 is involved in coordinating the bound Na+ in the glutamate-free transporter form. PMID:16478724

  10. Conserved aspartic acid 233 and alanine 231 are not required for poliovirus polymerase function in replicons

    Directory of Open Access Journals (Sweden)

    Freistadt Marion S

    2007-03-01

    Full Text Available Abstract Nucleic acid polymerases have similar structures and motifs. The function of an aspartic acid (conserved in all classes of nucleic acid polymerases in motif A remains poorly understood in RNA-dependent RNA polymerases. We mutated this residue to alanine in a poliovirus replicon. The resulting mutant could still replicate, although at a reduced level. In addition, mutation A231C (also in motif A yielded high levels of replication. Taken together these results show that poliovirus polymerase conserved residues D233 and A231 are not essential to poliovirus replicon function.

  11. Conserved aspartic acid 233 and alanine 231 are not required for poliovirus polymerase function in replicons

    Science.gov (United States)

    Freistadt, Marion S; Eberle, Karen E

    2007-01-01

    Nucleic acid polymerases have similar structures and motifs. The function of an aspartic acid (conserved in all classes of nucleic acid polymerases) in motif A remains poorly understood in RNA-dependent RNA polymerases. We mutated this residue to alanine in a poliovirus replicon. The resulting mutant could still replicate, although at a reduced level. In addition, mutation A231C (also in motif A) yielded high levels of replication. Taken together these results show that poliovirus polymerase conserved residues D233 and A231 are not essential to poliovirus replicon function. PMID:17352827

  12. [Application of aspartic acid as a non-specific binding inhibitor in the enrichment of phosphopeptides with titanium dioxide].

    Science.gov (United States)

    Chi, Ming; Bi, Wei; Lu, Zhuang; Song, Lina; Jia, Wei; Zhang, Yangjun; Qian, Xiaohong; Cai, Yun

    2010-02-01

    Titanium dioxide (TiO2) is one of metal oxides widely used for phosphopeptide enrichment in phosphoproteomic research nowadays. However it can bind to some non-phosphorylated peptides containing one or more aspartic acid residues and/or glutamic acid residues. These non-phosphorylated peptides can be eluted along with phosphorylated peptides and cause the reduction of the selectivity. Conventional inhibitors for the non-specific binding of non-phosphorylated peptides can often contaminate the ion source of mass spectrometry and therefore their applications are limited in liquid chromatography-mass spectrometry (LC-MS). In this study, aspartic acid was reported as a novel non-specific binding inhibitor for phosphopeptide enrichment by titanium dioxide. Firstly, the tryptic peptide mixtures of 3 and 9 standard proteins were used for the comparison of the enrichment efficiency of titanium dioxide. The effects with the presence of aspartic acid, glutamic acid and no-inhibitor in the enrichment systems were compared separately. The results showed that aspartic acid can greatly improve the selectivity of titanium dioxide for phosphopeptide enrichment. Then, aspartic acid was used for the enrichment of tryptic peptide mixture of C57BL/6J mouse liver lysate and good results were also obtained which demonstrated that aspartic acid was a promising non-specific binding inhibitor for complex biological samples. Besides, no contamination in the ion source occurred during the mass spectrometric analysis.

  13. Biodegradability and tissue reaction of random copolymers of L-leucine, L-aspartic acid, and L-aspartic acid esters

    NARCIS (Netherlands)

    Marck, K.W.; Wildevuur, Ch.R.H.; Sederel, W.L.; Bantjes, A.; Feijen, J.

    1977-01-01

    A series of copoly(α-amino acids) with varying percentages of hydrophilic (l-aspartic acid) and hydrophobic monomers (l-leucine, ß-methyl-l-aspartate, and ß-benzyl-l-aspartate) were implanted subcutaneously in rats and the macroscopic degradation behavior was studied. Three groups of materials (A, B

  14. Properties of Copolymers of Aspartic Acid and Aliphatic Dicarboxylic Acids Prepared by Reactive Extrusion

    Science.gov (United States)

    Aspartic acid may be prepared chemically or by the fermentation of carbohydrates. Currently, low molecular weight polyaspartic acids are prepared commercially by heating aspartic acid at high temperatures (greater than 220 degrees C) for several hours in the solid state. In an effort to develop a ...

  15. 2-Methyl­aspartic acid monohydrate

    OpenAIRE

    Brewer, Greg; Burton, Aaron S.; Dworkin, Jason P.; Butcher, Ray J.

    2013-01-01

    The title compound, C5H9NO4·H2O, is an isomer of the α-amino acid glutamic acid that crystallizes from water in its zwitterionic form as a monohydrate. It is not one of the 20 proteinogenic α-amino acids that are used in living systems and differs from the natural amino acids in that it has an α-methyl group rather than an α-H atom. In the crystal, an O—H⋯O hydrogen bond is present between the acid and water mol­ecules while extensive N—H⋯O and O—H⋯O hydrogen bonds link the components into a ...

  16. Behavior of aspartic acid as a corrosion inhibitor for steel

    Energy Technology Data Exchange (ETDEWEB)

    Kalota, D.J.; Silverman, D.C. (Monsanto Co., St. Louis, MO (United States))

    1994-02-01

    Corrosion inhibition of steel by aspartic acid (C[sub 4]H[sub 7]NO[sub 4]), an amino acid of low molecular weight, was found to depend strongly on pH. At a pH less than the ionization constant at [approximately]9.5 to 10 (measured at 25 C), C[sub 4]H[sub 7]NO[sub 4] appeared to accelerate corrosion. Above the pH, it acted as a corrosion inhibitor for steel. A specially constructed potential-pH diagram for iron (Fe) that incorporated C[sub 4]H[sub 7]NO[sub 4] showed the change in behavior was accompanied by the most stable thermodynamic state changing from an iron aspartate complex to iron oxide. Polymerized C[sub 4]H[sub 7]NO[sub 4] (polyaspartic acid) behaved in a similar manner. Some other amino acids of low molecular weight behaved similarly.

  17. Synthesis of 6-phosphofructose aspartic acid and some related Amadori compounds.

    Science.gov (United States)

    Hansen, Alexandar L; Behrman, Edward J

    2016-08-05

    We describe the synthesis and characterization of 6-phosphofructose-aspartic acid, an intermediate in the metabolism of fructose-asparagine by Salmonella. We also report improved syntheses of fructose-asparagine itself and of fructose-aspartic acid.

  18. The (unusual) aspartic acid in the metal coordination sphere of the prokaryotic zinc finger domain.

    Science.gov (United States)

    D'Abrosca, Gianluca; Russo, Luigi; Palmieri, Maddalena; Baglivo, Ilaria; Netti, Fortuna; de Paola, Ivan; Zaccaro, Laura; Farina, Biancamaria; Iacovino, Rosa; Pedone, Paolo Vincenzo; Isernia, Carla; Fattorusso, Roberto; Malgieri, Gaetano

    2016-08-01

    The possibility of choices of protein ligands and coordination geometries leads to diverse Zn(II) binding sites in zinc-proteins, allowing a range of important biological roles. The prokaryotic Cys2His2 zinc finger domain (originally found in the Ros protein from Agrobacterium tumefaciens) tetrahedrally coordinates zinc through two cysteine and two histidine residues and it does not adopt a correct fold in the absence of the metal ion. Ros is the first structurally characterized member of a family of bacterial proteins that presents several amino acid changes in the positions occupied in Ros by the zinc coordinating residues. In particular, the second position is very often occupied by an aspartic acid although the coordination of structural zinc by an aspartate in eukaryotic zinc fingers is very unusual. Here, by appropriately mutating the protein Ros, we characterize the aspartate role within the coordination sphere of this family of proteins demonstrating how the presence of this residue only slightly perturbs the functional structure of the prokaryotic zinc finger domain while it greatly influences its thermodynamic properties.

  19. Bioproduction of L-Aspartic Acid and Cinnamic Acid by L-Aspartate Ammonia Lyase from Pseudomonas aeruginosa PAO1.

    Science.gov (United States)

    Patel, Arti T; Akhani, Rekha C; Patel, Manisha J; Dedania, Samir R; Patel, Darshan H

    2016-12-17

    Aspartase (L-aspartate ammonia lyase, EC 4.3.1.1) catalyses the reversible amination and deamination of L-aspartic acid to fumaric acid which can be used to produce important biochemical. In this study, we have explored the characteristics of aspartase from Pseudomonas aeruginosa PAO1 (PA-AspA). To overproduce PA-AspA, the 1425-bp gene was introduced in Escherichia coli BL21 and purified. A 51.0-kDa protein was observed as a homogenous purified protein on SDS-PAGE. The enzyme was optimally active at pH 8.0 and 35 °C. PA-AspA has retained 56% activity after 7 days of incubation at 35 °C, which displays the hyperthermostablility characteristics of the enzyme. PA-AspA is activated in the presence of metal ions and Mg2+ is found to be most effective. Among the substrates tested for specificity of PA-AspA, L-phenylalanine (38.35 ± 2.68) showed the highest specific activity followed by L-aspartic acid (31.21 ± 3.31) and fumarate (5.42 ± 2.94). K m values for L-phenylalanine, L-aspartic acid and fumarate were 1.71 mM, 0.346 μM and 2 M, respectively. The catalytic efficiency (k cat/K m) for L-aspartic acid (14.18 s(-1) mM(-1)) was higher than that for L-phenylalanine (4.65 s(-1) mM(-1)). For bioconversion, from an initial concentration of 1000 mM of fumarate and 30 mM of L-phenylalanine, PA-AspA was found to convert 395.31 μM L-aspartic acid and 3.47 mM cinnamic acid, respectively.

  20. Three-dimensional hybrid networks based on aspartic acid

    Indian Academy of Sciences (India)

    Anupama Ghosh; R A Sanguramath

    2008-01-01

    Three-dimensional achiral coordination polymers of the general formula M2(D, L-NHCH (COO)CH2COO)2.C4H4N2 where M = Ni and Co and pyrazine acts as the linker molecule have been prepared under hydrothermal conditions starting with [M(L-NHCH(COO)CH2COO).3H2O] possessing a helical chain structure. A three-dimensional hybrid compound of the formula Pb2.5[N{CH(COO)CH2COO}22H2O] has also been prepared hydrothermally starting with aspartic acid and Pb(NO3)2. In this lead compound, where a secondary amine formed by the dimerisation of aspartic acid acts as the ligand, there is two-dimensional inorganic connectivity and one-dimensional organic connectivity.

  1. Explosive enantiospecific decomposition of aspartic acid on Cu surfaces.

    Science.gov (United States)

    Mhatre, B S; Dutta, S; Reinicker, A; Karagoz, B; Gellman, A J

    2016-12-01

    Aspartic acid adsorbed on Cu surfaces is doubly deprotonated. On chiral Cu(643)(R&S) its enantiomers undergo enantiospecific decomposition via an autocatalytic explosion. Once initiated, the decomposition mechanism proceeds via sequential cleavage of the C3-C4 and C1-C2 bonds each yielding CO2, followed by conversion of the remaining species into N[triple bond, length as m-dash]CCH3.

  2. On the solvation of L-aspartic acid

    Science.gov (United States)

    Paxton, A. T.; Harper, J. B.

    2004-01-01

    We use molecular statics and dynamics to study the stability of L-aspartic acid both in vacuo and solvated by polar and non-polar molecules using density functional theory in the generalized gradient approximation. We find that structures stable in vacuo are unstable in aqueous solution and vice versa. From our simulations we are able to come to some conclusions about the mechanism of stabilisation of zwitterions by polar protic solvents, water and methanol.

  3. Extraction of L-Aspartic Acid with Reverse Micelle System

    Directory of Open Access Journals (Sweden)

    Özlem AYDOĞAN

    2009-02-01

    Full Text Available The aim of this study is to investigate the extraction L-aspartic acid which is a hydrophobic amino acid with reverse micelle system. Production of amino acids by fermentation has been more important in recent years. These amino acids are obtained in dilute aqueous solutions and have to be separated from excess substrate, inorganic salts and by-products. Recently, separation of amino acids from fermentation media by reverse micelle extraction has received a great deal of attention. In this study, reverse micelle phase includes aliquat-336 as a surfactant, 1-decanol as a co-surfactant and isooctane as an apolar solvent. Experiments were performed at 150 rpm stirring rate, at 30 oC, for 30 min extraction time with equal volumes of reverse micelle and aqueous phases. Concentration of L-aspartic acid was analyzed by liquid chromatography (HPLC. The extraction yield increased with increasing pH and aliquat-336 concentration and with decreasing initial amino acid concentration. Maximum ekstraction yield (68 % was obtained at pH of 12, surfactant concentration of 200 mM and an initial amino acid concentration of 5 mM.

  4. Structural evidence for solvent-stabilisation by aspartic acid as a mechanism for halophilic protein stability in high salt concentrations.

    Science.gov (United States)

    Lenton, Samuel; Walsh, Danielle L; Rhys, Natasha H; Soper, Alan K; Dougan, Lorna

    2016-07-21

    Halophilic organisms have adapted to survive in high salt environments, where mesophilic organisms would perish. One of the biggest challenges faced by halophilic proteins is the ability to maintain both the structure and function at molar concentrations of salt. A distinct adaptation of halophilic proteins, compared to mesophilic homologues, is the abundance of aspartic acid on the protein surface. Mutagenesis and crystallographic studies of halophilic proteins suggest an important role for solvent interactions with the surface aspartic acid residues. This interaction, between the regions of the acidic protein surface and the solvent, is thought to maintain a hydration layer around the protein at molar salt concentrations thereby allowing halophilic proteins to retain their functional state. Here we present neutron diffraction data of the monomeric zwitterionic form of aspartic acid solutions at physiological pH in 0.25 M and 2.5 M concentration of potassium chloride, to mimic mesophilic and halophilic-like environmental conditions. We have used isotopic substitution in combination with empirical potential structure refinement to extract atomic-scale information from the data. Our study provides structural insights that support the hypothesis that carboxyl groups on acidic residues bind water more tightly under high salt conditions, in support of the residue-ion interaction model of halophilic protein stabilisation. Furthermore our data show that in the presence of high salt the self-association between the zwitterionic form of aspartic acid molecules is reduced, suggesting a possible mechanism through which protein aggregation is prevented.

  5. N-methyl-D-aspartic acid receptor agonists

    DEFF Research Database (Denmark)

    Madsen, U; Frydenvang, Karla Andrea; Ebert, B

    1996-01-01

    (R,S)-2-Amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid [(R,S)-AMAA, 4] is a potent and selective agonist at the N-methyl-D-aspartic acid (NMDA) subtype of excitatory amino acid receptors. Using the Ugi "four-component condensation" method, the two diastereomers (2R)- and (2S)-2-[3-(benzyloxy......) showed peak affinity for [3H]AMPA receptor sites (IC50 = 72 +/- 13 microM) and was shown to be a more potent inhibitor of [3H]CPP binding (IC50 = 3.7 +/- 1.5 microM) than (S)-AMAA (9) (IC50 = 61 +/- 6.4 microM). Neither enantiomer of AMAA affected [3H]kainic acid receptor binding significantly...

  6. Aspartic acid interaction with cobalt(II) in dilute aqueous solution: A {sup 57}Co emission Moessbauer spectroscopic study

    Energy Technology Data Exchange (ETDEWEB)

    Kamnev, Alexander A.; Tugarova, Anna V. [Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences (Russian Federation); Kovacs, Krisztina; Homonnay, Zoltan, E-mail: homonnay@ludens.elte.hu; Kuzmann, Erno; Vertes, Attila [Eoetvoes Lorand University, Institute of Chemistry (Hungary)

    2012-03-15

    Emission ({sup 57}Co) Moessbauer spectra of the aspartic acid-{sup 57}CoCl{sub 2} system were measured at T = 80 K in frozen aqueous solution and in the form of a dried residue of this solution. The Moessbauer spectra, besides a weak contribution from after-effects, showed two Fe{sup 2 + }/Co{sup 2 + } components which were ascribed to octahedrally and tetrahedrally coordinated {sup 57}Co{sup II} microenvironments in the Asp-cobalt(II) complex. This dual coordination mode may be due to the involvement of the second terminal carboxylic group of aspartic acid in the coordination sphere of Co.

  7. Origins of hydration differences in homochiral and racemic crystals of aspartic acid.

    Science.gov (United States)

    Juliano, Thomas R; Korter, Timothy M

    2015-02-26

    The propensity for crystalline hydrates of organic molecules to form is related to the strength of the interactions between molecules, including the chiral composition of the molecular solids. Specifically, homochiral versus racemic crystalline samples can exhibit distinct differences in their ability to form energetically stable hydrates. The focus of the current study is a comparison of the crystal structures and intermolecular forces found in solid-state L-aspartic acid, DL-aspartic acid, and L-aspartic acid monohydrate. The absence of experimental evidence for the DL-aspartic acid monohydrate is considered here in terms of the enhanced thermodynamic stability of the DL-aspartic acid anhydrate crystal as compared to the L-aspartic acid anhydrate as revealed through solid-state density functional theory calculations and terahertz spectroscopic measurements. The results indicate that anhydrous DL-aspartic acid is the more stable solid, not due to intermolecular forces alone but also due to the improved conformations of the molecules within the racemic solid. Hemihydrated and monohydrated forms of DL-aspartic acid have been computationally evaluated, and in each case, the hydrates produce destabilized aspartic acid conformations that prevent DL-aspartic acid hydrate formation from occurring.

  8. 2-(hydroxymethyl)aspartic acid: synthesis, crystal structure, and reaction with a transaminase

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, J.J.; Metzler, D.E.; Powell, D.; Jacobson, R.A.

    1980-11-05

    The synthesis and x-ray crystal structure of 2-(hydroxymethyl) aspartic acid and the preliminary evaluation of its interaction with cytosolic aspartate aminotransferase of pig heart are described. A dissociation constant 1.4 mM for the L-2-(hydroxymethyl) aspartate complex with the enzyme was obtained. 2 figures. (DP)

  9. Interaction Between Some Monosaccharides and Aspartic Acid in Dilute Aqueous Solutions

    Science.gov (United States)

    Kulikova, Galina A.

    2008-01-01

    Interaction between aspartic acid and d-glucose, d-galactose, and d-fructose has been studied by isothermal titration calorimetry, calorimetry of dissolution, and densimetry. It has been found that d-glucose and d-fructose form thermodynamically stable associates with aspartic acid, in contrast to d-galactose. The selectivity in the interaction of aspartic acid with monosaccharides is affected by their stereochemical structures. PMID:19669542

  10. D-aspartic acid in aged mouse skin and lens

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Noriko; Muraoka, Shiro; Harada, Kaoru; Tamanoi, Itsuro; Joshima, Hisamasa; Kashima, Masatoshi

    1987-03-01

    D-aspartic acid (D-Asp) was detected in the skin and lens from naturally aged mice. An analysis of the amino acid composition indicated that D-Asp did not derive from collagen. An immunological analysis using Oucterlony's agar diffusion method also confirmed that the protein containing D-Asp was not a serum protein. The process producing D-Asp is regarded as one other than racemization because the life span of mice is not long enough to permit D-Asp by racemization. Continuous low-dose-rate gamma-irradiation (37R per day) for 102 to 112 days did not increase significantly the amount of D-Asp in skin and lens of mice.

  11. Analysis of the aspartic acid metabolic pathway using mutant genes.

    Science.gov (United States)

    Azevedo, R A

    2002-01-01

    Amino acid metabolism is a fundamental process for plant growth and development. Although a considerable amount of information is available, little is known about the genetic control of enzymatic steps or regulation of several pathways. Much of the information about biochemical pathways has arisen from the use of mutants lacking key enzymes. Although mutants were largely used already in the 60's, by bacterial and fungal geneticists, it took plant research a long time to catch up. The advance in this area was rapid in the 80's, which was followed in the 90's by the development of techniques of plant transformation. In this review we present an overview of the aspartic acid metabolic pathway, the key regulatory enzymes and the mutants and transgenic plants produced for lysine and threonine metabolism. We also discuss and propose a new study of high-lysine mutants.

  12. Growth and characterization of KDP crystals doped with L-aspartic acid

    Science.gov (United States)

    Krishnamurthy, R.; Rajasekaran, R.; Samuel, Bincy Susan

    2013-03-01

    Potassium Dihydrogen Phosphate (KDP) doped with L-aspartic acid has been grown by solvent slow evaporation technique from a mixture of aqueous solution of KDP and 0.7% of L-aspartic acid at room temperature. The grown crystals were characterized by powder X-ray diffraction, UV-visible, FTIR analysis. The doping of aspartic acid was confirmed by FTIR spectrum. The Nonlinear optical property (SHG) of L-aspartic acid doped KDP has been confirmed. Microhardness studies were carried out on the grown crystal.

  13. Aspartic acid interaction with cobalt(II) in dilute aqueous solution: A 57Co emission Mössbauer spectroscopic study

    Science.gov (United States)

    Kamnev, Alexander A.; Tugarova, Anna V.; Kovács, Krisztina; Homonnay, Zoltan; Kuzmann, Erno; Vértes, Attila

    2012-03-01

    Emission (57Co) Mössbauer spectra of the aspartic acid—57CoCl2 system were measured at T = 80 K in frozen aqueous solution and in the form of a dried residue of this solution. The Mössbauer spectra, besides a weak contribution from after-effects, showed two Fe2 + /Co2 + components which were ascribed to octahedrally and tetrahedrally coordinated 57CoII microenvironments in the Asp-cobalt(II) complex. This dual coordination mode may be due to the involvement of the second terminal carboxylic group of aspartic acid in the coordination sphere of Co.

  14. Determination of aqueous acid-dissociation constants of aspartic acid using PCM/DFT method

    Science.gov (United States)

    Sang-Aroon, Wichien; Ruangpornvisuti, Vithaya

    Determination of acid-dissociation constants, pKa, of aspartic acid in aqueous solution, using density functional theory calculations combined with the conductor-like polarizable continuum model (CPCM) and with integral-equation-formalism polarizable continuum model (IEFPCM) based on the UAKS and UAHF radii, was carried out. The computed pKa values derived from the CPCM and IEFPCM with UAKS cavity model of bare structures of the B3LYP/6-31+G(d,p)-optimized tetrahydrated structures of aspartic acid species are mostly close to the experimental pKa values.0

  15. Crystal structure of caesium hydrogen (L)-aspartate and an overview of crystalline compounds of aspartic acid with inorganic constituents

    Energy Technology Data Exchange (ETDEWEB)

    Fleck, M. [Universitaet Wien (Austria). Institut fuer Mineralogie und Kristallographie; Emmerich, R.; Bohaty, L. [Universitaet zu Koeln (Austria). Institut fuer Kristallographie

    2010-08-15

    The crystal structure of the new polar compound caesium hydrogen (L)-aspartate, Cs(C{sub 4}H{sub 6}NO{sub 4}), (abbreviated: Cs(L -AspH)) was determined from single crystal X-ray diffraction data; it comprises two crystallographically different L -AspH anions that are connected via caesium cations to form a three dimensional framework. The Cs ions are irregularly sevenfold[Cs1O{sub 7}] respectively eightfold[Cs2O{sub 8}] coordinated to all {alpha}- and {beta}- carboxylate oxygen atoms. Cs(L -AspH) represents a novel structure type of its own, as do most compounds of (L)-aspartic acid with inorganic constituents. A brief summary of such structurally known aspartates is given. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Preparation and enantiosorption of L-aspartic acid pillared hydrotalcites

    Institute of Scientific and Technical Information of China (English)

    PENG Xia-hui; HUANG Ke-long

    2007-01-01

    L-aspartic acid (Asp) pillared hydrotalcites were prepared by direct reaction of the L-Asp anion with layered double hydroxides (LDHs). The obtained samples were characterized by X-ray diffractometry (XRD), Fourier transform infrared (FTIR),and thermogravimetric and differential thermal analysis (TG/DTA). The results show that the initial interlayer carbonate ions can be completely replaced by the L-Asp anion under the controlled conditions. The pillared hydrotalcites have a crystallized supramolecular structure and thermal stability. The L-Asp pillared LDHs were used in the enantiosorption of enantiopure phenylalanine (Phe), the results suggest that L-Asp pillared LDHs exhibit an excellent enantiosorption capability for D-Phe, and the adsorption isotherm fits Freundlich equation.

  17. A Potent, Versatile Disulfide-Reducing Agent from Aspartic Acid

    Science.gov (United States)

    2013-01-01

    Dithiothreitol (DTT) is the standard reagent for reducing disulfide bonds between and within biological molecules. At neutral pH, however, >99% of DTT thiol groups are protonated and thus unreactive. Herein, we report on (2S)-2-amino-1,4-dimercaptobutane (dithiobutylamine or DTBA), a dithiol that can be synthesized from l-aspartic acid in a few high-yielding steps that are amenable to a large-scale process. DTBA has thiol pKa values that are ∼1 unit lower than those of DTT and forms a disulfide with a similar E°′ value. DTBA reduces disulfide bonds in both small molecules and proteins faster than does DTT. The amino group of DTBA enables its isolation by cation-exchange and facilitates its conjugation. These attributes indicate that DTBA is a superior reagent for reducing disulfide bonds in aqueous solution. PMID:22353145

  18. Microwave-Assisted Synthesis of Poly(Aspartic Acid-Itaconic Acid) Copolymer and Its Characterization

    Institute of Scientific and Technical Information of China (English)

    Zhang Yuling; Jiang Yijian; Hu Zhiguang; Wei Hanxiao; Guo Jun; Wang Jilong

    2016-01-01

    Poly(aspartic acid-itaconic acid) copolymer was synthesized from aspartic acid (Asp) and itaconic acid (Ita) un-der microwave irradiation. The effects of microwave power, microwave irradiation time, molar ratio of itaconic acid and aspartic acid, catalyst type, catalyst and organic solvent content on copolymer yield, and the performance for inhibition of CaCO3 fouling were investigated. It was found that the product yield achieved a highest record of 95% when the amount of catalyst NaH2PO4was 0.012 mol, the amount of organic solvent propylene carbonate was 16 mL, the molar ratio of Asp/Ita was 3:1, the microwave output power was 1200 W and the irradiation time was 5.5 min. And the product performance for inhibition of calcium carbonate also reached a highest value of 94.38%. Structural characterization of the product showed that the product was the aspartic acid-itaconic acid copolymer.

  19. Structural and Functional Importance of Transmembrane Domain 3 (TM3) in the Aspartate:Alanine Antiporter AspT: Topology and Function of the Residues of TM3 and Oligomerization of AspT▿

    OpenAIRE

    Nanatani, Kei; Maloney, Peter C.; Abe, Keietsu

    2009-01-01

    AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, a membrane protein of 543 amino acids with 10 putative transmembrane (TM) helices, is the prototype of the aspartate:alanine exchanger (AAE) family of transporters. Because TM3 (isoleucine 64 to methionine 85) has many amino acid residues that are conserved among members of the AAE family and because TM3 contains two charged residues and four polar residues, it is thought to be located near (or to form part of) the substrat...

  20. Plastidic aspartate aminotransferases and the biosynthesis of essential amino acids in plants.

    Science.gov (United States)

    de la Torre, Fernando; Cañas, Rafael A; Pascual, M Belén; Avila, Concepción; Cánovas, Francisco M

    2014-10-01

    In the chloroplasts and in non-green plastids of plants, aspartate is the precursor for the biosynthesis of different amino acids and derived metabolites that play distinct and important roles in plant growth, reproduction, development or defence. Aspartate biosynthesis is mediated by the enzyme aspartate aminotransferase (EC 2.6.1.1), which catalyses the reversible transamination between glutamate and oxaloacetate to generate aspartate and 2-oxoglutarate. Plastids contain two aspartate aminotransferases: a eukaryotic-type and a prokaryotic-type bifunctional enzyme displaying aspartate and prephenate aminotransferase activities. A general overview of the biochemistry, regulation, functional significance, and phylogenetic origin of both enzymes is presented. The roles of these plastidic aminotransferases in the biosynthesis of essential amino acids are discussed.

  1. Adsorption of Aspartic Acid onto Rutile: Implications for Biochirality

    Science.gov (United States)

    Estrada, C. F.; Jonsson, C. M.; Jonsson, C. L.; Sverjensky, D. A.; Hazen, R. M.

    2008-12-01

    Mineral surfaces may have facilitated the concentration and polymerization of simple biomolecules into macromolecules while promoting the development of biochirality. In this study, rutile and aspartic acid (Asp) were investigated as a possible system in this scenario. Batch adsorption experiments were performed to examine the adsorption of Asp as a function of total concentration and pH. A constant background electrolyte of 0.1 M NaCl was applied to the system, and all solutions were purged with argon gas to eliminate carbon dioxide contamination. Asp adsorbs onto rutile to the highest extent over the pH range 3-5.5 suggesting that an acidic environment is required for the adsorption between Asp and rutile to occur in significant amounts. This pH range of maximum adsorption is constrained between the isoelectric point of Asp and the point of zero charge of rutile, which indicates that electrostatic effects are influencing Asp adsorption. Both the L- and D- enantiomers of Asp were individually adsorbed onto the rutile surface to determine the potential of the system for chiral selection. Preliminary results indicate that D-Asp may possibly adsorb in greater amounts than L-Asp at higher Asp total concentrations. This trend is unexpected as the growth planes dominating the rutile are achiral, and a more thorough study is required to validate this difference in adsorption. Nevertheless, this result may provide insight on the emergence of chiral selection in macromolecules within what might be a predominantly achiral prebiotic system.

  2. Synthesis and Molecular Recognition of Novel Cyclic Pseudopeptides Containing L-Glutamic Acid or L-Aspartic Acid Backbones

    Institute of Scientific and Technical Information of China (English)

    WANG Tao王涛; HUANG Xiao-Yi黄小毅; XIA Chuan-Qin夏传琴; YU Xiao-Qi余孝其; XIE Ru-Gang谢如刚

    2004-01-01

    Novel cyclic pseudopeptides containing L-glutamic acid or L-aspartic acid backbone structures were efficiently synthesized and characterized. Their chiral recognition properties for L- and D-amino acid methyl ester hydrochloride were discussed also.

  3. SYNTHESIS AND CHARACTERIZATION OF POLY(L-GLUTAMIC ACID-co-L-ASPARTIC ACID)

    Institute of Scientific and Technical Information of China (English)

    Ling-ling Wang; Yi-xian Wu; Ri-wei Xu; Guan-ying Wu; Wan-tai Yang

    2008-01-01

    Poly(amino acid) has been widely utilized in drug delivery, tissue engineering and biomedical materials. Thebiomateriais based on poly(glutamic acid) are usually modified via copolymerization with other monomers such as L-asparticacid to improve the uncontrolled degradation rate. The ring-opening homo- and co-polymerization of y-benzyl-L-glutamateN-carboxyanhydride (BLG-NCA) and β-benzyl-L-aspartate N-carboxyanhydride (BLA-NCA) were carried out in solution byusing triethylamine (TEA) as initiator. The BLG-NCA homopolymerization could take place even at-30℃ and molecularweight of poly(γ-benzyl-L-glutamate) decreased with increasing polymerization temperature. The BLA-NCA polymerizationdid not occur at -10℃ and was needed to be carried out at 25℃ to improve the polymerization. Poly(γ-benzyl-L-glutamate)and poly(β-benzyl-L-aspartate) with unimodal molecular weigh distribution and weight average molecular weight (Mw) of32100 and 4000 could be obtained at 25℃. The copolymers of γ-benzyl L-glutamate and β-benzyl L-aspartate withunimodal molecular weight distribution and Mw ranging from 5600 to 24600 could be prepared. The useful copolymers ofpoly(L-glutamic acid-co-L-aspartic acid) were further prepared by removal of benzyl groups.

  4. Aspartic acid-484 of nascent placental alkaline phosphatase condenses with a phosphatidylinositol glycan to become the carboxyl terminus of the mature enzyme.

    Science.gov (United States)

    Micanovic, R; Bailey, C A; Brink, L; Gerber, L; Pan, Y C; Hulmes, J D; Udenfriend, S

    1988-01-01

    A carboxyl-terminal chymotryptic peptide from mature human placental alkaline phosphatase was purified by HPLC and monitored by a specific RIA. Sequencing and amino acid assay showed that the carboxyl terminus of the peptide was aspartic acid, representing residue 484 of the proenzyme as deduced from the corresponding cDNA. Further analysis of the peptide showed it to be a peptidoglycan containing one residue of ethanolamine, one residue of glucosamine, and two residues of neutral hexose. The inositol glycan is apparently linked to the alpha carboxyl group of the aspartic acid through the ethanolamine. Location of the inositol glycan on Asp-484 of the proenzyme indicates that a 29-residue peptide is cleaved from the nascent protein during the post-translational condensation with the phosphatidylinositol-glycan. PMID:3422741

  5. Supermacroporous chemically cross-linked poly(aspartic acid) hydrogels.

    Science.gov (United States)

    Gyarmati, Benjámin; Mészár, E Zsuzsanna; Kiss, Lóránd; Deli, Mária A; László, Krisztina; Szilágyi, András

    2015-08-01

    Chemically cross-linked poly(aspartic acid) (PASP) gels were prepared by a solid-liquid phase separation technique, cryogelation, to achieve a supermacroporous interconnected pore structure. The precursor polymer of PASP, polysuccinimide (PSI) was cross-linked below the freezing point of the solvent and the forming crystals acted as templates for the pores. Dimethyl sulfoxide was chosen as solvent instead of the more commonly used water. Thus larger temperatures could be utilized for the preparation and the drawback of increase in specific volume of water upon freezing could be eliminated. The morphology of the hydrogels was characterized by scanning electron microscopy and interconnectivity of the pores was proven by the small flow resistance of the gels. Compression tests also confirmed the interconnected porous structure and the complete re-swelling and shape recovery of the supermacroporous PASP hydrogels. The prepared hydrogels are of interest for several biomedical applications as scaffolding materials because of their cytocompatibility, controllable morphology and pH-responsive character.

  6. Combination of aspartic acid and glutamic acid inhibits tumor cell proliferation.

    Science.gov (United States)

    Yamaguchi, Yoshie; Yamamoto, Katsunori; Sato, Yoshinori; Inoue, Shinjiro; Morinaga, Tetsuo; Hirano, Eiichi

    2016-01-01

    Placental extract contains several biologically active compounds, and pharmacological induction of placental extract has therapeutic effects, such as improving liver function in patients with hepatitis or cirrhosis. Here, we searched for novel molecules with an anti-tumor activity in placental extracts. Active molecules were separated by chromatographic analysis, and their antiproliferative activities were determined by a colorimetric assay. We identified aspartic acid and glutamic acid to possess the antiproliferative activity against human hepatoma cells. Furthermore, we showed that the combination of aspartic acid and glutamic acid exhibited enhanced antiproliferative activity, and inhibited Akt phosphorylation. We also examined in vivo tumor inhibition activity using the rabbit VX2 liver tumor model. The treatment mixture (emulsion of the amino acids with Lipiodol) administered by hepatic artery injection inhibited tumor cell growth of the rabbit VX2 liver. These results suggest that the combination of aspartic acid and glutamic acid may be useful for induction of tumor cell death, and has the potential for clinical use as a cancer therapeutic agent.

  7. Selective fluorescent detection of aspartic acid and glutamic acid employing dansyl hydrazine dextran conjugate.

    Science.gov (United States)

    Nasomphan, Weerachai; Tangboriboonrat, Pramuan; Tanapongpipat, Sutipa; Smanmoo, Srung

    2014-01-01

    Highly water soluble polymer (DD) was prepared and evaluated for its fluorescence response towards various amino acids. The polymer consists of dansyl hydrazine unit conjugated into dextran template. The conjugation enhances higher water solubility of dansyl hydrazine moiety. Of screened amino acids, DD exhibited selective fluorescence quenching in the presence of aspartic acid (Asp) and glutamic acid (Glu). A plot of fluorescence intensity change of DD against the concentration of corresponding amino acids gave a good linear relationship in the range of 1 × 10(-4) M to 25 × 10(-3) M. This establishes DD as a potential polymeric sensor for selective sensing of Asp and Glu.

  8. Aspartic acid 413 is important for the normal allosteric functioning of ADP-glucose pyrophosphorylase

    Energy Technology Data Exchange (ETDEWEB)

    Greene, T.W.; Woodbury, R.L.; Okita, T.W. [Washington State Univ., Pullman, WA (United States)

    1996-11-01

    As part of a structure-function analysis of the higher-plant ADP-glucose pyrophosphorylase (AGP), we used a random mutagenesis approach in combination with a novel bacterial complementation system to isolate over 100 mutants that were defective in glycogen production. One mutant of the large subunit M27 was identified by its capacity to only partially complement a mutation in the structural gene for the bacterial AGP (glg C), as determined by its light-staining phenotype when cells were exposed to I{sub 2} vapors. Enzyme-linked immunosorbent assay and enzymatic pyrophosphorylysis assays of M27 cell extracts showed that the level of expression and AGP activity was comparable to those of cells that expressed the wildtype recombinant enzyme. Kinetic analysis indicated that the M27 AGP displays normal Michaelis constant values for the substrates glucose-1-phosphate and ATP but requires 6- to 10-fold greater levels of 3-phosphoglycerate (3-PGA) than the wild-type recombinant enzyme for maximum activation. DNA sequence analysis showed that M27 contains a single point mutation that resulted in the replacement of aspartic acid 413 to alanine. Substitution of a lysine residue at this site almost completely abolished activation by 3-PGA. Aspartic acid 413 is adjacent to a lysine residue that was previously identified by chemical modification studies to be important in the binding of 3-PGA. The kinetic properties of M27 corroborate the importance of this region in the allosteric regulation of a higher-plant AGP. 28 refs., 3 figs., 1 tab.

  9. Aspartic acid 413 is important for the normal allosteric functioning of ADP-glucose pyrophosphorylase.

    Science.gov (United States)

    Greene, T W; Woodbury, R L; Okita, T W

    1996-01-01

    As part of a structure-function analysis of the higher-plant ADP-glucose pyrophosphorylase (AGP), we used a random mutagenesis approach in combination with a novel bacterial complementation system to isolate over 100 mutants that were defective in glycogen production (T.W. Greene, S.E. Chantler, M.L. Khan, G.F. Barry, J. Preiss, T.W. Okita [1996] Proc Natl Acad Sci USA 93: 1509-1513). One mutant of the large subunit M27 was identified by its capacity to only partially complement a mutation in the structural gene for the bacterial AGP (glg C), as determined by its light-staining phenotype when cells were exposed to l3 vapors. Enzyme-linked immunosorbent assay and enzymatic pyrophosphorylysis assays of M27 cell extracts showed that the level of expression and AGP activity was comparable to those of cells that expressed the wild-type recombinant enzyme. Kinetic analysis indicated that the M27 AGP displays normal Michaelis constant values for the substrates glucose-1-phosphate and ATP but requires 6- to 10-fold greater levels of 3-phosphoglycerate (3-PGA) than the wild-type recombinant enzyme for maximum activation. DNA sequence analysis showed that M27 contains a single point mutation that resulted in the replacement of aspartic acid 413 to alanine. Substitution of a lysine residue at this site almost completely abolished activation by 3-PGA. Aspartic acid 413 is adjacent to a lysine residue that was previously identified by chemical modification studies to be important in the binding of 3-PGA (K. Ball, J. Preiss [1994] J Biol Chem 269: 24706-24711). The kinetic properties of M27 corroborate the importance of this region in the allosteric regulation of a higher-plant AGP. PMID:8938421

  10. The catalytic role of aspartic acid-92 in a human dual-specific protein-tyrosine-phosphatase.

    Science.gov (United States)

    Denu, J M; Zhou, G; Guo, Y; Dixon, J E

    1995-03-14

    The mechanism of catalysis for the human dual-specific (vaccinia H1-related) protein-tyrosine-phosphatase was investigated. The pH dependence of the kcat value is bell-shaped when p-nitrophenyl phosphate was employed as a model substrate. The kcat/Km pH profile rises with a slope of 2 and decreases with a slope of -1, indicating that two groups must be unprotonated and one group must be protonated for activity. An amino acid residue with an apparent pKa value of 5.5 +/- 0.2 must be unprotonated and a residue with a pKa value of 5.7 must be unprotonated for activity. The pKa value of the catalytic cysteine-124 (C124) was 5.6 +/- 0.1. The aspartic acid-92-asparagine (D92N) mutant enzyme was 100-fold less active than the native enzyme and exhibited the loss of the basic limb in the pH profiles, suggesting that in the native enzyme D92 must be protonated for activity. The D92 residue is conserved throughout the entire family of dual-specific phosphatases. Mutants glutamic acid-6-glutamine, glutamic acid-32-glutamine, aspartic acid-14-asparagine, and aspartic acid-110-asparagine had less than a 2-fold effect on the kinetic parameters when compared to native enzyme. Based upon the lack of a "burst" in rapid reaction kinetics, formation of the intermediate is rate-limiting with both native and D92N mutant enzymes. In agreement with rate-limiting formation of the intermediate, the pKa value of 5.5 for the group which must be unprotonated for activity was assigned to C124.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Chiral Asymmetric Structures in Aspartic Acid and Valine Crystals Assessed by Atomic Force Microscopy.

    Science.gov (United States)

    Teschke, Omar; Soares, David Mendez

    2016-03-29

    Structures of crystallized deposits formed by the molecular self-assembly of aspartic acid and valine on silicon substrates were imaged by atomic force microscopy. Images of d- and l-aspartic acid crystal surfaces showing extended molecularly flat sheets or regions separated by single molecule thick steps are presented. Distinct orientation surfaces were imaged, which, combined with the single molecule step size, defines the geometry of the crystal. However, single molecule step growth also reveals the crystal chirality, i.e., growth orientations. The imaged ordered lattice of aspartic acid (asp) and valine (val) mostly revealed periodicities corresponding to bulk terminations, but a previously unreported molecular hexagonal lattice configuration was observed for both l-asp and l-val but not for d-asp or d-val. Atomic force microscopy can then be used to identify the different chiral forms of aspartic acid and valine crystals.

  12. Aspartic Acid Racemization and Age-Depth Relationships for Organic Carbon in Siberian Permafrost

    Science.gov (United States)

    Brinton, Karen L. F.; Tsapin, Alexandre I.; Gilichinsky, David; McDonald, Gene D.

    2002-03-01

    We have analyzed the degree of racemization of aspartic acid in permafrost samples from Northern Siberia, an area from which microorganisms of apparent ages up to a few million years have previously been isolated and cultured. We find that the extent of aspartic acid racemization in permafrost cores increases very slowly up to an age of ~25,000 years (around 5 m in depth). The apparent temperature of racemization over the age range of 0-25,000 years, determined using measured aspartic acid racemization rate constants, is -19°C. This apparent racemization temperature is significantly lower than the measured environmental temperature (-11 to -13°C) and suggests active recycling of D-aspartic acid in Siberian permafrost up to an age of around 25,000 years. This indicates that permafrost organisms are capable of repairing some molecular damage incurred while in a "dormant" state over geologic time.

  13. L-aspartic acid transport by cat erythrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.W.; Preston, R.L.

    1986-03-01

    Cat and dog red cells are unusual in that they have no Na/K ATPase and contain low K and high Na intracellularly. They also show significant Na dependent L-aspartate (L-asp) transport. The authors have characterized this system in cat RBCs. The influx of /sup 3/H-L-asp (typically 2..mu..M) was measured in washed RBCs incubated for 60 s at 37/sup 0/C in medium containing 140 mM NaCl, 5 mM Kcl, 2 mM CaCl/sub 2/, 15 mM MOPS pH 7.4, 5 mM glucose, and /sup 14/C-PEG as a space marker. The cells were washed 3 times in the medium immediately before incubation which was terminated by centrifuging the RBCs through a layer of dibutylphthalate. Over an L-asp concentration range of 0.5-1000..mu..M, influx obeyed Michaelis-Menten kinetics with a small added linear diffusion component. The Kt and Jmax of the saturable component were 5.40 +/- 0.34 ..mu..M and 148.8 +/- 7.2 ..mu..mol 1. cell/sup -1/h/sup -1/ respectively. Replacement of Na with Li, K, Rb, Cs or choline reduce influx to diffusion. With the addition of asp analogues (4/sup +/M L-asp, 40/sup +/M inhibitor), the following sequence of inhibition was observed (range 80% to 40% inhib.): L-glutamate > L-cysteine sulfonate > D-asp > L-cysteic acid > D-glutamate. Other amino acids such as L-alanine, L-proline, L-lysine, L-cysteine, and taurine showed no inhibition (<5%). These data suggest that cat red cells contain a high-affinity Na dependent transport system for L-asp, glutamate, and closely related analogues which resembles that found in the RBCs of other carnivores and in neural tissues.

  14. The standard enthalpies of formation of crystalline N-(carboxymethyl)aspartic acid and its aqueous solutions

    Science.gov (United States)

    Lytkin, A. I.; Chernyavskaya, N. V.; Volkov, A. V.; Nikol'Skii, V. M.

    2007-07-01

    The energy of combustion of N-(carboxymethyl)aspartic acid (CMAA) was determined by bomb calorimetry in oxygen. The standard enthalpies of combustion and formation of crystalline N-(carboxymethyl)aspartic acid were calculated. The heat effects of solution of crystalline CMAA in water and a solution of sodium hydroxide were measured at 298.15 K by direct calorimetry. The standard enthalpies of formation of CMAA and its dissociation products in aqueous solution were determined.

  15. Immunohistochemical localization of D-β-aspartic acid-containing proteins in pterygium.

    Science.gov (United States)

    Kaji, Yuichi; Oshika, Tetsuro; Nejima, Ryouhei; Mori, Saiyo; Miyata, Kazunori; Fujii, Noriko

    2015-12-10

    Biologically uncommon D-β-aspartic acid (D-β-Asp) residues have been reported to accumulate in organs affected by age-related disorders. In the present study, we investigated the localization of D-β-Asp-containing proteins in cases of pterygium, one of the most prominent age-related ocular conditions. Immunohistochemical localization of D-β-Asp-containing proteins was investigated in surgical specimens of pterygium from 20 patients and control specimens from 10 patients. Strong immunoreactivity to D-β-Asp-containing proteins was observed in subepithelial elastotic lesions and surrounding collagenous lesions from all surgical specimens with pterygia. In contrast, no immunoreactivity to D-β-Asp-containing proteins was seen in pterygium-free specimens. D-β-Asp-containing proteins are produced in organs as they are affected by the aging process. In addition, conversion of L- to D-aspartyl residues is accelerated by ultraviolet (UV) irradiation. Since pterygia can form due to aging or UV exposure, it is reasonable to find D-β-Asp-containing proteins in specimens with pterygia. Furthermore, since D-β-Asp is a non-native amino acid, D-β-Asp-containing proteins may be recognized as allogeneic antigens. Therefore, D-β-Asp-containing proteins in pterygia may responsible for the fibrovascular changes seen in the disorder.

  16. Efficient aspartic acid production by a psychrophile-based simple biocatalyst.

    Science.gov (United States)

    Tajima, Takahisa; Hamada, Mai; Nakashimada, Yutaka; Kato, Junichi

    2015-10-01

    We previously constructed a Psychrophile-based Simple bioCatalyst (PSCat) reaction system, in which psychrophilic metabolic enzymes are inactivated by heat treatment, and used it here to study the conversion of aspartic acid from fumaric acid mediated by the activity of aspartate ammonia-lyase (aspartase). In Escherichia coli, the biosynthesis of aspartic acid competes with that of L-malic acid produced from fumaric acid by fumarase. In this study, E. coli aspartase was expressed in psychrophilic Shewanella livingstonensis Ac10 heat treated at 50 °C for 15 min. The resultant PSCat could convert fumaric acid to aspartic acid without the formation of L-malic acid because of heat inactivation of psychrophilic fumarase activity. Furthermore, alginate-immobilized PSCat produced high yields of aspartic acid and could be re-used nine times. The results of our study suggest that PSCat can be applied in biotechnological production as a new approach to increase the yield of target compounds.

  17. Site-Directed Mutagenesis and Structural Studies Suggest that the Germination Protease, GPR, in Spores of Bacillus Species Is an Atypical Aspartic Acid Protease

    Science.gov (United States)

    Carroll, Thomas M.; Setlow, Peter

    2005-01-01

    Germination protease (GPR) initiates the degradation of small, acid-soluble spore proteins (SASP) during germination of spores of Bacillus and Clostridium species. The GPR amino acid sequence is not homologous to members of the major protease families, and previous work has not identified residues involved in GPR catalysis. The current work has focused on identifying catalytically essential amino acids by mutagenesis of Bacillus megaterium gpr. A residue was selected for alteration if it (i) was conserved among spore-forming bacteria, (ii) was a potential nucleophile, and (iii) had not been ruled out as inessential for catalysis. GPR variants were overexpressed in Escherichia coli, and the active form (P41) was assayed for activity against SASP and the zymogen form (P46) was assayed for the ability to autoprocess to P41. Variants inactive against SASP and unable to autoprocess were analyzed by circular dichroism spectroscopy and multiangle laser light scattering to determine whether the variant's inactivity was due to loss of secondary or quaternary structure, respectively. Variation of D127 and D193, but no other residues, resulted in inactive P46 and P41, while variants of each form were well structured and tetrameric, suggesting that D127 and D193 are essential for activity and autoprocessing. Mapping these two aspartate residues and a highly conserved lysine onto the B. megaterium P46 crystal structure revealed a striking similarity to the catalytic residues and propeptide lysine of aspartic acid proteases. These data indicate that GPR is an atypical aspartic acid protease. PMID:16199582

  18. L-(4-/sup 11/C)aspartic acid: enzymatic synthesis, myocardial uptake, and metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Barrio, J.R.; Egbert, J.E.; Henze, E.; Schelbert, H.R.; Baumgartner, F.J.

    1982-01-01

    Sterile, pyrogen-free L-(4-/sup 11/C)aspartic acid was prepared from /sup 11/CO/sub 2/ using phosphoenolpyruvate carboxylase and glutamic/oxaloacetic acid transaminase immobilized on Sepharose supports to determine if it is a useful indicator for in vivo, noninvasive determination of myocardial metabolism. An intracoronary bolus injection of L-(4-/sup 11/C)aspartic acid into dog myocardium showed a triexponential clearance curve with maximal production of /sup 11/CO/sub 2/ 100 s after injection. Inactivation of myocardial transaminase activity modified the tracer clearance and inhibited the production of /sup 11/CO/sub 2/. Positron-computed tomography imaging showed that the /sup 11/C activities retained in rhesus monkey myocardium are higher than those observed in dog heart after intravenous injection of L-(4-/sup 11/C)aspartic acid. These findings demonstrated the rapid incorporation of the carbon skeleton of L-aspartic acid into the tricarboxylic acid cycle after enzymatic transamination in myocardium and suggested that L-(4-/sup 11/C)aspartic acid could be of value for in vivo, noninvasive assessment of local myocardial metabolism.

  19. Preparation and properties of poly(aspartic acid)-based hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Park, H.D. [Korea Institute of Science and Technology, Seoul (Korea, Republic of); Kim, J.H. [SungKyunKwan University, Suwon (Korea, Republic of); Kim, S.H.; Kim, Y.H. [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    1999-03-01

    High molecular weight polysuccinimide (PSI), as a precursor of poly (aspartic acid), was prepared by thermal polycondensation of L-aspartic acid. The molecular weight was high when phosphoric acid was used as a catalyst, and the ratio to monomer was 0.75 : 1(phosphoric acid : L-aspartic acid). Attempted solution polymerization in various sulfolane/mesitylene mixtures gave only low molecular weight polymers. By the post polymerization of PSI using DCC as a condensing reagent, the molecular weight of PSI could be increased to some extent. Hydrogels was prepared by crosslinking reaction of PSI with diamine, followed by hydrolysis with NaOH either in water or in DMF solution. As high as 104 g water/g-polymer absorption could be obtained from the hydrogel prepared with 3 mol % of hexamethylenediamine. 13 refs., 7 figs., 1 tab.

  20. Biodegradation and Osteosarcoma Cell Cultivation on Poly(aspartic acid) Based Hydrogels.

    Science.gov (United States)

    Juriga, Dávid; Nagy, Krisztina; Jedlovszky-Hajdú, Angéla; Perczel-Kovách, Katalin; Chen, Yong Mei; Varga, Gábor; Zrínyi, Miklós

    2016-09-14

    Development of novel biodegradable and biocompatible scaffold materials with optimal characteristics is important for both preclinical and clinical applications. The aim of the present study was to analyze the biodegradability of poly(aspartic acid)-based hydrogels, and to test their usability as scaffolds for MG-63 osteoblast-like cells. Poly(aspartic acid) was fabricated from poly(succinimide) and hydrogels were prepared using natural amines as cross-linkers (diaminobutane and cystamine). Disulfide bridges were cleaved to thiol groups and the polymer backbone was further modified with RGD sequence. Biodegradability of the hydrogels was evaluated by experiments on the base of enzymes and cell culture medium. Poly(aspartic acid) hydrogels possessing only disulfide bridges as cross-links proved to be degradable by collagenase I. The MG-63 cells showed healthy, fibroblast-like morphology on the double cross-linked and RGD modified hydrogels. Thiolated poly(aspartic acid) based hydrogels provide ideal conditions for adhesion, survival, proliferation, and migration of osteoblast-like cells. The highest viability was found on the thiolated PASP gels while the RGD motif had influence on compacted cluster formation of the cells. These biodegradable and biocompatible poly(aspartic acid)-based hydrogels are promising scaffolds for cell cultivation.

  1. Molecular alteration and carbonization of aspartic acid upon N{sup +} ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Cui, F.Z. E-mail: biomater@mail.tsinghua.edu.cncuifz@sun.ihep.ac.cn; Sun, S.Q.; Zhang, D.M.; Ma, Z.L.; Chen, G.Q

    2000-06-02

    Structural changes of aspartic acid (Asp) irradiated by nitrogen ions of 30 keV were studied using Fourier transform infrared (FTIR) spectroscopy. Significant decreases of the intensities of COO{sup -}, NH{sub 3}{sup +}, COOH and CH{sub 2} vibrations in the FTIR spectra, compared with those of unirradiated Asp, were observed for the sample irradiated at the fluence of 1x10{sup 16} ions/cm{sup 2}. The decrease rates of the intensities of COO{sup -}, NH{sub 3}{sup +}, COOH and CH{sub 2} vibrations with respect to the increasing irradiation fluences up to 4x10{sup 16} ions/cm{sup 2} were different. The results were attributable to the nonstoichiometrical desorption of corresponding volatile species such as H{sub 2}, NH{sub 3}{sup +} and CO{sub 2}. The radiolysis residue of Asp after irradiation at a high fluence of 1x10{sup 17} ions/cm{sup 2} was analyzed and fatty acid was detected.

  2. Juxtamembranous aspartic acid in Insig-1 and Insig-2 is required for cholesterol homeostasis

    Science.gov (United States)

    Gong, Yi; Lee, Joon No; Brown, Michael S.; Goldstein, Joseph L.; Ye, Jin

    2006-01-01

    Insig-1 and Insig-2 are closely related proteins of the endoplasmic reticulum (ER) that mediate feedback control of cholesterol synthesis by sterol-dependent binding to the following two membrane proteins: the escort protein Scap, thus preventing proteolytic processing of sterol regulatory element-binding proteins; and the cholesterol biosynthetic enzyme 3-hydroxy-3-methylglutaryl CoA reductase, thus inducing the ubiquitination and ER-associated degradation of the enzyme. Here, we report that the conserved Asp-205 in Insig-1, which abuts the fourth transmembrane helix at the cytosolic side of the ER membrane, is essential for its dual function. When Asp-205 was mutated to alanine, the mutant Insig-1 lost the ability to bind to Scap and, thus, was unable to suppress the cleavage of sterol regulatory element-binding proteins. The mutant Insig-1 was ineffective also in accelerating sterol-stimulated degradation of 3-hydroxy-3-methylglutaryl CoA reductase. Alanine substitution of the corresponding aspartic acid in Insig-2 produced the same dual defects. These studies identify a single amino acid residue that is crucial for the function of Insig proteins in regulating cholesterol homeostasis in mammalian cells. PMID:16606821

  3. Primary oxidation and reduction products in x-irradiated aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S.M.; Budzinski, E.E.; Box, H.C.

    1976-08-01

    The primary reduction products identified by ESR--ENDOR spectroscopy in single crystals of DL-aspartic acid hydrochloride irradiated at 4.2degreeK are anions formed by addition of an electron to the carbonyl oxygen atoms of the carboxylic acid groups. The main consequence of the oxidation process is to produce a hole centered mainly on atomic chlorine. (AIP)

  4. Reversible receptor methylation is essential for normal chemotaxis of Escherichia coli in gradients of aspartic acid.

    Science.gov (United States)

    Weis, R M; Koshland, D E

    1988-01-01

    The chemotaxis of wild-type cells of Escherichia coli and double mutants lacking the methyltransferase and the methylesterase activities of the receptor modification system has been compared in spatial gradients of aspartic acid. Previous studies showing that a chemotactic response can be observed for the mutant raised questions about the role of methylation in the bacterial memory. To clarify the role of methylation, the redistribution of bacteria in stabilized defined gradients of aspartic acid was monitored by light scattering. There was no redistribution of the mutant cells in nonsaturating gradients of aspartic acid, but over the same range these mutant bacteria were observed to respond and to adapt during tethering experiments. In large saturating gradients of aspartate, slight movement of the mutant up the gradient was observed. These results show that dynamic receptor methylation is required for the chemotactic response to gentle gradients of aspartic acid and that methylation resets to zero and is part of the normal wild-type memory. There are certain gradients, however, in which the methylation-deficient mutants show chemotactic ability, thus explaining the apparent anomaly. Images PMID:2829179

  5. Synthesis of a stable gold hydrosol by the reduction of chloroaurate ions by the amino acid, aspartic acid

    Indian Academy of Sciences (India)

    Saikat Mandal; P R Selvakannan; Sumant Phadtare; Renu Pasricha; Murali Sastry

    2002-10-01

    Development of reliable protocols for the synthesis of nanoparticles of well-defined sizes and good monodispersity is an important aspect of nanotechnology. In this paper, we present details of the synthesis of gold nanoparticles of good monodispersity by the reduction of aqueous chloroaurate ions by the amino acid, aspartic acid. The colloidal gold solution thus formed is extremely stable in time, indicating electrostatic stabilization via nanoparticle surface-bound amino acid molecules. This observation has been used to modulate the size of the gold nanoparticles in solution by varying the molar ratio of chloroaurate ions to aspartic acid in the reaction medium. Characterization of the aspartic acid-reduced gold nanoparticles was carried out by UV-visible spectroscopy, thermogravimetric analysis and transmission electron microscopy. The use of amino acids in the synthesis and stabilization of gold nanoparticle in water has important implications in the development of new protocols for generation of bioconjugate materials.

  6. Aspartic acid in the hippocampus: a biomarker for postoperative cognitive dysfunction

    Science.gov (United States)

    Hu, Rong; Huang, Dong; Tong, Jianbin; Liao, Qin; Hu, Zhonghua; Ouyang, Wen

    2014-01-01

    This study established an aged rat model of cognitive dysfunction using anesthesia with 2% isoflurane and 80% oxygen for 2 hours. Twenty-four hours later, Y-maze test results showed that isoflurane significantly impaired cognitive function in aged rats. Gas chromatography-mass spectrometry results showed that isoflurane also significantly increased the levels of N,N-diethylacetamide, n-ethylacetamide, aspartic acid, malic acid and arabinonic acid in the hippocampus of isoflurane-treated rats. Moreover, aspartic acid, N,N-diethylacetamide, n-ethylacetamide and malic acid concentration was positively correlated with the degree of cognitive dysfunction in the isoflurane-treated rats. It is evident that hippocampal metabolite changes are involved in the formation of cognitive dysfunction after isoflurane anesthesia. To further verify these results, this study cultured hippocampal neurons in vitro, which were then treated with aspartic acid (100 μmol/L). Results suggested that aspartic acid concentration in the hippocampus may be a biomarker for predicting the occurrence and disease progress of cognitive dysfunction. PMID:25206795

  7. Aspartic acid in the hippocampus:a biomarker for postoperative cognitive dysfunction

    Institute of Scientific and Technical Information of China (English)

    Rong Hu; Dong Huang; Jianbin Tong; Qin Liao; Zhonghua Hu; Wen Ouyang

    2014-01-01

    This study established an aged rat model of cognitive dysfunction using anesthesia with 2%iso-lfurane and 80%oxygen for 2 hours. Twenty-four hours later, Y-maze test results showed that isoflurane significantly impaired cognitive function in aged rats. Gas chromatography-mass spectrometry results showed that isolfurane also signiifcantly increased the levels of N,N-diethy-lacetamide, n-ethylacetamide, aspartic acid, malic acid and arabinonic acid in the hippocampus of isolfurane-treated rats. Moreover, aspartic acid, N,N-diethylacetamide, n-ethylacetamide and malic acid concentration was positively correlated with the degree of cognitive dysfunction in the isolfurane-treated rats. It is evident that hippocampal metabolite changes are involved in the formation of cognitive dysfunction after isoflurane anesthesia. To further verify these results, this study cultured hippocampal neurons in vitro, which were then treated with aspartic acid (100 µmol/L). Results suggested that aspartic acid concentration in the hippocampus may be a biomarker for predicting the occurrence and disease progress of cognitive dysfunction.

  8. Alleviation of Seawater Stress on Tomato by Foliar Application of Aspartic Acid and Glutathione

    Directory of Open Access Journals (Sweden)

    Samia Ageeb Akladious

    2013-08-01

    Full Text Available A pot experiment was carried out in the botanical garden of Faculty of Education, Ain Shams University, with the aim of studying the effect of salinity levels (4, 8 and 16% of diluted seawater and foliar application of aspartic acid and/or glutathione on the growth and chemical constituents of tomatoes (lycopersicon esculentum Mill plants. The most important results can be summarized as: 1. Treatments of high salinity levels reduced all growth parameters and chemical constituents of plants. 2 Both aspartic acid and glutathione significantly increased plant growth, the contents of anthocyanin, α-tocopherol, ascorbic acid and enzymatic activities. In addition, the content of endogenous amino acids was increased which in turn led to positive changes in the picture of protein electrophoresis, theses changes were accompanied by appearance and disappearance of some protein bands and caused obvious changes in the anatomical features of the stems. 3 The effect of aspartic acid was superior to that of glutathione on increasing plant growth and chemical constituents. 4 Under low saline conditions, the maximum plant growth for all the recorded growth parameters was obtained from plants treated with aspartic acid and grown under 8% of seawater, followed by 4%. However, glutathione had inhibitor effect on plant growth and chemical constituents of plants grown at 16% seawater. The data revealed that the different antioxidants could partially alleviate the harmful effects of salinity stress that reflected on growth and some physiological changes of tomato plant.

  9. Accumulation of aspartic acid421- and glutamic acid391-cleaved tau in neurofibrillary tangles correlates with progression in Alzheimer disease.

    Science.gov (United States)

    Basurto-Islas, Gustavo; Luna-Muñoz, Jose; Guillozet-Bongaarts, Angela L; Binder, Lester I; Mena, Raul; García-Sierra, Francisco

    2008-05-01

    Truncations of tau protein at aspartic acid421 (D421) and glutamic acid391 (E391) residues are associated with neurofibrillary tangles (NFTs) in the brains of Alzheimer disease (AD) patients. Using immunohistochemistry with antibodies to D421- and E391-truncated tau (Tau-C3 and MN423, respectively), we correlated the presence of NFTs composed of these truncated tau proteins with clinical and neuropathologic parameters in 17 AD and 23 non-AD control brains. The densities of NFTs composed of D421- or E391-truncated tau correlated with clinical dementia index and Braak staging in AD. Glutamic acid391 tau truncation was prominent in the entorhinal cortex, whereas D421 truncation was prominent in the subiculum, suggesting that NFTs composed of either D421- or E391-truncated tau may be formed mutually exclusively in these areas. Both truncations were associated with the prevalence of the apolipoprotein E epsilon4 allele. By double labeling, intact tau in NFTs was commonly associated with D421-cleaved tau but not with E391-truncated tau; D421-cleaved tau was never associated with E391-truncated tau. These results indicate that tau is not randomly proteolyzed at different domains, and that proteolysis occurs sequentially from the C-terminus to inner regions of tau in AD progression. Identification of NFTs composed of tau at different stages of truncation may facilitate assessment of neurofibrillary pathology in AD.

  10. Predicting Three-Dimensional Conformations of Peptides Constructed of Only Glycine, Alanine, Aspartic Acid, and Valine

    Science.gov (United States)

    Oda, Akifumi; Fukuyoshi, Shuichi

    2015-06-01

    The GADV hypothesis is a form of the protein world hypothesis, which suggests that life originated from proteins (Lacey et al. 1999; Ikehara 2002; Andras 2006). In the GADV hypothesis, life is thought to have originated from primitive proteins constructed of only glycine, alanine, aspartic acid, and valine ([GADV]-proteins). In this study, the three-dimensional (3D) conformations of randomly generated short [GADV]-peptides were computationally investigated using replica-exchange molecular dynamics (REMD) simulations (Sugita and Okamoto 1999). Because the peptides used in this study consisted of only 20 residues each, they could not form certain 3D structures. However, the conformational tendencies of the peptides were elucidated by analyzing the conformational ensembles generated by REMD simulations. The results indicate that secondary structures can be formed in several randomly generated [GADV]-peptides. A long helical structure was found in one of the hydrophobic peptides, supporting the conjecture of the GADV hypothesis that many peptides aggregated to form peptide multimers with enzymatic activity in the primordial soup. In addition, these results indicate that REMD simulations can be used for the structural investigation of short peptides.

  11. Poly(aspartic acid) with adjustable pH-dependent solubility.

    Science.gov (United States)

    Németh, Csaba; Gyarmati, Benjámin; Abdullin, Timur; László, Krisztina; Szilágyi, András

    2017-02-01

    Poly(aspartic acid) (PASP) derivatives with adjustable pH-dependent solubility were synthesized and characterized to establish the relationship between their structure and solubility in order to predict their applicability as a basic material for enteric coatings. Polysuccinimide, the precursor of PASP, was modified with short chain alkylamines, and the residual succinimide rings were subsequently opened to prepare the corresponding PASP derivatives. Study of the effect of the type and concentration of the side groups on the pH-dependent solubility of PASP showed that solubility can be adjusted by proper selection of the chemical structure. The Henderson-Hasselbalch (HH) and the extended HH equations were used to describe the pH-dependent solubility of the polymers quantitatively. The estimate provided by the HH equation is poor, but an accurate description of the pH-dependent solubility can be found with the extended HH equation. The dissolution rate of a polymer film prepared from a selected PASP derivative was determined by fluorescence marking. The film dissolved rapidly when the pH was increased above its pKa. Cellular viability tests show that PASP derivatives are non-toxic to a human cell line. These polymers are thus of great interest as starting materials for enteric coatings.

  12. Predicting three-dimensional conformations of peptides constructed of only glycine, alanine, aspartic acid, and valine.

    Science.gov (United States)

    Oda, Akifumi; Fukuyoshi, Shuichi

    2015-06-01

    The GADV hypothesis is a form of the protein world hypothesis, which suggests that life originated from proteins (Lacey et al. 1999; Ikehara 2002; Andras 2006). In the GADV hypothesis, life is thought to have originated from primitive proteins constructed of only glycine, alanine, aspartic acid, and valine ([GADV]-proteins). In this study, the three-dimensional (3D) conformations of randomly generated short [GADV]-peptides were computationally investigated using replica-exchange molecular dynamics (REMD) simulations (Sugita and Okamoto 1999). Because the peptides used in this study consisted of only 20 residues each, they could not form certain 3D structures. However, the conformational tendencies of the peptides were elucidated by analyzing the conformational ensembles generated by REMD simulations. The results indicate that secondary structures can be formed in several randomly generated [GADV]-peptides. A long helical structure was found in one of the hydrophobic peptides, supporting the conjecture of the GADV hypothesis that many peptides aggregated to form peptide multimers with enzymatic activity in the primordial soup. In addition, these results indicate that REMD simulations can be used for the structural investigation of short peptides.

  13. Does Aspartic Acid Racemization Constrain the Depth Limit of the Subsurface Biosphere?

    Science.gov (United States)

    Onstott, T C.; Magnabosco, C.; Aubrey, A. D.; Burton, A. S.; Dworkin, J. P.; Elsila, J. E.; Grunsfeld, S.; Cao, B. H.; Hein, J. E.; Glavin, D. P.; Kieft, T. L.; Silver, B. J.; Phelps, T. J.; Heerden, E. Van; Opperman, D. J.; Bada, J. L.

    2013-01-01

    Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of approximately 89 years for 1 km depth and 27 C and 1-2 years for 3 km depth and 54 C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples.

  14. Does aspartic acid racemization constrain the depth limit of the subsurface biosphere?

    Energy Technology Data Exchange (ETDEWEB)

    Onstott, T. C. [Princeton University; Aubrey, A.D. [Jet Propulsion Laboratory, Pasadena, CA; Kieft, T L [New Mexico Institute of Mining and Technology; Silver, B J [Jet Propulsion Laboratory, Pasadena, CA; Phelps, Tommy Joe [ORNL; Van Heerden, E. [University of the Free State; Opperman, D. J. [University of the Free State; Bada, J L. [Geosciences Research Division, Scripps Instition of Oceanography, Univesity of California San Diego,

    2014-01-01

    Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of ~89 years for 1 km depth and 27 C and 1 2 years for 3 km depth and 54 C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples.

  15. Does aspartic acid racemization constrain the depth limit of the subsurface biosphere?

    Science.gov (United States)

    Onstott, T C; Magnabosco, C; Aubrey, A D; Burton, A S; Dworkin, J P; Elsila, J E; Grunsfeld, S; Cao, B H; Hein, J E; Glavin, D P; Kieft, T L; Silver, B J; Phelps, T J; van Heerden, E; Opperman, D J; Bada, J L

    2014-01-01

    Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of ~89 years for 1 km depth and 27 °C and 1-2 years for 3 km depth and 54 °C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 °C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples.

  16. Studies on the metabolism of beta-hydroxy- aspartic acid

    Directory of Open Access Journals (Sweden)

    Ikegami,Takuma

    1975-08-01

    Full Text Available The content of beta-hydroxyaspartic acid was measured in the urine of man and several species of animals. The configuration of urinary beta-hydroxyaspartic acid was deduced to be L-erythro in form by chromatographic comparisons with authentic samples. An increased excretion of urinary beta-hydroxyaspartic acid was observed in cats when serine or thiamine was administered with glycine. Glycine-1-14C administered to rats was incorporated into the urinary beta-hydroxyaspartic acid. The formation of beta-hydroxyaspartic acid in pig-liver homogenate increased in the presence of glutamate and thiamine pyrophosphate. These results were discussed in relation to the author's working hypothesis on the biosynthesis of beta-hydroxyaspartic acid.

  17. Changes in D-aspartic acid and D-glutamic acid levels in the tissues and physiological fluids of mice with various D-aspartate oxidase activities.

    Science.gov (United States)

    Han, Hai; Miyoshi, Yurika; Koga, Reiko; Mita, Masashi; Konno, Ryuichi; Hamase, Kenji

    2015-12-10

    D-Aspartic acid (D-Asp) and D-glutamic acid (D-Glu) are currently paid attention as modulators of neuronal transmission and hormonal secretion. These two D-amino acids are metabolized only by D-aspartate oxidase (DDO) in mammals. Therefore, in order to design and develop new drugs controlling the D-Asp and D-Glu amounts via regulation of the DDO activities, changes in these acidic D-amino acid amounts in various tissues are expected to be clarified in model animals having various DDO activities. In the present study, the amounts of Asp and Glu enantiomers in 6 brain tissues, 11 peripheral tissues and 2 physiological fluids of DDO(+/+), DDO(+/-) and DDO(-/-) mice were determined using a sensitive and selective two-dimensional HPLC system. As a result, the amounts of D-Asp were drastically increased with the decrease in the DDO activity in all the tested tissues and physiological fluids. On the other hand, the amounts of D-Glu were almost the same among the 3 strains of mice. The present results are useful for designing new drug candidates, such as DDO inhibitors, and further studies are expected.

  18. Racemization of aspartic acid and phenylalanine in the sweetener aspartame at 100 degrees C.

    Science.gov (United States)

    Boehm, M F; Bada, J L

    1984-01-01

    The racemization half-lives (i.e., the time required to reach a D/L = 0.33) at pH 6.8 for aspartic acid and phenylalanine in the sweetener aspartame (L-aspartyl-L-phenylalanine methyl ester) were determined to be 13 and 23 hours, respectively, at 100 degrees C. Racemization at this pH does not occur in aspartame but rather in its diketopiperazine decomposition product. Our results indicate that the use of aspartame to sweeten neutral pH foods and beverages that are then heated at elevated temperature could generate D-aspartic acid and D-phenylalanine. The nutritive consequences of these D-amino acids in the human diet are not well established, and thus aspartame should probably not be used as a sweetener when the exposure of neutral pH foods and beverages to elevated temperatures is required. At pH 4, a typical pH of most foods and beverages that might be sweetened with aspartame, the half-lives are 47 hours for aspartic acid and 1200 hours for phenylalanine at 100 degrees C. Racemization at pH 4 takes place in aspartame itself. Although the racemization rates at pH 4 are slow and no appreciable racemization of aspartic acid and phenylalanine should occur during the normal use of aspartame, some food and beverage components could conceivably act as catalysts. Additional studies are required to evaluate whether the use of aspartame as a sugar substitute might not in turn result in an increased human consumption of D-aspartic acid and D-phenylalanine. PMID:6591191

  19. Estimation of paleotemperature from racemization of aspartic acid in combination with radiocarbon age

    Science.gov (United States)

    Minami, Masayo; Takeyama, Masami; Mimura, Koichi; Nakamura, Toshio

    2007-06-01

    We tried to estimate paleotemperatures from two chosen fossils by measuring D/L aspartic acid ratios and radiocarbon ages of the XAD-2-treated hydrolysate fractions in the fossils. The D/L aspartic acid ratio was measured with a gas chromatograph and radiocarbon dating was performed using a Tandetron AMS system at Nagoya University. The radiocarbon age of a fossil mammoth molar collected from Bykovsky Peninsula, eastern Siberia, was found to be 35,170 ± 300 BP as an average value for the XAD-treated hydrolysate fractions. The aspartic acid in the mammoth molar showed a little evidence of racemization, which might be due to in vivo racemization during the lifetime and then suggests negligible or no postmortem racemization during burial in permafrost. From four animal bone fossils collected from a shell mound excavated at the Awazu submarine archeological site in Lake Biwa, Shiga, Japan, the racemization-based effective mean temperature was calculated to be 15-16 °C using the D/L aspartic acid ratio of about 0.11 and the 14C age of 4500 BP for the XAD-2-treated hydrolysate fractions in the fossils. The average annual temperature was estimated to be 11-12 °C, which approximates to the temperature that the fossils experienced during burial at the site. Although the application of racemization ratios in fossils as paleotemperature indicators is surrounded with many difficulties, the results obtained in this study suggest its feasibility.

  20. The heat effects of dissociation of N-(carboxymethyl)aspartic acid

    Science.gov (United States)

    Lytkin, A. I.; Chernyavskaya, N. V.; Orlova, T. D.; Nikol'Skii, V. M.

    2009-07-01

    The heat effects of dissociation of N-(carboxymethyl)aspartic acid were determined calorimetrically at 298.15 K and various ionic strength values. The standard thermodynamic characteristics of dissociation of the complexone at fixed and zero ionic strengths were calculated.

  1. Estimation of paleotemperature from racemization of aspartic acid in combination with radiocarbon age

    Energy Technology Data Exchange (ETDEWEB)

    Minami, Masayo [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan)]. E-mail: minami@nendai.nagoya-u.ac.jp; Takeyama, Masami [Department of Earth and Planetary Sciences, School of Science, Nagoya 464-8602 (Japan); Mimura, Koichi [Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602 (Japan); Nakamura, Toshio [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan)

    2007-06-15

    We tried to estimate paleotemperatures from two chosen fossils by measuring D/L aspartic acid ratios and radiocarbon ages of the XAD-2-treated hydrolysate fractions in the fossils. The D/L aspartic acid ratio was measured with a gas chromatograph and radiocarbon dating was performed using a Tandetron AMS system at Nagoya University. The radiocarbon age of a fossil mammoth molar collected from Bykovsky Peninsula, eastern Siberia, was found to be 35,170 {+-} 300 BP as an average value for the XAD-treated hydrolysate fractions. The aspartic acid in the mammoth molar showed a little evidence of racemization, which might be due to in vivo racemization during the lifetime and then suggests negligible or no postmortem racemization during burial in permafrost. From four animal bone fossils collected from a shell mound excavated at the Awazu submarine archeological site in Lake Biwa, Shiga, Japan, the racemization-based effective mean temperature was calculated to be 15-16 deg. C using the D/L aspartic acid ratio of about 0.11 and the {sup 14}C age of 4500 BP for the XAD-2-treated hydrolysate fractions in the fossils. The average annual temperature was estimated to be 11-12 deg. C, which approximates to the temperature that the fossils experienced during burial at the site. Although the application of racemization ratios in fossils as paleotemperature indicators is surrounded with many difficulties, the results obtained in this study suggest its feasibility.

  2. A Green Polymerization of Aspartic Acid for the Undergraduate Organic Laboratory

    Science.gov (United States)

    Bennett, George D.

    2005-01-01

    The green polymerization of aspartic acid carried out during an organic-inorganic synthesis laboratory course for undergraduate students is described. The procedure is based on work by Donlar Corporation, a Peru, Illinois-based company that won a Green Chemistry Challenge Award in 1996 in the Small Business category for preparing thermal…

  3. N-Hydroxypyrazolyl glycine derivatives as selective N-methyl-D-aspartic acid receptor ligands

    DEFF Research Database (Denmark)

    Clausen, Rasmus Prætorius; Christensen, Caspar; Hansen, Kasper Bø;

    2008-01-01

    A series of analogues based on N-hydroxypyrazole as a bioisostere for the distal carboxylate group of aspartate have been designed, synthesized, and pharmacologically characterized. Affinity studies on the major glutamate receptor subgroups show that these 4-substituted N-hydroxypyrazol-5-yl...... glycine (NHP5G) derivatives are selectively recognized by N-methyl- d-aspartic acid (NMDA) receptors and that the ( R)-enantiomers are preferred. Moreover, several of the compounds are able to discriminate between individual subtypes among the NMDA receptors, providing new pharmacological tools...

  4. N-(Fluoren-9-ylmethoxycarbonyl-l-aspartic acid 4-tert-butyl ester

    Directory of Open Access Journals (Sweden)

    Kazuhiko Yamada

    2009-11-01

    Full Text Available The bond distances and bond angles of the title compound, C23H25NO6, are consistent with values typically found for fluoren-9-ylmethoxycarbonyl-protected amino acids. The conformations of the backbone and the side chain are slightly different from those of l-aspartic acid. The crystal structure exhibits two intermolecular hydrogen bonds, forming a two-dimensional sheet structure parallel to the ab plane.

  5. Observation of the side chain O-methylation of glutamic acid or aspartic acid containing model peptides by electrospray ionization-mass spectrometry.

    Science.gov (United States)

    Atik, A Emin; Guray, Melda Z; Yalcin, Talat

    2017-03-15

    O-methylation of the side chains of glutamic acid (E) and aspartic acid (D) residues is generally observed modification when an acidified methanol/water (MeOH/dH2O) mixture is used as a solvent system during sample preparation for proteomic research. This chemical modification may result misidentification with endogenous protein methylation; therefore, a special care should be taken during sample handling prior to mass spectrometric analysis. In the current study, we systematically examined the extent of E/D methylation and C-terminus carboxyl group of synthetic model peptides in terms of different incubation temperatures, storage times, and added acid types as well as its percentages. To monitor these effects, C-terminus amidated and free acid forms of synthetic model peptides comprised of E or D residue(s) have been analyzed by electrospray ionization-mass spectrometry (ESI-MS). Additionally, LC-MS/MS experiments were performed to confirm the formation of methylated peptide product. The results showed that the rate of methylation was increased as the temperature increases along with prolong incubation times. Moreover, the extent of methylation was remarkably high when formic acid (FA) used as a protonation agent instead of acetic acid (AA). In addition, it was found that the degree of methylation was significantly decreased by lowering acid percentages in ESI solution. More than one acidic residue containing model peptides have been also used to explore the extent of multiple methylation reaction. Lastly, the ethanol (EtOH) and isopropanol (iPrOH) have been substituted separately with MeOH in sample preparation step to investigate the extent of esterification reaction under the same experimental conditions. However, in the positive perspective of view, this method can be used as a simple, rapid and cheap method for methylation of acidic residues under normal laboratory conditions.

  6. Transport of Arginine and Aspartic Acid into Isolated Barley Mesophyll Vacuoles 1

    Science.gov (United States)

    Martinoia, Enrico; Thume, Monika; Vogt, Esther; Rentsch, Doris; Dietz, Karl-Josef

    1991-01-01

    The transport of arginine into isolated barley (Hordeum vulgare L.) mesophyll vacuoles was investigated. In the absence of ATP, arginine uptake was saturable with a Km of 0.3 to 0.4 millimolar. Positively charged amino acids inhibited arginine uptake, lysine being most potent with a Ki of 1.2 millimolar. In the presence of free ATP, but not of its Mg-complex, uptake of arginine was drastically enhanced and a linear function of its concentration up to 16 millimolar. The nonhydrolyzable adenylyl imidodiphosphate, but no other nucleotide tested, could substitute for ATP. Therefore, it is suggested that this process does not require energy and does not involve the tonoplast ATPase. The ATP-dependent arginine uptake was strongly inhibited by p-chloromercuriphenylsulfonic acid. Furthermore, hydrophobic amino acids were inhibitory (I50 phenylalanine 1 millimolar). Similar characteristics were observed for the uptake of aspartic acid. However, rates of ATP-stimulated aspartic acid transport were 10-fold lower as compared to arginine transport. Uptake of aspartate in the absence of ATP was negligible. PMID:16668447

  7. Absorption and utilization of organic matter by the strict autotroph, Thiobacillus thiooxidans, with special reference to aspartic acid.

    Science.gov (United States)

    Butler, R G; Umbreit, W W

    1966-02-01

    Butler, Richard G. (Rutgers, The State University, New Brunswick, N.J.), and Wayne W. Umbreit. Absorption and utilization of organic matter by the strict autotroph, Thiobacillus thiooxidans, with special reference to aspartic acid. J. Bacteriol. 91:661-666. 1966.-The strictly autotrophic bacterium, Thiobacillus thiooxidans, can be shown to assimilate a variety of organic materials. Aspartic acid can be assimilated into protein and can be converted into CO(2), but even in the presence of sulfur it cannot serve as the sole source of carbon for growth. The reason appears to be that aspartic acid is converted into inhibitory materials.

  8. Anharmonic vibrational studies of L-aspartic acid using HF and DFT calculations

    Science.gov (United States)

    Alam, Mohammad Jane; Ahmad, Shabbir

    2012-10-01

    The experimental and theoretical studies on the structure, molecular properties and vibrational spectra of L-aspartic acid are presented. The molecular structure, harmonic and anharmonic vibrational frequencies, molecular properties, MEP mapping, NBO analysis and electronic spectra of L-aspartic acid have been reported. Computed geometrical parameters and anharmonic frequencies of fundamental, combination and overtone transitions were found in satisfactory agreement with the experimental data. The UV-Vis spectrum of present molecule has been recorded and the electronic properties such as HOMO and LUMO energies and few low lying excited states were carried out by using time dependent density functional theory (TD-DFT) approach. Natural Bond Orbital (NBO) analysis has been performed for analyzing charge delocalization throughout the molecule. Molecular electrostatic potential map has also been used for quantitative measure of the chemical activities of various sites of the molecule.

  9. Surface proton transport of fully protonated poly(aspartic acid) thin films on quartz substrates

    Science.gov (United States)

    Nagao, Yuki; Kubo, Takahiro

    2014-12-01

    Thin film structure and the proton transport property of fully protonated poly(aspartic acid) (P-Asp100) have been investigated. An earlier study assessed partially protonated poly(aspartic acid), highly oriented thin film structure and enhancement of the internal proton transport. In this study of P-Asp100, IR p-polarized multiple-angle incidence resolution (P-MAIR) spectra were measured to investigate the thin film structure. The obtained thin films, with thicknesses of 120-670 nm, had no oriented structure. Relative humidity dependence of the resistance, proton conductivity, and normalized resistance were examined to ascertain the proton transport property of P-Asp100 thin films. The obtained data showed that the proton transport of P-Asp100 thin films might occur on the surface, not inside of the thin film. This phenomenon might be related with the proton transport of the biological system.

  10. Age determination of marine sediments in the western North Pacific by aspartic acid chronology

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Naomi; Kusakabe, Masashi [Japan Marine Science and Technology Center, Yokosuka, Kanagawa (Japan); Handa, Nobuhiko; Oba, Tadamichi; Matsuoka, Hiromi; Kimoto, Katsunori

    1997-02-01

    The ages of fossil planktonic foraminifera, Pulleniatina obliquiloculata, in sediments (core 3bPC) from the western North Pacific were determined by aspartic acid chronology, which uses the racemization reaction rate constant of aspartic acid (k{sub Asp}). Aspartic acid racemization-based ages (Asp ages) ranged from 7,600 yrBP at the surface, to 307,000 yrBP at a depth of 352.9 cm in the sediments. This sediment core was also dated by the glacial-interglacial fluctuation of {sigma}{sup 18}O chronology, and the ages determined by both chronologies were compared. The ages derived from aspartic acid chronology and {sigma}{sup 18}O stratigraphy were more or less consistent, but there appeared to be some differences in age estimates between these two dating methods at some depths within the core. In the core top sediments, the likely cause for the age discrepancy could be the loss of the surface sediment during sampling of the core. At depths of 66.3 and 139 cm within the core, Asp ages indicated reduced sedimentation rates during ca. 60,000-80,000 yrBP and ca. 140,000-190,000 yrBP. The maximum age differences in both chronologies are 33,000 yr and 46,600 yr during each of these periods. These anomalous reductions in sedimentation rates occurring during these periods could possibly be related to some geological events, such as an increased dissolution effect of the calcium carbonate in the western North Pacific. Another possible reason for these age differences could be the unreliability in {sigma}{sup 18}O ages of core 3bPC as they were estimated by {sigma}{sup 18}O ages of another core, 3aPC. (author)

  11. Age estimation in forensic sciences: Application of combined aspartic acid racemization and radiocarbon analysis

    Energy Technology Data Exchange (ETDEWEB)

    Alkass, K; Buchholz, B A; Ohtani, S; Yamamoto, T; Druid, H; Spalding, S L

    2009-11-02

    Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster, since the age at death, birth date and year of death, as well as gender, can guide investigators to the correct identity among a large number of possible matches. Traditional morphological methods used by anthropologists to determine age are often imprecise, whereas chemical analysis of tooth dentin, such as aspartic acid racemization has shown reproducible and more precise results. In this paper we analyze teeth from Swedish individuals using both aspartic acid racemization and radiocarbon methodologies. The rationale behind using radiocarbon analysis is that above-ground testing of nuclear weapons during the cold war (1955-1963) caused an extreme increase in global levels of carbon-14 ({sup 14}C) which have been carefully recorded over time. Forty-four teeth from 41 individuals were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel and ten of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R2=0.66, p < 0.05). Radiocarbon analysis showed an excellent precision with an overall absolute error of 0.6 {+-} 04 years. Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 {+-} 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of death. We show how these methods in combination can also assist in the estimation of date of death of an unidentified victim. This strategy can be of significant assistance in forensic casework involving dead victim identification.

  12. Surface proton transport of fully protonated poly(aspartic acid) thin films on quartz substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yuki, E-mail: ynagao@jaist.ac.jp; Kubo, Takahiro

    2014-12-30

    Graphical abstract: - Highlights: • Proton transport of fully protonated poly(aspartic acid) thin film was investigated. • The thin film structure differed greatly from the partially protonated one. • Proton transport occurs on the surface, not inside of the thin film. • This result contributes to biological transport systems such as bacteriorhodopsin. - Abstract: Thin film structure and the proton transport property of fully protonated poly(aspartic acid) (P-Asp100) have been investigated. An earlier study assessed partially protonated poly(aspartic acid), highly oriented thin film structure and enhancement of the internal proton transport. In this study of P-Asp100, IR p-polarized multiple-angle incidence resolution (P-MAIR) spectra were measured to investigate the thin film structure. The obtained thin films, with thicknesses of 120–670 nm, had no oriented structure. Relative humidity dependence of the resistance, proton conductivity, and normalized resistance were examined to ascertain the proton transport property of P-Asp100 thin films. The obtained data showed that the proton transport of P-Asp100 thin films might occur on the surface, not inside of the thin film. This phenomenon might be related with the proton transport of the biological system.

  13. Platinum-Incorporating Poly(N-vinylpyrrolidone)-poly(aspartic acid) Pseudoblock Copolymer Nanoparticles for Drug Delivery.

    Science.gov (United States)

    Yao, Xikuang; Xie, Chen; Chen, Weizhi; Yang, Chenchen; Wu, Wei; Jiang, Xiqun

    2015-07-13

    Cisplatin-incorporating pseudoblock copolymer nanoparticles with high drug loading efficiency (ca. 50%) were prepared built on host-guest inclusion complexation between β-cyclodextrin end-capped poly(N-vinylpyrrolidone) block and admantyl end-capped poly(aspartic acid) block, followed by the coordination between cisplatin and carboxyl groups in poly(aspartic acid). The host-guest interaction between the two polymer blocks was examined by two-dimensional nuclear overhauser effect spectroscopy. The size and morphology of nanoparticles formed were characterized by dynamic light scattering, zeta potential, transmission electron microscopy, and atomic force microscopy. The size control of nanoparticles was carried out by varying the ratio of poly(N-vinylpyrrolidone) to poly(aspartic acid). The nanoparticles were stable in the aqueous medium with different pH values but disintegrated in the medium containing Cl(-) ions. The in vitro and in vivo antitumor effects of cisplatin-loaded nanoparticles were evaluated. The biodistribution of the nanoparticles in vivo was studied by noninvasive near-infrared fluorescence imaging and ion-coupled plasma mass spectrometry. It was found that cisplatin-loaded nanoparticles could effectively accumulate in the tumor site and exhibited significant superior in vivo antitumor activity to the commercially available free cisplatin by combining the tumor volume, body weight, and survival rate measurements.

  14. Estimation of age at death based on aspartic acid racemization in elastic cartilage of the epiglottis.

    Science.gov (United States)

    Matzenauer, Christian; Reckert, Alexandra; Ritz-Timme, Stefanie

    2014-11-01

    Age estimation based on aspartic acid racemization (AAR) has been applied successfully to various tissues. For routine uses, AAR is analyzed in dentine. For cases in which teeth are unavailable, analyzing AAR in purified elastin has been shown to be an alternative method. The suitability of elastic cartilage from the epiglottis as an elastin source for age estimation based on AAR was tested. A total of 65 tissue samples (cartilage) of epiglottis and 45 samples of elastin purified from the elastic cartilage of epiglottis samples were analyzed. While the D-aspartic acid content of total tissue samples increased with age only slowly, its increase with age in purified elastin samples was similar to that in purified elastin from other tissues. The relationship between the D-aspartic acid content and age was shown to be close enough for age estimation based on AAR in purified elastin from the elastic cartilage of the epiglottis, provided a sufficient quality of elastin purification. Age estimation based on AAR in purified elastin from the epiglottis might serve as a valuable alternative in cases in which other tissues (e.g., teeth) are unavailable.

  15. Structural and Functional Importance of Transmembrane Domain 3 (TM3) in the Aspartate:Alanine Antiporter AspT: Topology and Function of the Residues of TM3 and Oligomerization of AspT▿

    Science.gov (United States)

    Nanatani, Kei; Maloney, Peter C.; Abe, Keietsu

    2009-01-01

    AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, a membrane protein of 543 amino acids with 10 putative transmembrane (TM) helices, is the prototype of the aspartate:alanine exchanger (AAE) family of transporters. Because TM3 (isoleucine 64 to methionine 85) has many amino acid residues that are conserved among members of the AAE family and because TM3 contains two charged residues and four polar residues, it is thought to be located near (or to form part of) the substrate translocation pathway that includes the binding site for the substrates. To elucidate the role of TM3 in the transport process, we carried out cysteine-scanning mutagenesis. The substitutions of tyrosine 75 and serine 84 had the strongest inhibitory effects on transport (initial rates of l-aspartate transport were below 15% of the rate for cysteine-less AspT). Considerable but less-marked effects were observed upon the replacement of methionine 70, phenylalanine 71, glycine 74, arginine 76, serine 83, and methionine 85 (initial rates between 15% and 30% of the rate for cysteine-less AspT). Introduced cysteine residues at the cytoplasmic half of TM3 could be labeled with Oregon green maleimide (OGM), whereas cysteines close to the periplasmic half (residues 64 to 75) were not labeled. These results suggest that TM3 has a hydrophobic core on the periplasmic half and that hydrophilic residues on the cytoplasmic half of TM3 participate in the formation of an aqueous cavity in membranes. Furthermore, the presence of l-aspartate protected the cysteine introduced at glycine 62 against a reaction with OGM. In contrast, l-aspartate stimulated the reactivity of the cysteine introduced at proline 79 with OGM. These results demonstrate that TM3 undergoes l-aspartate-induced conformational alterations. In addition, nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses and a glutaraldehyde cross-linking assay suggest that functional AspT forms homo-oligomers as a

  16. Structural and functional importance of transmembrane domain 3 (TM3) in the aspartate:alanine antiporter AspT: topology and function of the residues of TM3 and oligomerization of AspT.

    Science.gov (United States)

    Nanatani, Kei; Maloney, Peter C; Abe, Keietsu

    2009-04-01

    AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, a membrane protein of 543 amino acids with 10 putative transmembrane (TM) helices, is the prototype of the aspartate:alanine exchanger (AAE) family of transporters. Because TM3 (isoleucine 64 to methionine 85) has many amino acid residues that are conserved among members of the AAE family and because TM3 contains two charged residues and four polar residues, it is thought to be located near (or to form part of) the substrate translocation pathway that includes the binding site for the substrates. To elucidate the role of TM3 in the transport process, we carried out cysteine-scanning mutagenesis. The substitutions of tyrosine 75 and serine 84 had the strongest inhibitory effects on transport (initial rates of l-aspartate transport were below 15% of the rate for cysteine-less AspT). Considerable but less-marked effects were observed upon the replacement of methionine 70, phenylalanine 71, glycine 74, arginine 76, serine 83, and methionine 85 (initial rates between 15% and 30% of the rate for cysteine-less AspT). Introduced cysteine residues at the cytoplasmic half of TM3 could be labeled with Oregon green maleimide (OGM), whereas cysteines close to the periplasmic half (residues 64 to 75) were not labeled. These results suggest that TM3 has a hydrophobic core on the periplasmic half and that hydrophilic residues on the cytoplasmic half of TM3 participate in the formation of an aqueous cavity in membranes. Furthermore, the presence of l-aspartate protected the cysteine introduced at glycine 62 against a reaction with OGM. In contrast, l-aspartate stimulated the reactivity of the cysteine introduced at proline 79 with OGM. These results demonstrate that TM3 undergoes l-aspartate-induced conformational alterations. In addition, nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses and a glutaraldehyde cross-linking assay suggest that functional AspT forms homo-oligomers as a

  17. Comparison of immobilized poly-L-aspartic acid and poly-L-glutamic acid for chelation of metal cations

    Energy Technology Data Exchange (ETDEWEB)

    Malachowski, Lisa; Holcombe, James A

    2004-07-26

    Poly-L-aspartic acid (PLAsp) and poly-L-glutamic acid (PLGlu) were individually immobilized onto controlled pore glass (CPG) and compared according to their metal-binding capabilities in a solution of pH 7.0. The metal-binding capacities were calculated through the analysis of breakthrough curves generated by monitoring the metal concentrations on a flow injection-flame atomic absorption system. Capacities for individual metals were comparable and in the order of Cu{sup 2+} >> Pb{sup 2+} > Ni{sup 2+} {approx} Cd{sup 2+} > Co{sup 2+} > Mn{sup 2+} >> Na{sup +}. Elemental combustion analysis yielded polymer coverage on the CPG of approximately 4 x 10{sup 12} to 5 x 10{sup 12} chains/cm{sup 2}, when average chain lengths were used in the calculations. Formation constants and site capacities of both polymers for Cd{sup 2+} were determined through equilibrium and breakthrough studies. The maximum log K values for the strong sites were determined to be {approx}13 for both PLAsp and for PLGlu. Additionally, the metal selectivity of PLAsp and PLGlu was evaluated when breakthrough curves were run with several metals present in solution at one time. Both polymers showed selectivities in the order of their single metal-binding capacities, i.e., Cu{sup 2+} > Pb{sup 2+} > Ni{sup 2+} {approx} Cd{sup 2+}. Both polymers exhibited similar binding trends and binding strengths for all of the metals studied. This likely reflects the absence of a predetermined tertiary structure of the polymers on the surface and the relatively high residue-per-metal ratio ({approx}20:1), which places less stringent requirements on the steric hindrance between the side chains and the resultant 'wrapping' of the peptide around the metal.

  18. Solvent-Free Polymerization of L-Aspartic Acid in the Presence of D-Sorbitol to Obtain Water Soluble or Network Copolymers

    Science.gov (United States)

    L-aspartic acid was thermally polymerized in the presence of D-sorbitol with the goal of synthesizing new, higher molecular weight water soluble and absorbent copolymers. No reaction occurred when aspartic acid alone was heated at 170 or 200 degrees C. In contrast, heating sorbitol and aspartic ac...

  19. Vibrational Spectroscopy and Phonon-Related Properties of the L-Aspartic Acid Anhydrous Monoclinic Crystal.

    Science.gov (United States)

    Silva, A M; Costa, S N; Sales, F A M; Freire, V N; Bezerra, E M; Santos, R P; Fulco, U L; Albuquerque, E L; Caetano, E W S

    2015-12-10

    The infrared absorption and Raman scattering spectra of the monoclinic P21 l-aspartic acid anhydrous crystal were recorded and interpreted with the help of density functional theory (DFT) calculations. The effect of dispersive forces was taken into account, and the optimized unit cells allowed us to obtain the vibrational normal modes. The computed data exhibits good agreement with the measurements for low wavenumbers, allowing for a very good assignment of the infrared and Raman spectral features. The vibrational spectra of the two lowest energy conformers of the l-aspartic molecule were also evaluated using the hybrid B3LYP functional for the sake of comparison, showing that the molecular calculations give a limited description of the measured IR and Raman spectra of the l-aspartic acid crystal for wavenumbers below 1000 cm(-1). The results obtained reinforce the need to use solid-state calculations to describe the vibrational properties of molecular crystals instead of calculations for a single isolated molecule picture even for wavenumbers beyond the range usually associated with lattice modes (200 cm(-1) < ω < 1000 cm(-1)).

  20. N-Methyl-D-aspartic Acid (NMDA in the nervous system of the amphioxus Branchiostoma lanceolatum

    Directory of Open Access Journals (Sweden)

    Garcia-Fernàndez Jordi

    2007-12-01

    Full Text Available Abstract Background NMDA (N-methyl-D-aspartic acid is a widely known agonist for a class of glutamate receptors, the NMDA type. Synthetic NMDA elicits very strong activity for the induction of hypothalamic factors and hypophyseal hormones in mammals. Moreover, endogenous NMDA has been found in rat, where it has a role in the induction of GnRH (Gonadotropin Releasing Hormone in the hypothalamus, and of LH (Luteinizing Hormone and PRL (Prolactin in the pituitary gland. Results In this study we show evidence for the occurrence of endogenous NMDA in the amphioxus Branchiostoma lanceolatum. A relatively high concentration of NMDA occurs in the nervous system of this species (3.08 ± 0.37 nmol/g tissue in the nerve cord and 10.52 ± 1.41 nmol/g tissue in the cephalic vesicle. As in rat, in amphioxus NMDA is also biosynthesized from D-aspartic acid (D-Asp by a NMDA synthase (also called D-aspartate methyl transferase. Conclusion Given the simplicity of the amphioxus nervous and endocrine systems compared to mammalian, the discovery of NMDA in this protochordate is important to gain insights into the role of endogenous NMDA in the nervous and endocrine systems of metazoans and particularly in the chordate lineage.

  1. Identification of Aspartic Acid Enantiomers Based on Molecularly Imprinted Polyaniline%Identification of Aspartic Acid Enantiomers Based on Molecularly Imprinted Polyaniline

    Institute of Scientific and Technical Information of China (English)

    孔泳; 姚超; 倪珺华; 周永生; 陈智栋

    2011-01-01

    Affinity sites for L-aspartic acid (L-Asp) in polyaniline (PAn) were created by two successive processes: first, L-Asp was simply added as template molecules during the polymerization of aniline; second, L-Asp incorporated in PAn backbone was extracted by solvent. PAn with cavities complementary to L-Asp template molecules has been utilized for enantioselective recognition of L- and D-Asp. Enantioselectivity of the imprinted PAn could be attributed to the cavities in the imprinted PAn which was complementary to L-Asp templates both in shape and in positioning of groups. Also in this paper, the structural changes before and after extraction of L-Asp templates were revealed by Fourier-transform infrared (FTIR) spectrum.

  2. A Concise Synthesis of Glycolipids Based on Aspartic Acid Building Blocks

    Directory of Open Access Journals (Sweden)

    Lorna Abbey

    2012-09-01

    Full Text Available L-Aspartic acid building blocks bearing galactosyl moieties were used to synthesise glycolipid mimetics of variable hydrocarbon chain length. The glycolipids were readily prepared through amide bond formation using the TBTU/HOBt coupling methodology. It was observed that, under these conditions, activation of the α-carboxylic acid of the intermediates led to near complete racemisation of the chiral centre if the reaction was carried out in the presence of a base such as triethylamine. The enantiomerically pure glycolipids were obtained after careful consideration of the synthetic sequence and by performing the coupling reactions in the absence of base.

  3. Inclusion Behavior of Dimer b-Cyclodextrin Bridged with Aspartic Acid Derivative

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The b-cyclodextrin (CD) dimer bridged with aspartic acid (ASP) derivative, FITC-ASP(NH-b-CD)2 (Host, FITC=fluorescein-4-isothiocyanate), was synthesized. Fluorescence polarization study showed that the novel host formed an inclusion compound, [FITC-ASP(NH-b-CD)2]ATA, for which Kd was determined to be 5.0×10-6 mol/L by Beacon 2000 Analyzer, when ATA (Guest) = Adm-Trp-Arg-Arg-NH2 (Adm = 1-adamantanecarboxylic acid, Trp = tryptophan, Arg = arginine), where Kd is the dissociation constant in aqueous solution at 298 K.

  4. Catalysis of the Oligomerization of O-Phospho-Serine, Aspartic Acid, or Glutamic Acid by Cationic Micelles

    Science.gov (United States)

    Boehler, Christof; Hill, Aubrey R., Jr.; Orgel, Leslie E.

    1996-01-01

    Treatment of relatively concentrated aqueous solutions of O-phospho-serine (50 mM), aspartic acid (100 mM) or glutamic acid (100 mM) with carbonyldiimidazole leads to the formation of an activated intermediate that oligomerizes efficiently. When the concentration of amino acid is reduced tenfold, few long oligomers can be detected. Positively-charged cetyltrimethyl ammonium bromide micelles concentrate the negatively-charged activated intermediates of the amino acids at their surfaces and catalyze efficient oligomerization even from dilute solutions.

  5. Aspartic acid-promoted highly selective and sensitive colorimetric sensing of cysteine in rat brain.

    Science.gov (United States)

    Qian, Qin; Deng, Jingjing; Wang, Dalei; Yang, Lifen; Yu, Ping; Mao, Lanqun

    2012-11-06

    Direct selective determination of cysteine in the cerebral system is of great importance because of the crucial roles of cysteine in physiological and pathological processes. In this study, we report a sensitive and selective colorimetric assay for cysteine in the rat brain with gold nanoparticles (Au-NPs) as the signal readout. Initially, Au-NPs synthesized with citrate as the stabilizer are red in color and exhibit absorption at 520 nm. The addition of an aqueous solution (20 μL) of cysteine or aspartic acid alone to a 200 μL Au-NP dispersion causes no aggregation, while the addition of an aqueous solution of cysteine into a Au-NP dispersion containing aspartic acid (1.8 mM) causes the aggregation of Au-NPs and thus results in the color change of the colloid from wine red to blue. These changes are ascribed to the ion pair interaction between aspartic acid and cysteine on the interface between Au-NPs and solution. The concentration of cysteine can be visualized with the naked eye and determined by UV-vis spectroscopy. The signal output shows a linear relationship for cysteine within the concentration range from 0.166 to 1.67 μM with a detection limit of 100 nM. The assay demonstrated here is highly selective and is free from the interference of other natural amino acids and other thiol-containing species as well as the species commonly existing in the brain such as lactate, ascorbic acid, and glucose. The basal dialysate level of cysteine in the microdialysate from the striatum of adult male Sprague-Dawley rats is determined to be around 9.6 ± 2.1 μM. The method demonstrated here is facile but reliable and durable and is envisaged to be applicable to understanding the chemical essence involved in physiological and pathological events associated with cysteine.

  6. Independent highly sensitive characterization of asparagine deamidation and aspartic acid isomerization by sheathless CZE-ESI-MS/MS.

    Science.gov (United States)

    Gahoual, Rabah; Beck, Alain; François, Yannis-Nicolas; Leize-Wagner, Emmanuelle

    2016-02-01

    Amino acids residues are commonly submitted to various physicochemical modifications occurring at physiological pH and temperature. Post-translational modifications (PTMs) require comprehensive characterization because of their major influence on protein structure and involvement in numerous in vivo process or signaling. Mass spectrometry (MS) has gradually become an analytical tool of choice to characterize PTMs; however, some modifications are still challenging because of sample faint modification levels or difficulty to separate an intact peptide from modified counterparts before their transfer to the ionization source. Here, we report the implementation of capillary zone electrophoresis coupled to electrospray ionization tandem mass spectrometry (CZE-ESI-MS/MS) by the intermediate of a sheathless interfacing for independent and highly sensitive characterization of asparagine deamidation (deaN) and aspartic acid isomerization (isoD). CZE selectivity regarding deaN and isoD was studied extensively using different sets of synthetic peptides based on actual tryptic peptides. Results demonstrated CZE ability to separate the unmodified peptide from modified homologous exhibiting deaN, isoD or both independently with a resolution systematically superior to 1.29. Developed CZE-ESI-MS/MS method was applied for the characterization of monoclonal antibodies and complex protein mixture. Conserved CZE selectivity could be demonstrated even for complex samples, and foremost results obtained showed that CZE selectivity is similar regardless of the composition of the peptide. Separation of modified peptides prior to the MS analysis allowed to characterize and estimate modification levels of the sample independently for deaN and isoD even for peptides affected by both modifications and, as a consequence, enables to distinguish the formation of l-aspartic acid or d-aspartic acid generated from deaN. Separation based on peptide modification allowed, as supported by the ESI

  7. Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS(3) experiments.

    Science.gov (United States)

    Boukerche, Toufik Taalibi; Alves, Sandra; Le Faouder, Pauline; Warnet, Anna; Bertrand-Michel, Justine; Bouchekara, Mohamed; Belbachir, Mohammed; Tabet, Jean-Claude

    2016-12-01

    Lipidomics calls for information on detected lipids and conjugates whose structural elucidation by mass spectrometry requires to rationalization of their gas phase dissociations toward collision-induced dissociation (CID) processes. This study focused on activated dissociations of two lipoamino acid (LAA) systems composed of N-palmitoyl acyl coupled with aspartic and glutamic acid mono ethyl esters (as LAA(*D) and LAA(*E)). Although in MS/MS, their CID spectra show similar trends, e.g., release of water and ethanol, the [(LAA(*D/*E)+H)-C2H5OH](+) product ions dissociate via distinct pathways in sequential MS(3) experiments. The formation of all the product ions is rationalized by charge-promoted cleavages often involving stepwise processes with ion isomerization into ion-dipole prior to dissociation. The latter explains the maleic anhydride or ketene neutral losses from N-palmitoyl acyl aspartate and glutamate anhydride fragment ions, respectively. Consequently, protonated palmitoyl acid amide is generated from LAA(*D), whereas LAA(*E) leads to the [*E+H-H2O](+) anhydride. The former releases ammonia to provide acylium, which gives the C n H(2n-1) and C n H(2n-3) carbenium series. This should offer structural information, e.g., to locate either unsaturation(s) or alkyl group branching present on the various fatty acyl moieties of lipo-aspartic acid in further studies based on MS (n) experiments.

  8. [Aspartic Acid Generated in the Process of Chlorination Disinfection By-product Dichloroacetonitrile].

    Science.gov (United States)

    Ding, Chun-sheng; Li, Nai-jun; Zhang, Tao; Zhang, Meng-qing

    2016-05-15

    In this study, a method was developed for the determination of dichloroacetonitrile (DCAN) in drinking water by liquid- liquid micro-extraction and gas chromatography/mass spectrometry ( LLE-GC/MS), which used 1,2-dibromopropane as the internal standard and methyl tertiary butyl ether (MTBE) as the extractant for high accuracy. The aspartic acid was used as the precursor of the DCAN formation during chlorination and the influencing factors were evaluated. The formation mechanism of DCAN was also discussed. The results showed that the DCAN amount increased with the increase of pH value under the neutral and acidic conditions, however, the amount of DCAN decreased with the increase of pH value under the alkali condition. And the final amount of DCAN under the alkali condition was much less than that under the neutral and acidic conditions. It was also found that the DCAN amount increased with the increase of chlorine addition, while the temperature in the range of 10-30°C had little influence on the DCAN formation. The formation process of the DCAN from aspartic acid by chlorination included seven steps, such as substitution, decarboxylation, oxidation, etc and ultimately formed DCAN.

  9. Hydroxylation of aspartic acid in domains homologous to the epidermal growth factor precursor is catalyzed by a 2-oxoglutarate-dependent dioxygenase.

    Science.gov (United States)

    Stenflo, J; Holme, E; Lindstedt, S; Chandramouli, N; Huang, L H; Tam, J P; Merrifield, R B

    1989-01-01

    3-Hydroxyaspartic acid and 3-hydroxyasparagine are two rare amino acids that are present in domains homologous to the epidermal growth factor precursor in vitamin K-dependent plasma proteins as well as in proteins that do not require vitamin K for normal biosynthesis. They are formed by posttranslational hydroxylation of aspartic acid and asparagine, respectively. The first epidermal growth factor-like domain in factor IX (residues 45-87) was synthesized with aspartic acid in position 64, replacing 3-hydroxyaspartic acid. It was used as substrate in a hydroxylase assay with rat liver microsomes as the source of enzyme and reaction conditions that satisfy the requirements of 2-oxoglutarate-dependent dioxygenases. The synthetic peptide stimulated the 2-oxoglutarate decarboxylation in contrast to synthetic, modified epidermal growth factor (Met-21 and His-22 deleted and Glu-24 replaced by Asp) and synthetic peptides corresponding to residues 60-71 in human factor IX. This indicates that the hydroxylase is a 2-oxoglutarate-dependent dioxygenase with a selective substrate requirement. Images PMID:2492106

  10. Question of the possible asymmetric polymerization of aspartic acid on kaolinite

    Energy Technology Data Exchange (ETDEWEB)

    McCullough, J.J.; Lemmon, R.M.

    1974-01-01

    McCullough and Lemmon have been unable to confirm the recent report that kaolinite catalyzes the polymerization of aqueous D- and L-aspartic acid at different rates. In experiments where DL-Asp was used, no induced optical rotation was found in the reaction solution. No evidence for polymer (or other product) formation was found when L-Asp-2-/sup 14/C was used, and products were searched by paper chromatography and x-ray film autoradiography. Asp is adsorbed by kaolinite, but no selectivity for one or the other enantiomer was observed.

  11. Aspartic acid racemization in dentin of the third molar for age estimation of the Chaoshan population in South China.

    Science.gov (United States)

    Chen, Shisheng; Lv, Yanyi; Wang, Dian; Yu, Xiaojun

    2016-09-01

    Aspartic acid racemization in teeth has been increasingly used to estimate chronological age with a considerably high accuracy in forensic practice. The Chaoshan population in South China is relatively isolated in geography, and has specific lifestyle and dietary inhibits. It is still unknown whether this method is suitable for this population. The aim of this study was to analyze the relationship between chronological age and the d/l aspartic acid ratio in dentin in the third molar tooth of the Chaoshan population. Fifty-eight non-carious third molar teeth (31 mandibles and 27 maxillae), from 58 living individuals of known age (24 males and 34 females), were retrieved. Dentin was extracted from these teeth. The d- and l-aspartic acids in dentins were separated and detected by high performance liquid chromatography (HPLC). Linear regression was performed between the d/l aspartic acid ratio of dentins and chronological age. Results showed that the correlation coefficient (r) was 0.969, and the mean absolute error (MAE) was 2.19 years, its standard deviation (SD) was ±1.53 years, indicating excellent correlation. There was no significant difference in racemization rates of dentin between sexes (P=0.113, F=2.6), or between mandibles and maxillae (P=0.964, F=0.000). Results indicate that the ratio of the d and l forms of aspartic acid of dentins, in the third molar, is closely correlated with chronological age, special lifestyle do no obviously affect the accuracy of the age estimations by aspartic acid racemization of the dentin in the third molar and that aspartic acid racemization in the third molar dentin can be used as an accurate method to estimate chronological age in the Chaoshan population in South China.

  12. Investigation of the conformation of aspartic acid by the NMR method

    Energy Technology Data Exchange (ETDEWEB)

    Tananaeva, N.N.; Gorokhovatskaya, M.Ya.; Tikhonova, R.V.; Kostromina, N.A.

    1986-01-01

    The conformations of aspartic acid were investigated in relation to the pH value by /sup 1/H and /sup 13/C NMR methods. It was shown that the form of the spectra becomes simpler in the transition from the alkaline to the acidic region and changes from an ABX to an A/sub 2/X system. The order of protonation of the donating groups was established. The spin-spin coupling constants at various pH values were calculated, and the conformational transitions were examined on the basis of their variation. The possibility of the closure of a six-membered ring in the molecule in the alkaline region and the opening of this ring in the acidic region was demonstrated.

  13. Protonation Equilibria of L-Aspartic, Citric and Succinic Acids in Anionic Micellar Media

    Directory of Open Access Journals (Sweden)

    P. Srinivasa Rao

    2009-01-01

    Full Text Available The impact of sodium lauryl sulphate (SLS on the protonation equilibria of L-aspartic acid, citric acid and succinic acid has been studied in various concentrations (0.5-2.5% w/v of SLS solution maintaining an ionic strength of 0.16 mol dm-3 at 303 K. The protonation constants have been calculated with the computer program MINIQUAD75 and the best fit models have been calculated based on statistical parameters. The trend of log values of step-wise protonation constants with mole fraction of the medium has been explained based on electrostatic and non-electrostatic forces operating on the protonation equilibria. The effects of errors on the protonation constants have also been presented.

  14. Proteaselike sequence in hepatitis B virus core antigen is not required for e antigen generation and may not be part of an aspartic acid-type protease.

    Science.gov (United States)

    Nassal, M; Galle, P R; Schaller, H

    1989-01-01

    The hepatitis B virus (HBV) C gene directs the synthesis of two major gene products: HBV core antigen (HBcAg[p21c]), which forms the nucleocapsid, and HBV e antigen (HBeAg [p17e]), a secreted antigen that is produced by several processing events during its maturation. These proteins contain an amino acid sequence similar to the active-site residues of aspartic acid and retroviral proteases. On the basis of this sequence similarity, which is highly conserved among mammalian hepadnaviruses, a model has been put forward according to which processing to HBeAg is due to self-cleavage of p21c involving the proteaselike sequence. Using site-directed mutagenesis in conjunction with transient expression of HBV proteins in the human hepatoma cell line HepG2, we tested this hypothesis. Our results with HBV mutants in which one or two of the conserved amino acids have been replaced by others suggest strongly that processing to HBeAg does not depend on the presence of an intact proteaselike sequence in the core protein. Attempts to detect an influence of this sequence on the processing of HBV P gene products into enzymatically active viral polymerase also gave no conclusive evidence for the existence of an HBV protease. Mutations replacing the putatively essential aspartic acid showed little effect on polymerase activity. Additional substitution of the likewise conserved threonine residue by alanine, in contrast, almost abolished the activity of the polymerase. We conclude that an HBV protease, if it exists, is functionally different from aspartic acid and retroviral proteases. Images PMID:2657101

  15. Intein-Promoted Cyclization of Aspartic Acid Flanking the Intein Leads to Atypical N-Terminal Cleavage.

    Science.gov (United States)

    Minteer, Christopher J; Siegart, Nicolle M; Colelli, Kathryn M; Liu, Xinyue; Linhardt, Robert J; Wang, Chunyu; Gomez, Alvin V; Reitter, Julie N; Mills, Kenneth V

    2017-02-28

    Protein splicing is a post-translational reaction facilitated by an intein, or intervening protein, which involves the removal of the intein and the ligation of the flanking polypeptides, or exteins. A DNA polymerase II intein from Pyrococcus abyssi (Pab PolII intein) can promote protein splicing in vitro on incubation at high temperature. Mutation of active site residues Cys1, Gln185, and Cys+1 to Ala results in an inactive intein precursor, which cannot promote the steps of splicing, including cleavage of the peptide bond linking the N-extein and intein (N-terminal cleavage). Surprisingly, coupling the inactivating mutations to a change of the residue at the C-terminus of the N-extein (N-1 residue) from the native Asn to Asp reactivates N-terminal cleavage at pH 5. Similar "aspartic acid effects" have been observed in other proteins and peptides but usually only occur at lower pH values. In this case, however, the unusual N-terminal cleavage is abolished by mutations to catalytic active site residues and unfolding of the intein, indicating that this cleavage effect is mediated by the intein active site and the intein fold. We show via mass spectrometry that the reaction proceeds through cyclization of Asp resulting in anhydride formation coupled to peptide bond cleavage. Our results add to the richness of the understanding of the mechanism of protein splicing and provide insight into the stability of proteins at moderately low pH. The results also explain, and may help practitioners avoid, a side reaction that may complicate intein applications in biotechnology.

  16. Negative ion photoelectron spectroscopy of the copper-aspartic acid anion and its hydrated complexes

    Science.gov (United States)

    Li, Xiang; Wang, Haopeng; Bowen, Kit H.; Martínez, Ana; Salpin, Jean-Yves; Schermann, Jean-Pierre

    2010-08-01

    Negative ions of copper-aspartic acid Cu(Asp)- and its hydrated complexes have been produced in the gas phase and studied by anion photoelectron spectroscopy. The vertical detachment energies (VDE) of Cu(Asp)- and Cu(Asp)-(H2O)1,2 were determined to be 1.6, 1.95, and 2.20 eV, respectively. The spectral profiles of Cu(Asp)-(H2O)1 and Cu(Asp)-(H2O)2 closely resembled that of Cu(Asp)-, indicating that hydration had not changed the structure of Cu(Asp)- significantly. The successive shifts to higher electron binding energies by the spectra of the hydrated species provided measures of their stepwise solvation energies. Density functional calculations were performed on anionic Cu(Asp)- and on its corresponding neutral. The agreement between the calculated and measured VDE values implied that the structure of the Cu(Asp)- complex originated with a zwitterionic form of aspartic acid in which a copper atom had inserted into the N-H bond.

  17. Multifunctional Environmental Smart Fertilizer Based on l-Aspartic Acid for Sustained Nutrient Release.

    Science.gov (United States)

    Lü, Shaoyu; Feng, Chen; Gao, Chunmei; Wang, Xinggang; Xu, Xiubin; Bai, Xiao; Gao, Nannan; Liu, Mingzhu

    2016-06-22

    Fertilizer is one of the most important elements of modern agriculture. However, conventional fertilizer, when applied to crops, is vulnerable to losses through volatilization, leaching, nitrification, or other means. Such a loss limits crop yields and pollutes the environment. In an effort to enhance nutrient use efficiency and reduce environmental pollution, an environmental smart fertilizer was reported in the current study. Poly(aspartic acid) and a degradable macro-cross-linker based on l-aspartic acid were synthesized and introduced into the fertilizer as a superabsorbent to improve the fertilizer degradability and soil moisture-retention capacity. Sustained release behavior of the fertilizer was achieved in soil. Cumulative release of nitrogen and phosphorus was 79.8% and 64.4% after 30 days, respectively. The water-holding and water-retention capacities of soil with the superabsorbent are obviously higher than those of the control soil without superabsorbent. For the sample of 200 g of soil with 1.5 g of superabsorbent, the water-holding capacity is 81.8%, and the water-retention capacity remains 22.6% after 23 days. All of the current results in this study indicated that the as-prepared fertilizer has a promising application in sustainable modern agriculture.

  18. Syntheses, Characterization, Resolution, and Biological Studies of Coordination Compounds of Aspartic Acid and Glycine.

    Science.gov (United States)

    Aiyelabola, Temitayo; Akinkunmi, Ezekiel; Ojo, Isaac; Obuotor, Efere; Adebajo, Clement; Isabirye, David

    2017-01-01

    Enantiomerically enriched coordination compounds of aspartic acid and racemic mixtures of coordination compounds of glycine metal-ligand ratio 1 : 3 were synthesized and characterized using infrared and UV-Vis spectrophotometric techniques and magnetic susceptibility measurements. Five of the complexes were resolved using (+)-cis-dichlorobis(ethylenediamine)cobalt(III) chloride, (+)-bis(glycinato)(1,10-phenanthroline)cobalt(III) chloride, and (+)-tris(1,10-phenanthroline)nickel(II) chloride as resolving agents. The antimicrobial and cytotoxic activities of these complexes were then determined. The results obtained indicated that aspartic acid and glycine coordinated in a bidentate fashion. The enantiomeric purity of the compounds was in the range of 22.10-32.10%, with (+)-cis-dichlorobis(ethylenediamine)cobalt(III) complex as the more efficient resolving agent. The resolved complexes exhibited better activity in some cases compared to the parent complexes for both biological activities. It was therefore inferred that although the increase in the lipophilicity of the complexes may assist in the permeability of the complexes through the cell membrane of the pathogens, the enantiomeric purity of the complexes is also of importance in their activity as antimicrobial and cytotoxic agents.

  19. Poly(aspartic acid) (PAA) hydrolases and PAA biodegradation: current knowledge and impact on applications.

    Science.gov (United States)

    Hiraishi, Tomohiro

    2016-02-01

    Thermally synthesized poly(aspartic acid) (tPAA) is a bio-based, biocompatible, biodegradable, and water-soluble polymer that has a high proportion of β-Asp units and equivalent moles of D- and L-Asp units. Poly(aspartic acid) (PAA) hydrolase-1 and hydrolase-2 are tPAA biodegradation enzymes purified from Gram-negative bacteria. PAA hydrolase-1 selectively cleaves amide bonds between β-Asp units via an endo-type process, whereas PAA hydrolase-2 catalyzes the exo-type hydrolysis of the products of tPAA hydrolysis by PAA hydrolase-1. The novel reactivity of PAA hydrolase-1 makes it a good candidate for a biocatalyst in β-peptide synthesis. This mini-review gives an overview of PAA hydrolases with emphasis on their biochemical and functional properties, in particular, PAA hydrolase-1. Functionally related enzymes, such as poly(R-3-hydroxybutyrate) depolymerases and β-aminopeptidases, are compared to PAA hydrolases. This mini-review also provides findings that offer an insight into the catalytic mechanisms of PAA hydrolase-1 from Pedobacter sp. KP-2.

  20. The induction of D-aspartic acid in mouse lens protein by continuous gamma-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tamanoi, Itsuro (Chiba Univ. (Japan)); Fujii, Noriko; Muraoka, Shiro; Harada, Kaoru; Joshima, Hisamasa; Ishihara, Takaaki

    1990-08-01

    The irradiation condition to induce the increase of D-aspartic acid (D-Asp), which is detected in aged human and animals, in a short term was studied by continuous low dose irradiation. The results were compared with the effect by a single X-ray irradiation. The continuous gamma-irradiation for 12 months with 83 mGy/day or 29 mGy/day from {sup 137}Cs could induce higher D/L ratio of aspartic acid (Asp) in the lens protein of RFM/MsNrs strain of mice. But the irradiation with 10 mGy/day for 14 months did not show the much increase of D-Asp in the lens protein of mice. In 14.5 months of post-X-irradiation to whole body with 5 Gy, a little higher ratio of D/L Asp was observed in the lens protein of BALB/cA strain of mice. These results indicate that it is possible to obtain the protein containing D-Asp by continuous low dose irradiation in a relatively short period. (author).

  1. Nanostructured aluminium oxide powders obtained by aspartic acid-nitrate gel-combustion routes

    Energy Technology Data Exchange (ETDEWEB)

    Gardey Merino, Maria Celeste, E-mail: mcgardey@frm.utn.edu.a [Laboratorio de Investigaciones y Servicios Ambientales Mendoza (LISAMEN) - CCT - CONICET, Avda. Ruiz Leal s/n, Parque Gral. San Martin, (M5502IRA) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Grupo CLIOPE, Universidad Tecnologica Nacional - Facultad Regional Mendoza, Rodriguez 273, (M5502AJE) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Lascalea, Gustavo E. [Laboratorio de Investigaciones y Servicios Ambientales Mendoza (LISAMEN) - CCT - CONICET, Avda. Ruiz Leal s/n, Parque Gral. San Martin, (M5502IRA) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Sanchez, Laura M. [CINSO (Centro de Investigaciones en Solidos), CITEFA - CONICET, J.B. de La Salle 4397, (B1603ALO) Villa Martelli, Prov. de Buenos Aires (Argentina); Vazquez, Patricia G. [Centro de Investigacion y Desarrollo en Ciencias Aplicadas ' Dr. Jorge J. Ronco' (CINDECA), CONICET, Universidad Nacional de La Plata, Calle 47 nro. 257, (B1900AJK) La Plata, Prov. de Buenos Aires (Argentina); Cabanillas, Edgardo D. [CONICET and Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); Lamas, Diego G. [CINSO (Centro de Investigaciones en Solidos), CITEFA - CONICET, J.B. de La Salle 4397, (B1603ALO) Villa Martelli, Prov. de Buenos Aires (Argentina)

    2010-04-16

    In this work, two new gel-combustion routes for the synthesis of Al{sub 2}O{sub 3} nanopowders with aspartic acid as fuel are presented. The first route is a conventional stoichiometric process, while the second one is a non-stoichiometric, pH-controlled process. These routes were compared with similar synthesis procedures using glycine as fuel, which are well-known in the literature. The samples were calcined in air at different temperatures, in a range of 600-1200 {sup o}C. They were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and BET specific surface area. Different phases were obtained depending on the calcination temperature: amorphous, {gamma} (metastable) or {alpha} (stable). The amorphous-to-{gamma} transition was found for calcination temperatures in the range of 700-900 {sup o}C, while the {gamma}-to-{alpha} one was observed for calcination temperatures of 1100-1200 {sup o}C. The retention of the metastable {gamma} phase is probably due to a crystallite size effect. It transforms to the {alpha} phase after the crystallite size increases over a critical size during the calcination process at 1200 {sup o}C. The highest BET specific surface areas were obtained for both nitrate-aspartic acid routes proposed in this work, reaching values of about 50 m{sup 2}/g.

  2. Syntheses, Characterization, Resolution, and Biological Studies of Coordination Compounds of Aspartic Acid and Glycine

    Science.gov (United States)

    Akinkunmi, Ezekiel; Ojo, Isaac; Adebajo, Clement; Isabirye, David

    2017-01-01

    Enantiomerically enriched coordination compounds of aspartic acid and racemic mixtures of coordination compounds of glycine metal-ligand ratio 1 : 3 were synthesized and characterized using infrared and UV-Vis spectrophotometric techniques and magnetic susceptibility measurements. Five of the complexes were resolved using (+)-cis-dichlorobis(ethylenediamine)cobalt(III) chloride, (+)-bis(glycinato)(1,10-phenanthroline)cobalt(III) chloride, and (+)-tris(1,10-phenanthroline)nickel(II) chloride as resolving agents. The antimicrobial and cytotoxic activities of these complexes were then determined. The results obtained indicated that aspartic acid and glycine coordinated in a bidentate fashion. The enantiomeric purity of the compounds was in the range of 22.10–32.10%, with (+)-cis-dichlorobis(ethylenediamine)cobalt(III) complex as the more efficient resolving agent. The resolved complexes exhibited better activity in some cases compared to the parent complexes for both biological activities. It was therefore inferred that although the increase in the lipophilicity of the complexes may assist in the permeability of the complexes through the cell membrane of the pathogens, the enantiomeric purity of the complexes is also of importance in their activity as antimicrobial and cytotoxic agents. PMID:28293149

  3. Molecularly imprinted polymer-matrix nanocomposite for enantioselective electrochemical sensing of D- and L-aspartic acid.

    Science.gov (United States)

    Prasad, Bhim Bali; Srivastava, Amrita; Tiwari, Mahavir Prasad

    2013-10-01

    A new molecularly imprinted polymer-matrix (titanium dioxide nanoparticle/multiwalled carbon nanotubes) nanocomposite was developed for the modification of pencil graphite electrode as an enantioselective sensing probe for aspartic acid isomers, prevalent at ultra trace level in aqueous and real samples. The nanocomposite having many shape complementary cavities was synthesized adopting surface initiated-activators regenerated by electron transfer for atom transfer radical polymerization. The proposed sensor has high stability, nanocomposite uniformity, good reproducibility, and enhanced electrocatalytic activity to respond oxidative peak current of L-aspartic acid quantitatively by differential pulse anodic stripping voltammetry, without any cross-reactivity in real samples. Under the optimized operating conditions, the L-aspartic acid imprinted modified electrode showed a wide linear response for L-aspartic acid within the concentration range 9.98-532.72 ng mL(-1), with the minimum detection limit of 1.73-1.79 ng mL(-1) (S/N=3) in aqueous and real samples. Almost similar stringent limit (1.79 ng mL(-1)) was obtained with cerebrospinal fluid which is typical for the primitive diagnosis of neurological disorders, caused by an acute depletion of L-aspartic acid biomarker, in clinical settings.

  4. Aspartic acid aminotransferase activity is increased in actively spiking compared with non-spiking human epileptic cortex.

    Science.gov (United States)

    Kish, S J; Dixon, L M; Sherwin, A L

    1988-01-01

    Increased concentration of the excitatory neurotransmitter aspartic acid in actively spiking human epileptic cerebral cortex was recently described. In order to further characterise changes in the aspartergic system in epileptic brain, the behaviour of aspartic acid aminotransferase (AAT), a key enzyme involved in aspartic acid metabolism has now been examined. Electrocorticography performed during surgery was employed to identify cortical epileptic spike foci in 16 patients undergoing temporal lobectomy for intractable seizures. Patients with spontaneously spiking lateral temporal cortex (n = 8) were compared with a non-spiking control group (n = 8) of patients in whom the epileptic lesions were confined to the hippocampus sparing the temporal convexity. Mean activity of AAT in spiking cortex was significantly elevated by 16-18%, with aspartic acid concentration increased by 28%. Possible explanations for the enhanced AAT activity include increased proliferation of cortical AAT-containing astrocytes at the spiking focus and/or a generalised increase in neuronal or extraneuronal metabolism consequent to the ongoing epileptic discharge. It is suggested that the data provide additional support for a disturbance of central excitatory aspartic acid mechanisms in human epileptic brain. PMID:2898010

  5. Development of poly(aspartic acid-co-malic acid) composites for calcium carbonate and sulphate scale inhibition.

    Science.gov (United States)

    Mithil Kumar, N; Gupta, Sanjay Kumar; Jagadeesh, Dani; Kanny, K; Bux, F

    2015-01-01

    Polyaspartic acid (PSI) is suitable for the inhibition of inorganic scale deposition. To enhance its scale inhibition efficiency, PSI was modified by reacting aspartic acid with malic acid (MA) using thermal polycondensation polymerization. This reaction resulted in poly(aspartic acid-co-malic acid) (PSI-co-MA) dual polymer. The structural, chemical and thermal properties of the dual polymers were analysed by using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and gel permeation chromatography. The effectiveness of six different molar ratios of PSI-co-MA dual polymer for calcium carbonate and calcium sulphate scale inhibition at laboratory scale batch experiments was evaluated with synthetic brine solution at selected doses of polymer at 65-70°C by the static scale test method. The performance of PSI-co-MA dual polymer for the inhibition of calcium carbonate and calcium sulphate precipitation was compared with that of a PSI single polymer. The PSI-co-MA exhibited excellent ability to control inorganic minerals, with approximately 85.36% calcium carbonate inhibition and 100% calcium sulphate inhibition at a level of 10 mg/L PSI-co-MA, respectively. Therefore, it may be reasonably concluded that PSI-co-MA is a highly effective scale inhibitor for cooling water treatment applications.

  6. Cholinesterase-like domains in enzymes and structural proteins: functional and evolutionary relationships and identification of a catalytically essential aspartic acid.

    Science.gov (United States)

    Krejci, E; Duval, N; Chatonnet, A; Vincens, P; Massoulié, J

    1991-01-01

    Primary sequences of cholinesterases and related proteins have been systematically compared. The cholinesterase-like domain of these proteins, about 500 amino acids, may fulfill a catalytic and a structural function. We identified an aspartic acid residue that is conserved among esterases and lipases (Asp-397 in Torpedo acetylcholinesterase) but that had not been considered to be involved in the catalytic mechanism. Site-directed mutagenesis demonstrated that this residue is necessary for activity. Analysis of evolutionary relationships shows that the noncatalytic members of the family do not constitute a separate subgroup, suggesting that loss of catalytic activity occurred independently on several occasions, probably from bifunctional molecules. Cholinesterases may thus be involved in cell-cell interactions in addition to the hydrolysis of acetylcholine. This would explain their specific expression in well-defined territories during embryogenesis before the formation of cholinergic synapses and their presence in noncholinergic tissues. Images PMID:1862088

  7. Effects of L-Aspartic acid on the step retreat kinetics of calcite

    Science.gov (United States)

    Yoshino, Toru; Kagi, Hiroyuki

    2012-01-01

    Effects of L-Aspartic acid (L-Asp) on step retreat kinetics in the dissolution of calcite were investigated. The step retreat velocities under surface-controlled kinetics were determined from in-situ atomic force microscopic observations using an improved flow-through system. Comparison of the present results with those obtained under a mixed kinetics condition revealed that the addition of L-Asp promotes the transport process in the calcite dissolution through acid-base and/or complex forming reactions in the diffusion boundary layer. Additionally, promotion of the acute and obtuse step retreats by the L-Asp additive was observed under surface-controlled kinetics. This report is the first to clarify that L-Asp promotes surface processes in the dissolution of calcite.

  8. In vitro testing of thiolated poly(aspartic acid) from ophthalmic formulation aspects.

    Science.gov (United States)

    Budai-Szű Cs, Mária; Horvát, Gabriella; Gyarmati, Benjámin; Szilágyi, Barnabás Áron; Szilágyi, András; Csihi, Tímea; Berkó, Szilvia; Szabó-Révész, Piroska; Mori, Michela; Sandri, Giuseppina; Bonferoni, Maria Cristina; Caramella, Carla; Csányi, Erzsébet

    2016-08-01

    Ocular drug delivery formulations must meet anatomical, biopharmaceutical, patient-driven and regulatory requirements. Mucoadhesive polymers can serve as a better alternative to currently available ophthalmic formulations by providing improved bioavailability. If all requirements are addressed, a polymeric formulation resembling the tear film of the eye might be the best solution. The optimum formulation must not have high osmotic activity, should provide appropriate surface tension, pH and refractive index, must be non-toxic and should be transparent and mucoadhesive. We would like to highlight the importance of in vitro polymer testing from a pharmaceutical aspect. We, therefore, carried out physical-chemical investigations to verify the suitability of certain systems for ophthalmic formulations. In this work, in situ gelling, mucoadhesive thiolated poly(aspartic acid)s were tested from ophthalmic formulation aspects. The results of preformulation measurements indicate that these polymers can be used as potential carriers in ophthalmic drug delivery.

  9. Endolithic aspartic acid as a proxy of fluctuations in coral growth

    Science.gov (United States)

    Gupta, Lallan P.; Suzuki, Atsushi; Kawahata, Hodaka

    2007-03-01

    Coral skeleton has been widely studied for monitoring past fluctuations in marine environment. Although stable carbon isotope (δ13C) data appear to reflect coral metabolism, their interpretations differ from place to place and are sometimes controversial, because they are also affected by carbon isotopic composition of dissolved inorganic carbon in seawater. Association of an organic matrix with biological carbonates has been reported in many previous studies. With the help of high-resolution microsampling of coral skeleton and advanced technique for amino acid (AA) quantification in low-volume sample, we show that aspartic acid (Asp) in coral skeleton varies with distinct seasonal pattern, and is useful in understanding why corals calcify faster in summer than in winter. Since Asp containing organic matrix in the skeleton is synthesized by the coral, changes in mole concentration of Asp relative to other AAs of the skeleton make it a potential indicator for monitoring fluctuations in coral physiology in the past.

  10. Synthesis, Characterization, and Antimicrobial Activities of Coordination Compounds of Aspartic Acid

    Directory of Open Access Journals (Sweden)

    T. O. Aiyelabola

    2016-01-01

    Full Text Available Coordination compounds of aspartic acid were synthesized in basic and acidic media, with metal ligand M : L stoichiometric ratio 1 : 2. The complexes were characterized using infrared, electronic and magnetic susceptibility measurements, and mass spectrometry. Antimicrobial activity of the compounds was determined against three Gram-positive and three Gram-negative bacteria and one fungus. The results obtained indicated that the availability of donor atoms used for coordination was a function of the pH of the solution in which the reaction was carried out. This resulted in varying geometrical structures for the complexes. The compounds exhibited a broad spectrum of activity and in some cases better activity than the standard.

  11. Solution structure of the squash aspartic acid proteinase inhibitor (SQAPI) and mutational analysis of pepsin inhibition.

    Science.gov (United States)

    Headey, Stephen J; Macaskill, Ursula K; Wright, Michele A; Claridge, Jolyon K; Edwards, Patrick J B; Farley, Peter C; Christeller, John T; Laing, William A; Pascal, Steven M

    2010-08-27

    The squash aspartic acid proteinase inhibitor (SQAPI), a proteinaceous proteinase inhibitor from squash, is an effective inhibitor of a range of aspartic proteinases. Proteinaceous aspartic proteinase inhibitors are rare in nature. The only other example in plants probably evolved from a precursor serine proteinase inhibitor. Earlier work based on sequence homology modeling suggested SQAPI evolved from an ancestral cystatin. In this work, we determined the solution structure of SQAPI using NMR and show that SQAPI shares the same fold as a plant cystatin. The structure is characterized by a four-strand anti-parallel beta-sheet gripping an alpha-helix in an analogous manner to fingers of a hand gripping a tennis racquet. Truncation and site-specific mutagenesis revealed that the unstructured N terminus and the loop connecting beta-strands 1 and 2 are important for pepsin inhibition, but the loop connecting strands 3 and 4 is not. Using ambiguous restraints based on the mutagenesis results, SQAPI was then docked computationally to pepsin. The resulting model places the N-terminal strand of SQAPI in the S' side of the substrate binding cleft, whereas the first SQAPI loop binds on the S side of the cleft. The backbone of SQAPI does not interact with the pepsin catalytic Asp(32)-Asp(215) diad, thus avoiding cleavage. The data show that SQAPI does share homologous structural elements with cystatin and appears to retain a similar protease inhibitory mechanism despite its different target. This strongly supports our hypothesis that SQAPI evolved from an ancestral cystatin.

  12. Solution Structure of the Squash Aspartic Acid Proteinase Inhibitor (SQAPI) and Mutational Analysis of Pepsin Inhibition

    Science.gov (United States)

    Headey, Stephen J.; MacAskill, Ursula K.; Wright, Michele A.; Claridge, Jolyon K.; Edwards, Patrick J. B.; Farley, Peter C.; Christeller, John T.; Laing, William A.; Pascal, Steven M.

    2010-01-01

    The squash aspartic acid proteinase inhibitor (SQAPI), a proteinaceous proteinase inhibitor from squash, is an effective inhibitor of a range of aspartic proteinases. Proteinaceous aspartic proteinase inhibitors are rare in nature. The only other example in plants probably evolved from a precursor serine proteinase inhibitor. Earlier work based on sequence homology modeling suggested SQAPI evolved from an ancestral cystatin. In this work, we determined the solution structure of SQAPI using NMR and show that SQAPI shares the same fold as a plant cystatin. The structure is characterized by a four-strand anti-parallel β-sheet gripping an α-helix in an analogous manner to fingers of a hand gripping a tennis racquet. Truncation and site-specific mutagenesis revealed that the unstructured N terminus and the loop connecting β-strands 1 and 2 are important for pepsin inhibition, but the loop connecting strands 3 and 4 is not. Using ambiguous restraints based on the mutagenesis results, SQAPI was then docked computationally to pepsin. The resulting model places the N-terminal strand of SQAPI in the S′ side of the substrate binding cleft, whereas the first SQAPI loop binds on the S side of the cleft. The backbone of SQAPI does not interact with the pepsin catalytic Asp32–Asp215 diad, thus avoiding cleavage. The data show that SQAPI does share homologous structural elements with cystatin and appears to retain a similar protease inhibitory mechanism despite its different target. This strongly supports our hypothesis that SQAPI evolved from an ancestral cystatin. PMID:20538608

  13. Chlorogenic acid increased 5-hydroxymethylfurfural formation when heating fructose alone or with aspartic acid at two pH levels.

    Science.gov (United States)

    Zhang, Zhenhua; Zou, Yueyu; Wu, Taigang; Huang, Caihuan; Pei, Kehan; Zhang, Guangwen; Lin, Xiaohua; Bai, Weibin; Ou, Shiyi

    2016-01-01

    Chlorogenic acid (CGA) is a phenolic acid that ubiquitously exists in fruits. This work aims to investigate whether and how CGA influences HMF formation during heating fructose alone, or with an amino acid. The results showed that that CGA increased 5-hydroxymethylfurfural (HMF) formation. At pH 5.5 and 7.0, the addition of 5.0 μmol/ml CGA increased HMF formation by 49.4% and 25.2%, respectively when heating fructose alone, and by 9.0% and 16.7%, respectively when heating fructose with aspartic acid. CGA significantly increased HMF formation by promoting 3-deoxosone formation, and its conversion to HMF by inhibiting HMF elimination, especially in the Maillard reaction system. A comparison of the catalytic capacity of CGA with its six analogous compounds showed that both its di-hydroxyphenyl and carboxyl groups function in increasing HMF formation.

  14. Aspartic acid complexation of Am(III) and U(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Saito, A.; Choppin, G.R.

    1984-01-01

    Stability constants of Am(III) and U(VI) with L-aspartic acid have been determined at pH 8.00 by means of the solvent extraction technique. It was found that Am(III) forms 1:1 and 1:2 complexes while U(VI) formed only the 1:1 complex under these conditions. The stability constants were: Am/sup +3/: I = 0.10 M; log ..beta../sub 1/ = 4.81 +- 0.03, log ..beta../sub 2/ = 6.75 +- 0.03 I = 0.70 M; log ..beta../sub 1/ = 4.53 +- 0.08 log ..beta../sub 2/ = 6.65 +- 0.06 UO/sup +2//sub 2/: I = 0.70 M; log ..beta../sub 1/ = 3.32 +- 0.04. Comparison of these stability constants with corresponding values of some dicarboxylate ligands suggests that at pH 8 the binding of Am/sup +3/ and UO/sup +2//sub 2/ involves both carboxylates. In the Am-aspartate complex, the data indicate the possibility of weak interaction between the Am/sup +3/ and the amino group.

  15. Molecularly imprinted polymer-matrix nanocomposite for enantioselective electrochemical sensing of D- and L-aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Bhim Bali, E-mail: prof.bbpd@yahoo.com; Srivastava, Amrita; Tiwari, Mahavir Prasad

    2013-10-15

    A new molecularly imprinted polymer-matrix (titanium dioxide nanoparticle/multiwalled carbon nanotubes) nanocomposite was developed for the modification of pencil graphite electrode as an enantioselective sensing probe for aspartic acid isomers, prevalent at ultra trace level in aqueous and real samples. The nanocomposite having many shape complementary cavities was synthesized adopting surface initiated-activators regenerated by electron transfer for atom transfer radical polymerization. The proposed sensor has high stability, nanocomposite uniformity, good reproducibility, and enhanced electrocatalytic activity to respond oxidative peak current of L-aspartic acid quantitatively by differential pulse anodic stripping voltammetry, without any cross-reactivity in real samples. Under the optimized operating conditions, the L-aspartic acid imprinted modified electrode showed a wide linear response for L-aspartic acid within the concentration range 9.98–532.72 ng mL{sup −1}, with the minimum detection limit of 1.73–1.79 ng mL{sup −1} (S/N = 3) in aqueous and real samples. Almost similar stringent limit (1.79 ng mL{sup −1}) was obtained with cerebrospinal fluid which is typical for the primitive diagnosis of neurological disorders, caused by an acute depletion of L-aspartic acid biomarker, in clinical settings. Highlights: • We have adopted surface initiated-activators regenerated by electron transfer for atom transfer radical polymerization. • This approach takes advantage of the nanostructured ultrathin imprinted film. • Successful enantioselective sensing and ultratrace analysis of D- and L-aspartic acid. • Stringent detection limit without any non-specific false-positive contribution.

  16. Energetics and Dynamics of the Fragmentation Reactions of Protonated Peptides Containing Methionine Sulfoxide or Aspartic Acid via Energy- and Time-Resolved Surface Induced Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Lioe, Hadi; Laskin, Julia; Reid, Gavin E.; O' Hair, Richard Aj

    2007-10-25

    The surface-induced dissociation (SID) of six model peptides containing either methionine sulfoxide or aspartic acid (GAILM(O)GAILR, GAILM(O)GAILK, GAILM(O)GAILA, GAILDGAILR, GAILDGAILK, and GAILDGAILA) have been studied using a specially configured Fourier transform ion-cyclotron resonance mass spectrometer (FT-ICR MS). In particular, we have investigated the energetics and dynamics associated with (i) preferential cleavage of the methionine sulfoxide side chain via the loss of CH3SOH (64Da), and (ii) preferential cleavage of the amide bond C-terminal to aspartic acid. The role of proton mobility on these selective bond cleavage reactions was examined by changing the C-terminal residue of the peptide from arginine (non-mobile proton conditions) to lysine (partially-mobile proton conditions) to alanine (mobile proton conditions). Time- and energy-resolved fragmentation efficiency curves (TFEC) reveals that selective cleavages due to the methionine sulfoxide and aspartic acid residues are characterized by slow fragmentation kinetics. RRKM modeling of the experimental data suggests that the slow kinetics is associated with large negative entropy effects and these may be due to the presence of rearrangements prior to fragmentation. It was found that the Arrhenius pre-exponential factor (A) for peptide fragmentations occurring via selective bond cleavages are 1–2 orders of magnitude lower than non-selective peptide fragmentation reactions, while the dissociation threshold (E0) is relatively invariant. This means that selective bond cleavage is kinetically disfavored compared to non-selective amide bond cleavage. It was also found that the energetics and dynamics for the preferential loss of CH3SOH from peptide ions containing methionine sulfoxide are very similar to selective C-terminal amide bond cleavage at the aspartic acid residue. These results suggest that while preferential cleavage can compete with amide bond cleavage energetically, dynamically, these

  17. An invariant aspartic acid in the DNA glycosylase domain of DEMETER is necessary for transcriptional activation of the imprinted MEDEA gene

    Science.gov (United States)

    Choi, Yeonhee; Harada, John J.; Goldberg, Robert B.; Fischer, Robert L.

    2004-01-01

    Helix-hairpin-helix DNA glycosylases are typically small proteins that initiate repair of DNA by excising damaged or mispaired bases. An invariant aspartic acid in the active site is involved in catalyzing the excision reaction. Replacement of this critical residue with an asparagine severely reduces catalytic activity but preserves enzyme stability and structure. The Arabidopsis DEMETER (DME) gene encodes a large 1,729-aa polypeptide with a 200-aa DNA glycosylase domain. DME is expressed primarily in the central cell of the female gametophyte. DME activates maternal allele expression of the imprinted MEDEA (MEA) gene in the central cell and is required for seed viability. We mutated the invariant aspartic acid at position 1304 in DME to asparagine (D1304N) to determine whether the catalytic activity of the DNA glycosylase domain is required for DME function in vivo. Transgenes expressing wild-type DME in the central cell rescue seed abortion caused by a mutation in the endogenous DME gene and activate maternal MEA:GFP transcription. However, transgenes expressing the D1304N mutant DME do not rescue seed abortion or activate maternal MEA:GFP transcription. Whereas ectopic expression of the wild-type DME polypeptide in pollen is sufficient to activate ectopic paternal MEA and MEA:GUS expression, equivalent expression of the D1304N mutant DME in pollen failed to do so. These results show that the conserved aspartic acid residue is necessary for DME to function in vivo and suggest that an active DNA glycosylase domain, normally associated with DNA repair, promotes gene transcription that is essential for gene imprinting. PMID:15128940

  18. Ab initio studies of aspartic acid conformers in gas phase and in solution

    Science.gov (United States)

    Chen, Mingliang; Lin, Zijing

    2007-10-01

    Systematic and extensive conformational searches of aspartic acid in gas phase and in solution have been performed. For the gaseous aspartic acid, a total of 1296 trial canonical structures and 216 trial zwitterionic structures were generated by allowing for all combinations of internal single-bond rotamers. All the trial structures were optimized at the B3LYP /6-311G* level and then subjected to further optimization at the B3LYP /6-311++G** level. A total of 139 canonical conformers were found, but no stable zwitterionic structure was found. The rotational constants, dipole moments, zero-point vibrational energies, harmonic frequencies, and vertical ionization energies of the canonical conformers were determined. Single-point energies were also calculated at the MP2/6-311++G** and CCSD /6-311++G** levels. The equilibrium distributions of the gaseous conformers at various temperatures were calculated. The proton affinity and gas phase basicity were calculated and the results are in excellent agreement with the experiments. The conformations in the solution were studied with different solvation models. The 216 trial zwitterionic structures were first optimized at the B3LYP /6-311G* level using the Onsager self-consistent reaction field model (SCRF) and then optimized at the B3LYP /6-311++G** level using the conductorlike polarized continuum model (CPCM) SCRF theory. A total of 22 zwitterions conformers were found. The gaseous canonical conformers were combined with the CPCM model and optimized at the B3LYP /6-311++G** level. The solvated zwitterionic and canonical structures were further examined by the discrete/SCRF model with one and two water molecules. The incremental solvation of the canonical and zwitterionic structures with up to six water molecules in gas phase was systematically examined. The studies show that combining aspartic acid with at least six water molecules in the gas phase or two water molecules and a SCRF solution model is required to provide

  19. Poly(ethylenimine)-grafted-poly[(aspartic acid)-co-lysine]:A Non-viral Polymer with Potential for DNA Delivery

    Institute of Scientific and Technical Information of China (English)

    Zhi YANG; Gu Ping TANG

    2004-01-01

    A biodegradable gene transfer vector, poly(ethylenimine)-grafted-poly[(aspartic acid)-co-lysine] has been developed by thermal polycondensation of aspartic acid and lysine, and branch poly(ethylenimine) (Mw less than 600) was grafted to the backbone. The polymer was characterized by 1H NMR. It appeared lower cytotoxity compared to poly(ethylenimine) (25KDa), which was quantified by MTT assay. Electrophoresis indicated that the polymer could retardate DNA at N/P ratio 1.2-1.8 (w/w). Transfection efficiency of the complexes was studied in NT2 cell lines. It was 1.5 fold higher than molecular weight PEI (Mw = 25KDa).

  20. Neuroprotective Effect of Tauroursodeoxycholic Acid on N-Methyl-D-Aspartate-Induced Retinal Ganglion Cell Degeneration.

    Directory of Open Access Journals (Sweden)

    Violeta Gómez-Vicente

    Full Text Available Retinal ganglion cell degeneration underlies the pathophysiology of diseases affecting the retina and optic nerve. Several studies have previously evidenced the anti-apoptotic properties of the bile constituent, tauroursodeoxycholic acid, in diverse models of photoreceptor degeneration. The aim of this study was to investigate the effects of systemic administration of tauroursodeoxycholic acid on N-methyl-D-aspartate (NMDA-induced damage in the rat retina using a functional and morphological approach. Tauroursodeoxycholic acid was administered intraperitoneally before and after intravitreal injection of NMDA. Three days after insult, full-field electroretinograms showed reductions in the amplitudes of the positive and negative-scotopic threshold responses, scotopic a- and b-waves and oscillatory potentials. Quantitative morphological evaluation of whole-mount retinas demonstrated a reduction in the density of retinal ganglion cells. Systemic administration of tauroursodeoxycholic acid attenuated the functional impairment induced by NMDA, which correlated with a higher retinal ganglion cell density. Our findings sustain the efficacy of tauroursodeoxycholic acid administration in vivo, suggesting it would be a good candidate for the pharmacological treatment of degenerative diseases coursing with retinal ganglion cell loss.

  1. IRBIT Interacts with the Catalytic Core of Phosphatidylinositol Phosphate Kinase Type Iα and IIα through Conserved Catalytic Aspartate Residues.

    Directory of Open Access Journals (Sweden)

    Hideaki Ando

    Full Text Available Phosphatidylinositol phosphate kinases (PIPKs are lipid kinases that generate phosphatidylinositol 4,5-bisphosphate (PI(4,5P2, a critical lipid signaling molecule that regulates diverse cellular functions, including the activities of membrane channels and transporters. IRBIT (IP3R-binding protein released with inositol 1,4,5-trisphosphate is a multifunctional protein that regulates diverse target proteins. Here, we report that IRBIT forms signaling complexes with members of the PIPK family. IRBIT bound to all PIPK isoforms in heterologous expression systems and specifically interacted with PIPK type Iα (PIPKIα and type IIα (PIPKIIα in mouse cerebellum. Site-directed mutagenesis revealed that two conserved catalytic aspartate residues of PIPKIα and PIPKIIα are involved in the interaction with IRBIT. Furthermore, phosphatidylinositol 4-phosphate, Mg2+, and/or ATP interfered with the interaction, suggesting that IRBIT interacts with catalytic cores of PIPKs. Mutations of phosphorylation sites in the serine-rich region of IRBIT affected the selectivity of its interaction with PIPKIα and PIPKIIα. The structural flexibility of the serine-rich region, located in the intrinsically disordered protein region, is assumed to underlie the mechanism of this interaction. Furthermore, in vitro binding experiments and immunocytochemistry suggest that IRBIT and PIPKIα interact with the Na+/HCO3- cotransporter NBCe1-B. These results suggest that IRBIT forms signaling complexes with PIPKIα and NBCe1-B, whose activity is regulated by PI(4,5P2.

  2. Posttranslational nitration of tyrosine residues modulates glutamate transmission and contributes to N-methyl-D-aspartate-mediated thermal hyperalgesia.

    Science.gov (United States)

    Muscoli, Carolina; Dagostino, Concetta; Ilari, Sara; Lauro, Filomena; Gliozzi, Micaela; Bardhi, Erlisa; Palma, Ernesto; Mollace, Vincenzo; Salvemini, Daniela

    2013-01-01

    Activation of the N-methyl-D-aspartate receptor (NMDAR) is fundamental in the development of hyperalgesia. Overactivation of this receptor releases superoxide and nitric oxide that, in turn, forms peroxynitrite (PN). All of these events have been linked to neurotoxicity. The receptors and enzymes involved in the handling of glutamate pathway--specifically NMDARs, glutamate transporter, and glutamine synthase (GS)--have key tyrosine residues which are targets of the nitration process causing subsequent function modification. Our results demonstrate that the thermal hyperalgesia induced by intrathecal administration of NMDA is associated with spinal nitration of GluN1 and GluN2B receptor subunits, GS, that normally convert glutamate into nontoxic glutamine, and glutamate transporter GLT1. Intrathecal injection of PN decomposition catalyst FeTM-4-PyP(5+) prevents nitration and overall inhibits NMDA-mediated thermal hyperalgesia. Our study supports the hypothesis that nitration of key proteins involved in the regulation of glutamate transmission is a crucial pathway used by PN to mediate the development and maintenance of NMDA-mediated thermal hyperalgesia. The broader implication of our findings reinforces the notion that free radicals may contribute to various forms of pain events and the importance of the development of new pharmacological tool that can modulate the glutamate transmission without blocking its actions directly.

  3. Quantum Computational Calculations of the Ionization Energies of Acidic and Basic Amino Acids: Aspartate, Glutamate, Arginine, Lysine, and Histidine

    Science.gov (United States)

    de Guzman, C. P.; Andrianarijaona, M.; Lee, Y. S.; Andrianarijaona, V.

    An extensive knowledge of the ionization energies of amino acids can provide vital information on protein sequencing, structure, and function. Acidic and basic amino acids are unique because they have three ionizable groups: the C-terminus, the N-terminus, and the side chain. The effects of multiple ionizable groups can be seen in how Aspartate's ionizable side chain heavily influences its preferred conformation (J Phys Chem A. 2011 April 7; 115(13): 2900-2912). Theoretical and experimental data on the ionization energies of many of these molecules is sparse. Considering each atom of the amino acid as a potential departing site for the electron gives insight on how the three ionizable groups affect the ionization process of the molecule and the dynamic coupling between the vibrational modes. In the following study, we optimized the structure of each acidic and basic amino acid then exported the three dimensional coordinates of the amino acids. We used ORCA to calculate single point energies for a region near the optimized coordinates and systematically went through the x, y, and z coordinates of each atom in the neutral and ionized forms of the amino acid. With the calculations, we were able to graph energy potential curves to better understand the quantum dynamic properties of the amino acids. The authors thank Pacific Union College Student Association for providing funds.

  4. Effect of abomasal infusion of aspartate on nitrogen balance and plasma amino acids in Holstein steers.

    Science.gov (United States)

    Wessels, R H; Titgemeyer, E C

    1998-01-01

    We investigated the effect of abomasally infused aspartate (Asp) on N balance and plasma amino acids in steers. Four ruminally cannulated Holstein steers (180 kg) housed in metabolism crates were used in an experiment designed as a 4 x 3 Youden square. Steers received continuous abomasal infusions of water or water containing 40 or 80 g Asp/d. Steers were fed twice daily a diet containing 473 g/kg corn, 463 g/kg alfalfa hay and 52 g/kg soybean meal at levels near ad libitum intake. Abomasally infused Asp had no effect on N balance. Infusion of 80 g Asp/d increased (P < 0.05) plasma concentrations of Asp, glutamate and alanine. Metabolism of Asp by gut tissues probably prevented the large change in plasma concentration of Asp that seems necessary to trigger hormonal responses. We conclude that abomasal supplementation of steers with up to 80 g/d of Asp does not enhance performance.

  5. Self-assembling of poly(aspartic acid) with bovine serum albumin in aqueous solutions.

    Science.gov (United States)

    Nita, L E; Chiriac, A P; Bercea, M; Asandulesa, M; Wolf, Bernhard A

    2017-02-01

    Macromolecular co-assemblies built up in aqueous solutions, by using a linear polypeptide, poly(aspartic acid) (PAS), and a globular protein, bovine serum albumin (BSA), have been studied. The main interest was to identify the optimum conditions for an interpenetrated complex formation in order to design materials suitable for biomedical applications, such as drug delivery systems. BSA surface possesses several amino- and carboxylic groups available for covalent modification, and/or bioactive substances attachment. In the present study, mixtures between PAS and BSA were investigated at 37°C in dilute aqueous solution by viscometry, dynamic light scattering and zeta potential determination, as well as in solid state by AFM microscopy and dielectric spectroscopy. The experimental data have shown that the interpolymer complex formation occurs for a PAS/BSA molar ratio around 0.541.

  6. Application and appreciation of chemical sand fixing agent-poly (aspartic acid) and its composites

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun; Cao Hui; Wang Fang [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China); Tan Tianwei [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China)], E-mail: twtan@mail.buct.edu.cn

    2007-12-15

    The sand fixing agent-poly (aspartic acid) (PASP) and its composites were applied in the field by two forms (spraying around by PASP solution and PASP powder directly). It was found that the sand fixing effect in powder form was not as good as in solution form, but it was more practical in dry region. It needed 9, 6 and 7 days for PASP, xanthan gum-PASP (X2) and ethyl cellulose-PASP (E3) to attain the maximal mechanical strength after they were applied, respectively. The sand fixing effect decreased when the material was subjected to repeated hydration-dehydration cycles and the material had no negative influence on plant growth. The PASP and its composites had water-retaining ability and could reduce the water evaporation. - The sand fixing agent was applied in powder form and it had no negative influence on plant growth.

  7. Identification and Validation of Aspartic Acid Semialdehyde Dehydrogenase as a New Anti-Mycobacterium Tuberculosis Target.

    Science.gov (United States)

    Meng, Jianzhou; Yang, Yanhui; Xiao, Chunling; Guan, Yan; Hao, Xueqin; Deng, Qi; Lu, Zhongyang

    2015-09-30

    Aspartic acid semialdehyde dehydrogenase (ASADH) lies at the first branch point in the essential aspartic acid biosynthetic pathway that is found in bacteria and plants but is absent from animals. Mutations in the asadh gene encoding ASADH produce an inactive enzyme, which is lethal. Therefore, in this study, we investigated the hypothesis that ASADH represents a new anti-Mycobacterium tuberculosis (MTB) target. An asadh promoter-replacement mutant MTB, designated MTB::asadh, in which asadh gene expression is regulated by pristinamycin, was constructed to investigate the physiological functions of ASADH in the host bacteria. Bacterial growth was evaluated by monitoring OD600 and ASADH expression was analyzed by Western blotting. The results showed that the growth and survival of MTB::asadh was completely inhibited in the absence of the inducer pristinamycin. Furthermore, the growth of the mutant was rigorously dependent on the presence of the inducer in the medium. The starved mutant exhibited a marked reduction (approximately 80%) in the cell wall materials compared to the wild-type, in addition to obvious morphological differences that were apparent in scanning electron microscopy studies; however, with the addition of pristinamycin, the cell wall contents and morphology similar to those of the wild-type strain were recovered. The starved mutant also exhibited almost no pathogenicity in an in vitro model of infection using mouse macrophage J774A.1 cells. The mutant showed a concentration-dependent recovery of pathogenicity with the addition of the inducer. These findings implicate ASADH as a promising target for the development of novel anti-MTB drugs.

  8. Identification and Validation of Aspartic Acid Semialdehyde Dehydrogenase as a New Anti-Mycobacterium Tuberculosis Target

    Directory of Open Access Journals (Sweden)

    Jianzhou Meng

    2015-09-01

    Full Text Available Aspartic acid semialdehyde dehydrogenase (ASADH lies at the first branch point in the essential aspartic acid biosynthetic pathway that is found in bacteria and plants but is absent from animals. Mutations in the asadh gene encoding ASADH produce an inactive enzyme, which is lethal. Therefore, in this study, we investigated the hypothesis that ASADH represents a new anti-Mycobacterium tuberculosis (MTB target. An asadh promoter-replacement mutant MTB, designated MTB::asadh, in which asadh gene expression is regulated by pristinamycin, was constructed to investigate the physiological functions of ASADH in the host bacteria. Bacterial growth was evaluated by monitoring OD600 and ASADH expression was analyzed by Western blotting. The results showed that the growth and survival of MTB::asadh was completely inhibited in the absence of the inducer pristinamycin. Furthermore, the growth of the mutant was rigorously dependent on the presence of the inducer in the medium. The starved mutant exhibited a marked reduction (approximately 80% in the cell wall materials compared to the wild-type, in addition to obvious morphological differences that were apparent in scanning electron microscopy studies; however, with the addition of pristinamycin, the cell wall contents and morphology similar to those of the wild-type strain were recovered. The starved mutant also exhibited almost no pathogenicity in an in vitro model of infection using mouse macrophage J774A.1 cells. The mutant showed a concentration-dependent recovery of pathogenicity with the addition of the inducer. These findings implicate ASADH as a promising target for the development of novel anti-MTB drugs.

  9. Formation of haloacetamides during chlorination of dissolved organic nitrogen aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Chu Wenhai, E-mail: 1world1water@tongji.edu.cn [State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092 (China); Gao Naiyun [State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092 (China); Deng Yang, E-mail: yang.deng@upr.edu [Department of Civil Engineering and Surveying, University of Puerto Rico, P.O. Box 9041, Mayaguez, Puerto Rico, 00681-9041 (Puerto Rico)

    2010-01-15

    The stability of haloacetamides (HAcAms) such as dichloroacetamide (DCAcAm) and trichloroacetamide (TCAcAm) was studied under different experimental conditions. The yield of HAcAms during aspartic acid (Asp) chlorination was measured at different molar ratio of chlorine atom to nitrogen atom (Cl/N), pH and dissolved organic carbon (DOC) mainly consisted of humic acid (HA) mixture. Ascorbic acid showed a better capacity to prevent the decay of DCAcAm and TCAcAm than the other two dechlorinating agents, thiosulfate and sodium sulfite. Lower Cl/N favored the DCAcAm formation, implying that breakpoint chlorination might minimize its generation. The pH decrease could lower the concentration of DCAcAm but favored dichloroacetonitrile (DCAN) formation. DCAcAm yield was sensitive to the DOC due to higher chlorine consumption caused by HA mixture. Two possible pathways of DCAcAm formation during Asp chlorination were proposed. Asp was an important precursor of DCAN, DCAcAm and dichloroacetic acid (DCAA), and thus removal of Asp before disinfection may be a method to prevent the formation of DCAcAm, DCAN and DCAA.

  10. Probing the segmental mobility and energy of the active zones of a protein chain (aspartic acid protease) by a coarse-grained bond-fluctuation Monte Carlo simulation

    Science.gov (United States)

    Pandey, Ras; Farmer, Barry

    2008-03-01

    A protein chain such as aspartic acid protease is described by a specific sequence of 99 residues each with its own specific characteristics. In a coarse-grained description, the backbone of a protein chain is described by nodes tethered together by peptide bonds where each node (the amino acid group) is characterized by molecular weight and hydrophobicity. A well-developed and somewhat mature computational modeling tool for the polymer chain such as the bond-fluctuation model is used to study such a specific protein chain with its constitutive amino groups and their sequence. The relative magnitude of hydrophobicity is used to develop appropriate interaction potentials for these amino acid groups in explicit solvent. The Metropolis algorithm is used to move each node and solvent constituent. Local energy and mobility of each amino group are analyzed along with global energy, mobility, and conformation of the protein chain. Effect of the solvent interaction and its concentration on these quantities will be presented.

  11. Peptidyl prolyl isomerase Pin1-inhibitory activity of D-glutamic and D-aspartic acid derivatives bearing a cyclic aliphatic amine moiety.

    Science.gov (United States)

    Nakagawa, Hidehiko; Seike, Suguru; Sugimoto, Masatoshi; Ieda, Naoya; Kawaguchi, Mitsuyasu; Suzuki, Takayoshi; Miyata, Naoki

    2015-12-01

    Pin1 is a peptidyl prolyl isomerase that specifically catalyzes cis-trans isomerization of phosphorylated Thr/Ser-Pro peptide bonds in substrate proteins and peptides. Pin1 is involved in many important cellular processes, including cancer progression, so it is a potential target of cancer therapy. We designed and synthesized a novel series of Pin1 inhibitors based on a glutamic acid or aspartic acid scaffold bearing an aromatic moiety to provide a hydrophobic surface and a cyclic aliphatic amine moiety with affinity for the proline-binding site of Pin1. Glutamic acid derivatives bearing cycloalkylamino and phenylthiazole groups showed potent Pin1-inhibitory activity comparable with that of known inhibitor VER-1. The results indicate that steric interaction of the cyclic alkyl amine moiety with binding site residues plays a key role in enhancing Pin1-inhibitory activity.

  12. Two aspartate residues at the putative p10 subunit of a type II metacaspase from Nicotiana tabacum L. may contribute to the substrate-binding pocket.

    Science.gov (United States)

    Acosta-Maspons, Alexis; Sepúlveda-García, Edgar; Sánchez-Baldoquín, Laura; Marrero-Gutiérrez, Junier; Pons, Tirso; Rocha-Sosa, Mario; González, Lien

    2014-01-01

    Metacaspases are cysteine proteases present in plants, fungi, prokaryotes, and early branching eukaryotes, although a detailed description of their cellular function remains unclear. Currently, three-dimensional (3D) structures are only available for two metacaspases: Trypanosoma brucei (MCA2) and Saccharomyces cerevisiae (Yca1). Furthermore, metacaspases diverged from animal caspases of known structure, which limits straightforward homology-based interpretation of functional data. We report for the first time the identification and initial characterization of a metacaspase of Nicotiana tabacum L., NtMC1. By combining domain search, multiple sequence alignment (MSA), and protein fold-recognition studies, we provide compelling evidences that NtMC1 is a plant metacaspase type II, and predict its 3D structure using the crystal structure of two type I metacaspases (MCA2 and Yca1) and Gsu0716 protein from Geobacter sulfurreducens as template. Analysis of the predicted 3D structure allows us to propose Asp353, at the putative p10 subunit, as a new member of the aspartic acid triad that coordinates the P1 arginine/lysine residue of the substrate. Nevertheless, site-directed mutagenesis and expression analysis in bacteria and Nicotiana benthamiana indicate the functionality of both Asp348 and Asp353. Through the co-expression of mutant and wild-type proteins by transient expression in N. benthamiana leaves we found that polypeptide processing seems to be intramolecular. Our results provide the first evidence in plant metacaspases concerning the functionality of the putative p10 subunit.

  13. Optical absorption and DFT calculations in L-aspartic acid anhydrous crystals: Charge carrier effective masses point to semiconducting behavior

    Science.gov (United States)

    Silva, A. M.; Silva, B. P.; Sales, F. A. M.; Freire, V. N.; Moreira, E.; Fulco, U. L.; Albuquerque, E. L.; Maia, F. F., Jr.; Caetano, E. W. S.

    2012-11-01

    Density functional theory (DFT) computations within the local-density approximation and generalized gradient approximation in pure form and with dispersion correction (GGA+D) were carried out to investigate the structural, electronic, and optical properties of L-aspartic acid anhydrous crystals. The electronic (band structure and density of states) and optical absorption properties were used to interpret the light absorption measurements we have performed in L-aspartic acid anhydrous crystalline powder at room temperature. We show the important role of the layered spatial disposition of L-aspartic acid molecules in anhydrous L-aspartic crystals to explain the observed electronic and optical properties. There is good agreement between the GGA+D calculated and experimental lattice parameters, with (Δa, Δb, Δc) deviations of (0.029,-0.023,-0.024) (units in Å). Mulliken [J. Chem. Phys.JCPSA60021-960610.1063/1.1740588 23, 1833 (1955)] and Hirshfeld [Theor. Chim. ActaTCHAAM0040-574410.1007/BF00549096 44, 129 (1977)] population analyses were also performed to assess the degree of charge polarization in the zwitterion state of the L-aspartic acid molecules in the DFT converged crystal. The lowest-energy optical absorption peaks related to transitions between the top of the valence band and the bottom of the conduction band involve O 2p valence states and C 1p and O 2p conduction states, with the carboxyl and COOH lateral chain group contributing significantly to the energy band gap. Among the calculated band gaps, the lowest GGA+D (4.49-eV) gap is smaller than the experimental estimate of 5.02 eV, as obtained by optical absorption. Such a wide-band-gap energy together with the small carrier effective masses estimated from band curvatures allows us to suggest that an L-aspartic acid anhydrous crystal can behave as a wide-gap semiconductor. A comparison of effective masses among directions parallel and perpendicular to the L-aspartic molecules layers reveals that charge

  14. Conserved aspartate and lysine residues of RcsB are required for amylovoran biosynthesis, virulence, and DNA binding in Erwinia amylovora.

    Science.gov (United States)

    Ancona, Veronica; Chatnaparat, Tiyakhon; Zhao, Youfu

    2015-08-01

    In Erwinia amylovora, the Rcs phosphorelay system is essential for amylovoran production and virulence. To further understand the role of conserved aspartate residue (D56) in the phosphor receiver (PR) domain and lysine (K180) residue in the function domain of RcsB, amino acid substitutions of RcsB mutant alleles were generated by site-directed mutagenesis and complementation of various rcs mutants were performed. A D56E substitution of RcsB, which mimics the phosphorylation state of RcsB, complemented the rcsB mutant, resulting in increased amylovoran production and gene expression, reduced swarming motility, and restored pathogenicity. In contrast, D56N and K180A or K180Q substitutions of RcsB did not complement the rcsB mutant. Electrophoresis mobility shift assays showed that D56E, but not D56N, K180Q and K180A substitutions of RcsB bound to promoters of amsG and flhD, indicating that both D56 and K180 are required for DNA binding. Interestingly, the RcsBD56E allele could also complement rcsAB, rcsBC and rcsABCD mutants with restored virulence and increased amylovoran production, indicating that RcsB phosphorylation is essential for virulence of E. amylovora. In addition, mutations of T904 and A905, but not phosphorylation mimic mutation of D876 in the PR domain of RcsC, constitutively activate the Rcs system, suggesting that phosphor transfer is required for activating the Rcs system and indicating both A905 and T904 are required for the phosphatase activity of RcsC. Our results demonstrated that RcsB phosphorylation and dephosphorylation, phosphor transfer from RcsC are essential for the function of the Rcs system, and also suggested that constitutive activation of the Rcs system could reduce the fitness of E. amylovora.

  15. Antagonizing Effects of Aspartic Acid against Ultraviolet A-Induced Downregulation of the Stemness of Human Adipose Tissue-Derived Mesenchymal Stem Cells.

    Directory of Open Access Journals (Sweden)

    Kwangseon Jung

    Full Text Available Ultraviolet A (UVA irradiation is responsible for a variety of changes in cell biology. The purpose of this study was to investigate effects of aspartic acid on UVA irradiation-induced damages in the stemness properties of human adipose tissue-derived mesenchymal stem cells (hAMSCs. Furthermore, we elucidated the UVA-antagonizing mechanisms of aspartic acid. The results of this study showed that aspartic acid attenuated the UVA-induced reduction of the proliferative potential and stemness of hAMSCs, as evidenced by increased proliferative activity in the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay and upregulation of stemness-related genes OCT4, NANOG, and SOX2 in response to the aspartic acid treatment. UVA-induced reduction in the mRNA level of hypoxia-inducible factor (HIF-1α was also significantly recovered by aspartic acid. In addition, the antagonizing effects of aspartic acid against the UVA effects were found to be mediated by reduced production of PGE2 through the inhibition of JNK and p42/44 MAPK. Taken together, these findings show that aspartic acid improves reduced stemness of hAMSCs induced by UVA and its effects are mediated by upregulation of HIF-1α via the inhibition of PGE2-cAMP signaling. In addition, aspartic acid may be used as an antagonizing agent to mitigate the effects of UVA.

  16. Antagonizing Effects of Aspartic Acid against Ultraviolet A-Induced Downregulation of the Stemness of Human Adipose Tissue-Derived Mesenchymal Stem Cells.

    Science.gov (United States)

    Jung, Kwangseon; Cho, Jae Youl; Soh, Young-Jin; Lee, Jienny; Shin, Seoung Woo; Jang, Sunghee; Jung, Eunsun; Kim, Min Hee; Lee, Jongsung

    2015-01-01

    Ultraviolet A (UVA) irradiation is responsible for a variety of changes in cell biology. The purpose of this study was to investigate effects of aspartic acid on UVA irradiation-induced damages in the stemness properties of human adipose tissue-derived mesenchymal stem cells (hAMSCs). Furthermore, we elucidated the UVA-antagonizing mechanisms of aspartic acid. The results of this study showed that aspartic acid attenuated the UVA-induced reduction of the proliferative potential and stemness of hAMSCs, as evidenced by increased proliferative activity in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and upregulation of stemness-related genes OCT4, NANOG, and SOX2 in response to the aspartic acid treatment. UVA-induced reduction in the mRNA level of hypoxia-inducible factor (HIF)-1α was also significantly recovered by aspartic acid. In addition, the antagonizing effects of aspartic acid against the UVA effects were found to be mediated by reduced production of PGE2 through the inhibition of JNK and p42/44 MAPK. Taken together, these findings show that aspartic acid improves reduced stemness of hAMSCs induced by UVA and its effects are mediated by upregulation of HIF-1α via the inhibition of PGE2-cAMP signaling. In addition, aspartic acid may be used as an antagonizing agent to mitigate the effects of UVA.

  17. 热缩催化聚合合成聚天冬氨酸%SYNTHESIS OF POLY-ASPARTIC ACID BY PYROCONDENSATION CATALYZE POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    陶敬奇; 李景宁; 王广洪; 曾广益

    2004-01-01

    The Polysuccinimide is Synthesized by means of pyrocondensation catalyze polymerization,using L-aspartic acid as a monomer.Poly-aspartic Acid is achieved by hydrolization of Polysuccinimide.The effect of temperature,time,catalyzer and condition of hydrolization on yield and quality is studied.The research results show that the method has the advantages of simple equipment and high yield.

  18. Influence of step faceting on the enantiospecific decomposition of aspartic acid on chiral Cu surfaces vicinal to Cu{111}.

    Science.gov (United States)

    Reinicker, A D; Therrien, A J; Lawton, T J; Ali, R; Sykes, E C H; Gellman, A J

    2016-09-13

    On surfaces vicinal to Cu{111}, l-aspartic acid (l-Asp) adsorption causes steps to facet enantiospecifically into {310}(R) and {320}(S) steps. l-Asp has its highest heat of adsortion on surfaces that naturally expose the {310}(R) or {320}(S) steps but decomposes preferentially on the {310}(R) steps.

  19. Collagen turnover in normal and degenerate human intervertebral discs as determined by the racemization of aspartic acid

    NARCIS (Netherlands)

    Sivan, S.-S.; Wachtel, E.; Tsitron, E.; Sakkee, N.; Ham, F. van der; Groot, J.de; Roberts, S.; Maroudas, A.

    2008-01-01

    Knowledge of rates of protein turnover is important for a quantitative understanding of tissue synthesis and catabolism. In this work, we have used the racemization of aspartic acid as a marker for the turnover of collagen obtained from healthy and pathological human intervertebral disc matrices. We

  20. Aspartic acid based nucleoside phosphoramidate prodrugs as potent inhibitors of hepatitis C virus replication.

    Science.gov (United States)

    Maiti, Munmun; Maiti, Mohitosh; Rozenski, Jef; De Jonghe, Steven; Herdewijn, Piet

    2015-05-14

    In view of a persistent threat to mankind, the development of nucleotide-based prodrugs against hepatitis C virus (HCV) is considered as a constant effort in many medicinal chemistry groups. In an attempt to identify novel nucleoside phosphoramidate analogues for improving the anti-HCV activity, we have explored, for the first time, aspartic acid (Asp) and iminodiacetic acid (IDA) esters as amidate counterparts by considering three 2'-C-methyl containing nucleosides, 2'-C-Me-cytidine, 2'-C-Me-uridine and 2'-C-Me-2'-fluoro-uridine. Synthesis of these analogues required protection for the vicinal diol functionality of the sugar moiety and the amino group of the cytidine nucleoside to regioselectively perform phosphorylation reaction at the 5'-hydroxyl group. Anti-HCV data demonstrate that the Asp-based phosphoramidates are ∼550 fold more potent than the parent nucleosides. The inhibitory activity of the Asp-ProTides was higher than the Ala-ProTides, suggesting that Asp would be a potential amino acid candidate to be considered for developing novel antiviral prodrugs.

  1. Aspartic acid concentrations in coral skeletons as recorders of past disturbances of metabolic rates

    Science.gov (United States)

    Gupta, Lallan P.; Suzuki, Atsushi; Kawahata, Hodaka

    2006-11-01

    The composition of total hydrolysable amino acids (THAAs) in a skeleton of the coral Porites australiensis, collected from Ishigaki Island, Japan, was examined in order to determine whether amino acids (AA) can be used as biomarkers of past changes in coral physiology (metabolism). Micro-samples, corresponding to a time resolution of 1 month, were collected along the growth axis of the coral. Of the 20 AAs analyzed, aspartic acid (Asp) was the most abundant, and its mole concentration relative to the sum of all other AAs (mole%Asp) showed a clear seasonal pattern of low content during winters and high during summers. A growth disturbance in the coral skeleton during 1988 1990, shown by X-ray scans and oxygen and carbon stable isotope data, was marked by a high mole%Asp ratio. Variability in carbon isotope data has often been attributed to metabolic effects, or changes in the isotopic composition of seawater, or both. The changes in mole%Asp shown here suggest that metabolic effects are mainly responsible for sharp changes in carbon isotope profiles during periods of growth disturbance.

  2. Metabolic pathways and fermentative production of L-aspartate family amino acids.

    Science.gov (United States)

    Park, Jin Hwan; Lee, Sang Yup

    2010-06-01

    The L-aspartate family amino acids (AFAAs), L-threonine, L-lysine, L-methionine and L-isoleucine have recently been of much interest due to their wide spectrum of applications including food additives, components of cosmetics and therapeutic agents, and animal feed additives. Among them, L-threonine, L-lysine and L-methionine are three major amino acids produced currently throughout the world. Recent advances in systems metabolic engineering, which combine various high-throughput omics technologies and computational analysis, are now facilitating development of microbial strains efficiently producing AFAAs. Thus, a thorough understanding of the metabolic and regulatory mechanisms of the biosynthesis of these amino acids is urgently needed for designing system-wide metabolic engineering strategies. Here we review the details of AFAA biosynthetic pathways, regulations involved, and export and transport systems, and provide general strategies for successful metabolic engineering along with relevant examples. Finally, perspectives of systems metabolic engineering for developing AFAA overproducers are suggested with selected exemplary studies.

  3. A rapid and sensitive detection of D-Aspartic acid in Crystallin by chiral derivatized liquid chromatography mass spectrometry.

    Science.gov (United States)

    Mizuno, Hajime; Miyazaki, Yasuto; Ito, Keisuke; Todoroki, Kenichiro; Min, Jun Zhe; Toyo'oka, Toshimasa

    2016-10-07

    A method for the determination of D-Aspartic acid (D-Asp) and its D/L ratio in peptides and proteins has been developed. This method was carried out with good separation of the D/L chiral peptide pairs by combination of a chiral derivatization and an ADME column separation. Furthermore, a cationic derivatization reagent, DBD-Py-NCS, increased the sensitivity of the ESI-MS/MS detection. To confirm the comprehensive peptide analysis, synthesized α-Crystallin tryptic peptides, which included D-Asp residues, were analyzed. The 5 pairs of D/L-Asp that included peptide diastereomers were well separated. Their peak resolutions were more than 1.5 and the results were reproducible (RSD<0.05, n=5). As an application of this method, we analyzed the α-Crystallin standard and UV irradiated α-Crystallin. After trypsin digestion and DBD-Py-NCS derivatization, the tryptic peptide derivatives were applied to LC-MS/MS. Based on the results of peptide sequence identification, almost all the tryptic peptides of the αA- and αB-Crystallin homologous subunits of α-Crystallin were detected as DBD-Py NCS derivatives. However, there was no D-Asp residue in the standard proteins. In the case of the UV irradiated α-Crystallin, Asp(76) and Asp(84) in the αA-Crystallin and Asp(96) in αB-Crystallin were racemized to D-Asp. These results show that this proposed chiral peptide LC-MS/MS method using chiral derivatization provides a rapid and sensitive analysis for post translational Asp racemization sites in aging proteins.

  4. A route to anionic hydrophilic films of copolymers of l-leucine, l-aspartic acid and l-aspartic acid esters

    NARCIS (Netherlands)

    Sederel, W.L.; Bantjes, A.; Feijen, J.

    1975-01-01

    A series of copolymers of l-leucine and β-benzyl-l-aspartate [Leu/Asp(OBz)] covering the range 30–70 mol % of l-leucine, was synthesized by the N-carboxyanhydride (NCA) method. The copolymers were characterized by elemental analysis, infra-red spectroscopy and viscometry. For all compositions high m

  5. Substitution of a single amino acid (aspartic acid for histidine) converts the functional activity of human complement C4B to C4A

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, M.C.; Fathallah, D.M.; Bergamaschini, L.; Alicot, E.M. (Harvard Medical School, Boston, MA (USA)); Isenman, D.E. (Univ. of Toronto, Ontario (Canada))

    1990-09-01

    The C4B isotype of the fourth component of human complement (C4) displays 3- to 4-fold greater hemolytic activity than does its other isotype C4A. This correlates with differences in their covalent binding efficiencies to erythrocytes coated with antibody and complement C1. C4A binds to a greater extent when C1 is on IgG immune aggregates. The differences in covalent binding properties correlate only with amino acid changes between residues 1101 and 1106 (pro-C4 numbering)-namely, Pro-1101, Cys-1102, Leu-1105, and Asp-1106 in C4A and Leu-1101, Ser-1102, Ile-1105, and His-1106 in C4B, which are located in the C4d region of the {alpha} chain. To more precisely identify the residues that are important for the functional differences, C4A-C4B hybrid proteins were constructed by using recombinant DNA techniques. Comparison of these by hemolytic assay and binding to IgG aggregates showed that the single substitution of aspartic acid for histidine at position 1106 largely accounted for the change in functional activity and nature of the chemical bond formed. Surprisingly, substitution of a neutral residue, alanine, for histidine at position 1106 resulted in an increase in binding to immune aggregates without subsequent reduction in the hemolytic activity. This result strongly suggests that position 1106 is not catalytic as previously proposed but interacts sterically/electrostatically with potential acceptor sites and serves to select binding sites on potential acceptor molecules.

  6. DL-天冬氨酸的绿色合成%Green Synthesis and Characterization of DL-Aspartic Acid

    Institute of Scientific and Technical Information of China (English)

    崔建兰; 徐春彦; 曹端林

    2003-01-01

      The process of synthesizing DL-Aspartic acid with maleic acid and ammonia as raw materials was improved in this paper. It realizes the green synthesis at a low cost and less pollution, when maleic acid was used instead of traditional hydrochloric acid in the acidification process. The yield of DL-Aspartic acid was up to 75% above and purity 98.9%. The product DL-Aspartic acid was characterized by IR, the amino-acid automatic analyzing instrument, nuclear magnetic resonance.%  本文对以顺丁烯二酸与氨水为原料合成DL-天冬氨酸的方法进行了改进,在酸化后处理过程中,以顺丁烯二酸代替传统的盐酸,反应平均收率提高到75%以上,纯度达98.9%,实现了绿色合成,减少了污染,降低了成本,并通过红外光谱、核磁共振、氨基酸自动分析仪等对产品进行了表征.

  7. Adaptation of human immunodeficiency virus type 1 to cells expressing a binding-deficient CD4 mutant (lysine 46 to aspartic acid).

    Science.gov (United States)

    Choe, H R; Sodroski, J

    1995-01-01

    Human immunodeficiency virus (HIV-1) was adapted to replicate efficiently in cells expressing an altered form of the CD4 viral receptor. The mutant CD4 (46 K/D) contained a single amino acid change (lysine 46 to aspartic acid) in the CDR2 loop of domain 1, which results in a 15-fold reduction in affinity for the viral gp120 glycoprotein. The ability of the adapted virus to replicate in CD4 46 K/D-expressing cells was independently enhanced by single amino acid changes in the V2 variable loop, the V3 variable loop, and the fourth conserved (C4) region of the gp120 glycoprotein. Combinations of these amino acids in the same envelope glycoprotein resulted in additive enhancement of virus replication in cells expressing the CD4 46 K/D molecule. In cells expressing the wild-type CD4 glycoproteins, the same V2 and V3 residue changes also increased the efficiency of replication of a virus exhibiting decreased receptor-binding ability due to an amino acid change (aspartic acid 368 to glutamic acid) in the gp120 glycoprotein. In neither instance did the adaptive changes restore the binding ability of the monomeric gp120 glycoprotein or the oligomeric envelope glycoprotein complex for the mutant or wild-type CD4 glycoproteins, respectively. Thus, particular conformations of the gp120 V2 and V3 variable loops and of the C4 region allow postreceptor binding events in the membrane fusion process to occur in the context of less than optimal receptor binding. These results suggest that the fusion-related functions of the V2, V3, and C4 regions of gp120 are modulated by CD4 binding. PMID:7707502

  8. Comparison of Dissolution and Surface Reactions Between Calcite and Aragonite in L-Glutamic and L-Aspartic Acid Solutions

    Directory of Open Access Journals (Sweden)

    Kwangsuk You

    2010-01-01

    Full Text Available We have investigated dissolution and surface reaction of calcite and aragonite in amino acid solutions of L-glutamic (L-glu and L-aspartic acid (L-asp at weak acidity of above pH 3. The surface reactions of calcite and aragonite were related with the dissolution. Calcite was dissolved in both solutions but the dissolution was limited by an adsorption of Ca-carboxylate salt. Aragonite was neither dissolved nor reacted in amino acid solutions because the crystal surface consisted of a hard to dissolve structure.

  9. Terbium-Aspartic Acid Nanocrystals with Chirality-Dependent Tunable Fluorescent Properties.

    Science.gov (United States)

    Ma, Baojin; Wu, Yu; Zhang, Shan; Wang, Shicai; Qiu, Jichuan; Zhao, Lili; Guo, Daidong; Duan, Jiazhi; Sang, Yuanhua; Li, Linlin; Jiang, Huaidong; Liu, Hong

    2017-02-28

    Terbium-aspartic acid (Tb-Asp) nanocrystals with chirality-dependent tunable fluorescent properties can be synthesized through a facile synthesis method through the coordination between Tb and Asp. Asp with different chirality (dextrorotation/d and levogyration/l) changes the stability of the coordination center following fluorescent absorption/emission ability differences. Compared with l-Asp, d-Asp can coordinate Tb to form a more stable center, following the higher quantum yield and longer fluorescence life. Fluorescence intensity of Tb-Asp linearly increases with increase ratio of d-Asp in the mixed chirality Tb-Asp system, and the fluorescent properties of Tb-Asp nanocrystals can be tuned by adjusting the chirality ratio. Tb-Asp nanocrystals possess many advantage, such as high biocompatibility, without any color in visible light irradiation, monodispersion with very small size, and long fluorescent life. Those characteristics will give them great potential in many application fields, such as low-cost antifake markers and advertisements using inkjet printers or for molds when dispersed in polydimethylsiloxane. In addition, europium can also be used to synthesize Eu-Asp nanoparticles. Importantly, the facile, low-cost, high-yield, mass-productive "green" process provides enormous advantages for synthesis and application of fluorescent nanocrystals, which will have great impact in nanomaterial technology.

  10. Finding a Leucine in a Haystack: Searching the Proteome for ambigous Leucine-Aspartic Acid motifs

    KAUST Repository

    Arold, Stefan T.

    2016-01-25

    Leucine-aspartic acid (LD) motifs are short helical protein-protein interaction motifs involved in cell motility, survival and communication. LD motif interactions are also implicated in cancer metastasis and are targeted by several viruses. LD motifs are notoriously difficult to detect because sequence pattern searches lead to an excessively high number of false positives. Hence, despite 20 years of research, only six LD motif–containing proteins are known in humans, three of which are close homologues of the paxillin family. To enable the proteome-wide discovery of LD motifs, we developed LD Motif Finder (LDMF), a web tool based on machine learning that combines sequence information with structural predictions to detect LD motifs with high accuracy. LDMF predicted 13 new LD motifs in humans. Using biophysical assays, we experimentally confirmed in vitro interactions for four novel LD motif proteins. Thus, LDMF allows proteome-wide discovery of LD motifs, despite a highly ambiguous sequence pattern. Functional implications will be discussed.

  11. Reactions of Cr3+ with aspartic acid within a wide pH range

    Directory of Open Access Journals (Sweden)

    Yahia Z. Hamada

    2014-12-01

    Full Text Available Formation of the metal complexes of aspartic acid (Asp with the chromium metal ion (Cr3+ in solutions using potentiometric titrations is presented within a wide pH range (∼3.5 to ∼10.5 at 25°C and I=0.10 M NaNO3. Concentration distribution diagrams revealed that the main complex formed within this pH range is the bis Cr 3+ complex. Literature stability constant values for the Cr–Asp complexes were used to construct concentration distribution diagrams. Complexes taken into consideration were the simple one-to-one complex, the bis-complex, and the bis-mono-protonated complex, namely, Cr–Asp, Cr(Asp2, and Cr(Asp2H. The corresponding Log β values of these complexes were 12.46, 21.86, and 24.30, respectively. UV–Vis spectra demonstrate Cr 3+–Asp binding. The UV–Vis spectra were collected from a system that reached a high level of equilibrium state (50 days’ equilibrium time.

  12. Evaluation of poly (aspartic acid sodium salt) as a draw solute for forward osmosis.

    Science.gov (United States)

    Gwak, Gimun; Jung, Bokyung; Han, Sungsoo; Hong, Seungkwan

    2015-09-01

    Poly (aspartic acid sodium salt) (PAspNa) was evaluated for its potential as a novel draw solute in forward osmosis (FO). The inherent advantages of PAspNa, such as good water solubility, high osmotic pressure, and nontoxicity, were first examined through a series of physicochemical analyses and atomic-scale molecular dynamics simulations. Then, lab-scale FO tests were performed to evaluate its suitability in practical processes. Compared to other conventional inorganic solutes, PAspNa showed comparable water flux but significantly lower reverse solute flux, demonstrating its suitability as a draw solute. Moreover, fouling experiments using synthetic wastewater as a feed solution demonstrated that PAspNa reversely flowed to the feed side reduced inorganic scaling on the membrane active layer. The recyclability of PAspNa was studied using both nanofiltration (NF) and membrane distillation (MD) processes, and the results exhibited its ease of recovery. This research reported the feasibility and applicability of FO-NF or FO-MD processes using PAspNa for wastewater reclamation and brackish water desalination.

  13. Aspartic acid racemization dating of Holocene brachiopods and bivalves from the southern Brazilian shelf, South Atlantic

    Science.gov (United States)

    Barbour Wood, Susan L.; Krause, Richard A.; Kowalewski, Michał; Wehmiller, John; Simões, Marcello G.

    2006-09-01

    The extent of racemization of aspartic acid (Asp) has been used to estimate the ages of 9 shells of the epifaunal calcitic brachiopod Bouchardia rosea and 9 shells of the infaunal aragonitic bivalve Semele casali. Both taxa were collected concurrently from the same sites at depths of 10 m and 30 m off the coast of Brazil. Asp D/L values show an excellent correlation with radiocarbon age at both sites and for both taxa ( r2Site 9 B. rosea = 0.97, r2Site 1 B. rosea = 0.997, r2Site 9 S. casali = 0.9998, r2Site 1 S. casali = 0.93). The Asp ratios plotted against reservoir-corrected AMS radiocarbon ages over the time span of multiple millennia can thus be used to develop reliable and precise geochronologies not only for aragonitic mollusks (widely used for dating previously), but also for calcitic brachiopods. At each collection site, Bouchardia specimens display consistently higher D/L values than specimens of Semele. Thermal differences between sites are also notable and in agreement with theoretical expectations, as extents of racemization for both taxa are greater at the warmer, shallower site than at the cooler, deeper one. In late Holocene marine settings, concurrent time series of aragonitic and calcitic shells can be assembled using Asp racemization dating, and parallel multi-centennial to multi-millennial records can be developed simultaneously for multiple biomineral systems.

  14. Biphasic effects of ethanol and sodium oleate on synaptic transport of aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Foley, T.; Rhoads, D.E.

    1987-05-01

    The authors have examined the effects of ethanol and sodium oleate on the transport of aspartic acid (ASP) by nerve-ending preparations from rat cerebral cortex. Physiologically relevant ethanol concentrations of up to 100mM stimulated ASP uptake while concentrations greater than 200mM caused inhibition. A similar biphasic effect was observed with oleate stimulating ASP uptake at 0.1 to 1..mu..M and inhibiting ASP uptake at concentrations greater than 1..mu..M. Maximum stimulation was observed at 0.1..mu..M oleate and at 50mM ethanol. In contrast, when synaptosomes were prepared from rats that had been exposed for 2-3 weeks to 10% ethanol in their drinking water, higher concentrations of ethanol and oleate were required to obtain comparable stimulation of ASP uptake. These biphasic effects on ASP transport can be interpreted in terms of physicochemical alterations in the synaptic membranes, with from alcohol-exposed rats showing tolerance to these fluidizing effects.

  15. Inactivation of cystein-aspartic acid protease (caspase)-1 by saikosaponin A.

    Science.gov (United States)

    Han, Na-Ra; Kim, Hyung-Min; Jeong, Hyun-Ja

    2011-01-01

    This work investigates the anti-inflammatory mechanism of saikosaponin A (SA), a major component of Bupleurum falcatum LINNE. SA significantly inhibited phorbol myristate acetate (PMA) plus A23187-induced the production and expression of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in human mast cell (HMC)-1 cells. SA suppressed PMA plus A23187-induced phosphorylation of extracellular signal-regulated kinase and p38. When HMC-1 cells were treated with SA, translocation of nuclear factor (NF)-κB/Rel A into nucleus and degradation of inhibitor of NF-κB (IκB) in cytoplasm were inhibited. SA decreased PMA plus A23187-induced cysteine-aspartic acid protease (caspase)-1 activity. IL-1β production was also inhibited by SA. Finally, SA significantly decreased the number of nasal rubs and serum TNF-α level in the ovalbumin-sensitized allergic rhinitis mouse model. The underlying mechanism involves, at least in part, inactivation of caspase-1, which provides new evidence for therapeutic application of SA to target inflammatory processes.

  16. The putative effects of D-Aspartic acid on blood testosterone levels: A systematic review

    Science.gov (United States)

    Roshanzamir, Farzad; Safavi, Seyyed Morteza

    2017-01-01

    Background: D-Aspartic acid (D-Asp) is in invertebrate and vertebrate neuroendocrine tissues, where it carries out important physiological functions. Recently, it has been reported that D-Asp is involved in the synthesis and release of testosterone and is assumed can be used as a testosterone booster for infertile men, and by athletes to increase muscle mass and strength. Objective: The aim of this review is to summarize available evidence related to the effects of D-Asp on serum testosterone levels. Materials and Methods: We conducted a systematic review of all type studies, which evaluated the effect of the D-Asp on blood testosterone including published papers until October 2015, using PubMed, ISI Web of Science, ProQuest and Scopus database. Results: With 396 retrieved records, 23 animal studies and 4 human studies were included. In vivo and in vitro animal studies revealed the effect of D-Asp depending on species, sex and organ-specific. Our results showed that exogenous D-Asp enhances testosterone levels in male animal’s studies, whereas studies in human yielded inconsistent results. The evidence for this association in man is still sparse, mostly because of limited number and poor quality studies. Conclusion: There is an urgent need for more and well-designed human clinical trials with larger sample sizes and longer duration to investigate putative effects of D-Asp on testosterone concentrations. PMID:28280794

  17. Aspartic acid functions as carbonyl trapper to inhibit the formation of advanced glycation end products by chemical chaperone activity.

    Science.gov (United States)

    Prasanna, Govindarajan; Saraswathi, N T

    2016-05-01

    Advanced glycation end products (AGEs) were implicated in pathology of numerous diseases. In this study, we present the bioactivity of aspartic acid (Asp) to inhibit the AGEs. Hemoglobin and bovine serum albumin (BSA) were glycated with glucose, fructose, and ribose in the presence and absence of Asp (100-200 μM). HbA1c inhibition was investigated using human blood and characterized by micro-column ion exchange chromatography. The effect of methyl glyoxal (MG) on hemoglobin and BSA was evaluated by fluorescence spectroscopy and gel electrophoresis. The effect of MG on red blood cells morphology was characterized by scanning electron micrographs. Molecular docking was performed on BSA with Asp. Asp is capable of inhibiting the formation of fluorescent AGEs by reacting with the reducing sugars. The presence of Asp as supplement in whole blood reduced the HbA1c% from 8.8 to 6.1. The presence of MG showed an increase in fluorescence and the presence of Asp inhibited the glycation thereby the fluorescence was quenched. MG also affected the electrophoretic mobility of hemoglobin and BSA by forming high molecular weight aggregates. Normal RBCs showed typical biconcave shape. MG modified RBCs showed twisted and elongated shape whereas the presence of ASP tends to protect RBC from twisting. Asp interacted with arginine residues of bovine serum albumin particularly ARG 194, ARG 198, and ARG 217 thereby stabilized the protein complex. We conclude that Asp has dual functions as a chemical chaperone to stabilize protein and as a dicarbonyl trapper, and thereby it can prevent the complications caused by glycation.

  18. Measurement of aspartic acid in oilseed rape leaves under herbicide stress using near infrared spectroscopy and chemometrics

    Directory of Open Access Journals (Sweden)

    Chu Zhang

    2016-01-01

    Full Text Available Oilseed rape is used as both food and a renewable energy resource. Physiological parameters, such as the amino acid aspartic acid, can indicate the growth status of oilseed rape. Traditional detection methods are laborious, time consuming, costly, and not usable in the field. Here, we investigate near infrared spectroscopy (NIRS as a fast and non-destructive detection method of aspartic acid in oilseed rape leaves under herbicide stress. Different spectral pre-processing methods were compared for optimal prediction performance. The variable selection methods were applied for relevant variable selection, including successive projections algorithm (SPA, Monte Carlo-uninformative variable elimination (MC-UVE and random frog (RF. The selected effective wavelengths (EWs were used as input by multiple linear regression (MLR, partial least squares (PLS and least-square support vector machine (LS-SVM. The best predictive performance was achieved by SPA-LS-SVM (Raw model using 22 EWs, and the prediction results were Rp = 0.9962 and RMSEP = 0.0339 for the prediction set. The result indicated that NIR combined with LS-SVM is a powerful new method to detect aspartic acid in oilseed rape leaves under herbicide stress.

  19. Measurement of aspartic acid in oilseed rape leaves under herbicide stress using near infrared spectroscopy and chemometrics.

    Science.gov (United States)

    Zhang, Chu; Kong, Wenwen; Liu, Fei; He, Yong

    2016-01-01

    Oilseed rape is used as both food and a renewable energy resource. Physiological parameters, such as the amino acid aspartic acid, can indicate the growth status of oilseed rape. Traditional detection methods are laborious, time consuming, costly, and not usable in the field. Here, we investigate near infrared spectroscopy (NIRS) as a fast and non-destructive detection method of aspartic acid in oilseed rape leaves under herbicide stress. Different spectral pre-processing methods were compared for optimal prediction performance. The variable selection methods were applied for relevant variable selection, including successive projections algorithm (SPA), Monte Carlo-uninformative variable elimination (MC-UVE) and random frog (RF). The selected effective wavelengths (EWs) were used as input by multiple linear regression (MLR), partial least squares (PLS) and least-square support vector machine (LS-SVM). The best predictive performance was achieved by SPA-LS-SVM (Raw) model using 22 EWs, and the prediction results were Rp = 0.9962 and RMSEP = 0.0339 for the prediction set. The result indicated that NIR combined with LS-SVM is a powerful new method to detect aspartic acid in oilseed rape leaves under herbicide stress.

  20. Computational study on 3D structure of L-aspartic acid and L-glutamic acid: molecular descriptors and properties

    Directory of Open Access Journals (Sweden)

    Stefaniu Amalia

    2016-06-01

    Full Text Available The aim of this work is to provide a comprehensive and complex analysis of molecular descriptors and properties of two similar amino acids, L-Aspartic acid and L-Glutamic acid, using a software tool for calculations and properties predictions. As amino acids are model compounds for predicting the physical-chemical properties and behavior of biological, larger molecules as peptides or proteins, researches were focused on providing accurate mechanical calculations using: molecular/mechanical methods. Our study aims to initiate a linear scaling approach, by dividing a large system into small subsystems and performing the calculations for each, individually, then, embedding and correcting the information globally. The calculations were performed on the 3D structure of the studied amino acids that were first generated, as CPK model, and optimized by energy minimization. A comparative assay on their topological, molecular descriptors and properties was conducted, in vacuum and in water, using the Hartree-Fock model and second-order Møller-Plesset perturbation theory MP2 for predicting structure, energy and property calculations with Spartan’14 software. Values of molecular properties such as area, volume, polar surface area, polarizability, ovality, logP, dipole moment, HOMO-LUMO gap, distances and angles between atoms, were obtained. The results have been interpreted in terms of electronic effects of side chain groups, molecular deformability, steric factors and reactivity. This approach can be extended to other amino acids in order to predict protein-ligand interactions, important aspects in drug design studies and protein engineering.

  1. Adsorption of L-glutamic acid and L-aspartic acid to γ-Al2O3

    Science.gov (United States)

    Greiner, Edward; Kumar, Kartik; Sumit, Madhuresh; Giuffre, Anthony; Zhao, Weilong; Pedersen, Joel; Sahai, Nita

    2014-05-01

    The interactions of amino acids with mineral surfaces have potential relevance for processes ranging from pre-biotic chemistry to biomineralization to protein adsorption on biomedical implants in vivo. Here, we report the results of experiments investigating the adsorption of L-glutamic (Glu) and L-aspartic (Asp) acids to γ-Al2O3. We examined the extent of Glu and Asp coverage as a function of pH and solution concentration (pH edges and isotherms) in solution-depletion experiments and used in situ Attenuated Total Refkectance Fourier Transform Infrared (ATR-FTIR) spectroscopy to estimate the molecular conformations of the adsorbed molecules. Glu and Asp exhibited similar adsorption behavior on γ-Al2O3 with respect to pH and solution concentration. In general, adsorption decreased as pH increased. At low and high amino acid concentrations, the isotherms exhibited two apparent saturation coverages, which could be interpreted as 1:4 or 1:2 ratios of adsorbed molecule/surface Al sites. Tetradentate tetranuclear and bidentate binuclear species were the dominant conformations inferred independently from FTIR spectra. In these conformations, both carboxylate groups are involved in bonding to either four or to two Al surface atoms, through direct covalent bonds or via H-bonds. An outer sphere species, in which one carboxylate group interacts with a surface Al atom, could not be ruled out based on the FTIR spectra.

  2. Solid-State Synthesis, Characterization, and Biological Activity of the Bioinorganic Complex of Aspartic Acid and Arsenic Triiodide

    Directory of Open Access Journals (Sweden)

    Guo-Qing Zhong

    2013-01-01

    Full Text Available The bioinorganic complex of aspartic acid and arsenic triiodide was synthesized by a solid-state reaction at room temperature. The formula of the complex is AsI3[HOOCCH2CH(NH2COOH]2.5. The crystal structure of the complex belongs to monoclinic system with lattice parameters: a=1.0019 nm, b=1.5118 nm, c=2.1971 nm, and β=100.28°. The infrared spectra can demonstrate the complex formation between the arsenic ion and aspartic acid, and the complex may be a dimer with bridge structure. The result of primary biological test indicates that the complex possesses better biological activity for the HL-60 cells of the leukemia than arsenic triiodide.

  3. Nature of interactions of tryptophan with zinc oxide nanoparticles and L-aspartic acid: A spectroscopic approach

    Science.gov (United States)

    Mandal, Gopa; Bhattacharya, Sudeshna; Ganguly, Tapan

    2009-04-01

    The interaction between an essential amino acid L-tryptophan (TRP) with semiconductor zinc oxide (ZnO) nanoparticles and amino acid L-aspartic acid (ASP) is investigated by steady state and time resolved spectroscopic techniques. In both the cases static mode of fluorescence quenching occurs indicating the formation of ground-state complex. Binding constants and the number of binding sites were determined for both the complexes. The observed thermodynamic parameters suggest that the key interacting forces involved are van der Waals interaction and hydrogen bonding in case of TRP and ZnO nanoparticles whereas hydrophobic interaction is responsible in formations of TRP-ASP complex.

  4. 13C-NMR spectroscopic evaluation of the citric acid cycle flux in conditions of high aspartate transaminase activity in glucose-perfused rat hearts.

    Science.gov (United States)

    Tran-Dinh, S; Hoerter, J A; Mateo, P; Gyppaz, F; Herve, M

    1998-12-01

    A new mathematical model, based on the observation of 13C-NMR spectra of two principal metabolites (glutamate and aspartate), was constructed to determine the citric acid cycle flux in the case of high aspartate transaminase activity leading to the formation of large amounts of labeled aspartate and glutamate. In this model, the labeling of glutamate and aspartate carbons by chemical and isotopic exchange with the citric acid cycle are considered to be interdependent. With [U-13C]Glc or [1,2-(13)C]acetate as a substrate, all glutamate and aspartate carbons can be labeled. The isotopic transformations of 32 glutamate isotopomers into 16 aspartate isotopomers or vice versa were studied using matrix operations; the results were compiled in two matrices. We showed how the flux constants of the citric acid cycle and the 13C-enrichment of acetyl-CoA can be deduced from 13C-NMR spectra of glutamate and/or aspartate. The citric acid cycle flux in beating Wistar rat hearts, aerobically perfused with [U-13C]glucose in the absence of insulin, was investigated by 13C-NMR spectroscopy. Surprisingly, aspartate instead of glutamate was found to be the most abundantly-labeled metabolite, indicating that aspartate transaminase (which catalyses the reversible reaction: (glutamate + oxaloacetate 2-oxoglutarate + aspartate) is highly active in the absence of insulin. The amount of aspartate was about two times larger than glutamate. The quantities of glutamate (G0) or aspartate (A0) were approximately the same for all hearts and remained constant during perfusion: G0 = (0.74 +/- 0.03) micromol/g; A0 = (1.49 +/- 0.05) micromol/g. The flux constants, i.e., the fraction of glutamate and aspartate in exchange with the citric acid cycle, were about 1.45 min(-1) and 0.72 min(-1), respectively; the flux of this cycle is about (1.07 +/- 0.02) micromol min(-1) g(-1). Excellent agreement between the computed and experimental data was obtained, showing that: i) in the absence of insulin, only 41

  5. Conformation of a coarse-grained protein chain (an aspartic acid protease) model in effective solvent by a bond-fluctuating Monte Carlo simulation

    Science.gov (United States)

    Pandey, R. B.; Farmer, B. L.

    2008-03-01

    In a coarse-grained description of a protein chain, all of the 20 amino acid residues can be broadly divided into three groups: Hydrophobic (H) , polar (P) , and electrostatic (E) . A protein can be described by nodes tethered in a chain with a node representing an amino acid group. Aspartic acid protease consists of 99 residues in a well-defined sequence of H , P , and E nodes tethered together by fluctuating bonds. The protein chain is placed on a cubic lattice where empty lattice sites constitute an effective solvent medium. The amino groups (nodes) interact with the solvent (S) sites with appropriate attractive (PS) and repulsive (HS) interactions with the solvent and execute their stochastic movement with the Metropolis algorithm. Variations of the root mean square displacements of the center of mass and that of its center node of the protease chain and its gyration radius with the time steps are examined for different solvent strength. The structure of the protease swells on increasing the solvent interaction strength which tends to enhance the relaxation time to reach the diffusive behavior of the chain. Equilibrium radius of gyration increases linearly on increasing the solvent strength: A slow rate of increase in weak solvent regime is followed by a faster swelling in stronger solvent. Variation of the gyration radius with the time steps suggests that the protein chain moves via contraction and expansion in a somewhat quasiperiodic pattern particularly in strong solvent.

  6. Proton transport properties of poly(aspartic acid) with different average molecular weights

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yuki, E-mail: ynagao@kuchem.kyoto-u.ac.j [Department of Mechanical Systems and Design, Graduate School of Engineering, Tohoku University, 6-6-01 Aoba Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Imai, Yuzuru [Institute of Development, Aging and Cancer (IDAC), Tohoku University, 4-1 Seiryo-cho, Aoba-ku, Sendai 980-8575 (Japan); Matsui, Jun [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan); Ogawa, Tomoyuki [Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Miyashita, Tokuji [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2011-04-15

    Research highlights: Seven polymers with different average molecular weights were synthesized. The proton conductivity depended on the number-average degree of polymerization. The difference of the proton conductivities was more than one order of magnitude. The number-average molecular weight contributed to the stability of the polymer. - Abstract: We synthesized seven partially protonated poly(aspartic acids)/sodium polyaspartates (P-Asp) with different average molecular weights to study their proton transport properties. The number-average degree of polymerization (DP) for each P-Asp was 30 (P-Asp30), 115 (P-Asp115), 140 (P-Asp140), 160 (P-Asp160), 185 (P-Asp185), 205 (P-Asp205), and 250 (P-Asp250). The proton conductivity depended on the number-average DP. The maximum and minimum proton conductivities under a relative humidity of 70% and 298 K were 1.7 . 10{sup -3} S cm{sup -1} (P-Asp140) and 4.6 . 10{sup -4} S cm{sup -1} (P-Asp250), respectively. Differential thermogravimetric analysis (TG-DTA) was carried out for each P-Asp. The results were classified into two categories. One exhibited two endothermic peaks between t = (270 and 300) {sup o}C, the other exhibited only one peak. The P-Asp group with two endothermic peaks exhibited high proton conductivity. The high proton conductivity is related to the stability of the polymer. The number-average molecular weight also contributed to the stability of the polymer.

  7. Redox potentials of dopamine and its supramolecular complex with aspartic acid

    Science.gov (United States)

    Liu, Tao; Han, Ling-Li; Du, Chun-Mei; Yu, Zhang-Yu

    2014-07-01

    Dopamine (DA) can be oxidized to dopamine quinone (DAquinone) through a one-step, two-electron redox reaction. The electron transfer property of DA and its supramolecular complex with aspartic acid (Asp) has been investigated by the theoretical calculations. We calculated the standard redox potentials ( E o) of DA/DAquinone at the MP2/6-31G( d,p)//B3LYP/6-31G( d,p), MP2/6-31+G( d,p)//B3LYP/6-31+G( d,p), MP2/6-31G( d,p)//B3LYP/6-311G( d,p), and MP2/6-311+G( d,p)//B3LYP/6-311+G( d,p) levels. Comparing the experimental value, the redox potentials of DA/DAquinone obtained at MP2//B3LYP/6-311G( d,p) and MP2//B3LYP/6-311+G( d,p) levels can be considered as the upper and lower estimates. DA can form supramolecular complex (DA-Asp) with Asp through hydrogen bond (H-bond). Therefore, the values of 0.631 and 0.628 V obtained at MP2//B3LYP/6-311G( d,p) and MP2//B3LYP/6-311+G( d,p) levels for DA-Asp/DAquinone-Asp can be proposed as the upper and lower estimates of a probable (about 0.630 V) value of the corresponding redox potential. The calculated E o values of DA-Asp/DAquinone-Asp at the four theoretical levels are upper than those of DA/DAquinone, which indicates that the formation of H-bonds weaken the electron-donating ability of DA.

  8. N-Methyl D-Aspartic Acid (NMDA Receptors and Depression

    Directory of Open Access Journals (Sweden)

    Enver Yusuf Sivrioglu

    2009-06-01

    Full Text Available The monoaminergic hypothesis of depression has provided the basis for extensive research into the pathophysiology of mood disorders and has been of great significance for the development of effective antidepressants. Current antidepressant treatments not only increase serotonin and/or noradrenaline bioavailability but also originate adaptive changes increasing synaptic plasticity. Novel approaches to depression and to antidepressant therapy are now focused on intracellular targets that regulate neuroplasticity and cell survival. Accumulating evidence indicates that there is an anatomical substrate for such a devastating neuropsychiatric disease as major depression. Loss of synaptic plasticity and hippocampal atrophy appear to be prominent features of this highly prevalent disorder. A combination of genetic susceptibility and environmental factors make hippocampal neurons more vulnerable to stress. Abundant experimental evidence indicates that stress causes neuronal damage in brain regions, notably in hippocampal subfields. Stress-induced activation of glutamatergic transmission may induce neuronal cell death through excessive stimulation of N-methyl-D-aspartic acid (NMDA receptors. Recent studies mention that the increase of nitric oxide synthesis and inflammation in major depression may contribute to neurotoxicity through NMDA receptor. Both standard antidepressants and NMDA receptor antagonists are able to prevent stress-induced neuronal damage. NMDA antagonists are effective in widely used animal models of depression and some of them appear to be effective also in the few clinical trials performed to date. We are still far from understanding the complex cellular and molecular events involved in mood disorders. There appears to be an emerging role for glutamate neurotransmission in the search for the pathogenesis of major depression. Attenuation of NMDA receptor function mechanism appears to be a promising target in the search for a more

  9. Aspartic Acid 397 in Subunit B of the Na+-pumping NADH:Quinone Oxidoreductase from Vibrio cholerae Forms Part of a Sodium-binding Site, Is Involved in Cation Selectivity, and Affects Cation-binding Site Cooperativity

    Science.gov (United States)

    Shea, Michael E.; Juárez, Oscar; Cho, Jonathan; Barquera, Blanca

    2013-01-01

    The Na+-pumping NADH:quinone complex is found in Vibrio cholerae and other marine and pathogenic bacteria. NADH:ubiquinone oxidoreductase oxidizes NADH and reduces ubiquinone, using the free energy released by this reaction to pump sodium ions across the cell membrane. In a previous report, a conserved aspartic acid residue in the NqrB subunit at position 397, located in the cytosolic face of this protein, was proposed to be involved in the capture of sodium. Here, we studied the role of this residue through the characterization of mutant enzymes in which this aspartic acid was substituted by other residues that change charge and size, such as arginine, serine, lysine, glutamic acid, and cysteine. Our results indicate that NqrB-Asp-397 forms part of one of the at least two sodium-binding sites and that both size and charge at this position are critical for the function of the enzyme. Moreover, we demonstrate that this residue is involved in cation selectivity, has a critical role in the communication between sodium-binding sites, by promoting cooperativity, and controls the electron transfer step involved in sodium uptake (2Fe-2S → FMNC). PMID:24030824

  10. Potentiometric and spectral studies of complex formation of La(III), Pr(III) and Lu(III) with aspartic acid and asparagine

    Energy Technology Data Exchange (ETDEWEB)

    Wojciechowska, A.; Lomozik, L.; Zielinski, S.

    1987-12-01

    The composition and stability of La/sup 3 +/, Pr/sup 3 +/ and Lu/sup 3 +/ complexes with aspartic acid and asparagine were analysed. The formation of complexes of the type ML and MHL was determined for La/sup 3 +/ and Pr/sup 3 +/ with aspartic acid, and of the type MHL for Lu/sup 3 +/ with aspartic acid. For La/sup 3 +/, Pr/sup 3 +/ and Lu/sup 3 +/ with asparagine the formation of ML(OH) complexes was observed. By means of /sup 1/H NMR and /sup 13/C NMR studies the participation in the coordination of both -COOH groups was determined for aspartic acid, whereas for asparagine the participation of the -COOH group was determined in complexes with La/sup 3 +/, Pr/sup 3 +/, and of the -COOH and the -NH/sub 2/ groups in the complex with Lu/sup 3 +/.

  11. Comments on the paper: 'Optical reflectance, optical refractive index and optical conductivity measurements of nonlinear optics for L-aspartic acid nickel chloride single crystal'

    Science.gov (United States)

    Srinivasan, Bikshandarkoil R.; Naik, Suvidha G.; Dhavskar, Kiran T.

    2016-02-01

    We argue that the 'L-aspartic acid nickel chloride' crystal reported by the authors of the title paper (Optics Communications, 291 (2013) 304-308) is actually the well-known diaqua(L-aspartato)nickel(II) hydrate crystal.

  12. A novel aspartic acid protease gene from pineapple fruit (Ananas comosus): cloning, characterization and relation to postharvest chilling stress resistance.

    Science.gov (United States)

    Raimbault, Astrid-Kim; Zuily-Fodil, Yasmine; Soler, Alain; Cruz de Carvalho, Maria H

    2013-11-15

    A full-length cDNA encoding a putative aspartic acid protease (AcAP1) was isolated for the first time from the flesh of pineapple (Ananas comosus) fruit. The deduced sequence of AcAP1 showed all the common features of a typical plant aspartic protease phytepsin precursor. Analysis of AcAP1 gene expression under postharvest chilling treatment in two pineapple varieties differing in their resistance to blackheart development revealed opposite trends. The resistant variety showed an up-regulation of AcAP1 precursor gene expression whereas the susceptible showed a down-regulation in response to postharvest chilling treatment. The same trend was observed regarding specific AP enzyme activity in both varieties. Taken together our results support the involvement of AcAP1 in postharvest chilling stress resistance in pineapple fruits.

  13. Relationship between structure, conformational flexibility, and biological activity of agonists and antagonists at the N-methyl-D-aspartic acid subtype of excitatory amino acid receptors

    DEFF Research Database (Denmark)

    Madsen, U; Brehm, L; Schaumburg, Kjeld;

    1990-01-01

    The relationship between conformational flexibility and agonist or antagonist actions at the N-Methyl-D-aspartic acid (NMDA) subtype of central L-glutamic acid (GLU) receptors of a series of racemic piperidinedicarboxylic acids (PDAs) was studied. The conformational analyses were based on 1H NMR...... receptors. Each of the three cyclic acidic amino acids showing NMDA agonist activities was found to exist as an equilibrium mixture of two conformers in aqueous solution. In contrast, the NMDA antagonists cis-2,3-PDA and cis-2,4-PDA as well as the inactive compounds trans-2,5-PDA and cis-2,6-PDA were shown...

  14. A new and concise strategy to the enantioselective synthesis of (S)-2-amino-4-oxo-4-(pyridine-2-yl) butanoic acid from aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Evanoel Crizanto de; Souza, Carolina C. de; Maior, Marta C.L.S.; Costa, Paulo R.R., E-mail: prrcosta@ism.com.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Centro de Ciencias da Saude. Nucleo de Pesquisas de Produtos Naturais; Lima, Paulo G. de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica; Dias, Ayres G. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Inst. de Quimica

    2010-07-01

    The alpha-amino acid (S)-5 was synthesized using in the key step a chemoselective nucleophilic substitution between a diester derived from L-aspartic acid and 2-lithium pyridine. The overall yield (13%, 5 steps) was similar to those previously described by our group for the R isomer (the first exogen full agonist of the NMDA receptors) from D-mannitol (12%, 10 steps) and by Lovey and Copper for the racemic synthesis (17%, 5 steps). (author)

  15. Structural and Biochemical Characterization of a Copper-Binding Mutant of the Organomercurial Lyase MerB: Insight into the Key Role of the Active Site Aspartic Acid in Hg-Carbon Bond Cleavage and Metal Binding Specificity.

    Science.gov (United States)

    Wahba, Haytham M; Lecoq, Lauriane; Stevenson, Michael; Mansour, Ahmed; Cappadocia, Laurent; Lafrance-Vanasse, Julien; Wilkinson, Kevin J; Sygusch, Jurgen; Wilcox, Dean E; Omichinski, James G

    2016-02-23

    In bacterial resistance to mercury, the organomercurial lyase (MerB) plays a key role in the detoxification pathway through its ability to cleave Hg-carbon bonds. Two cysteines (C96 and C159; Escherichia coli MerB numbering) and an aspartic acid (D99) have been identified as the key catalytic residues, and these three residues are conserved in all but four known MerB variants, where the aspartic acid is replaced with a serine. To understand the role of the active site serine, we characterized the structure and metal binding properties of an E. coli MerB mutant with a serine substituted for D99 (MerB D99S) as well as one of the native MerB variants containing a serine residue in the active site (Bacillus megaterium MerB2). Surprisingly, the MerB D99S protein copurified with a bound metal that was determined to be Cu(II) from UV-vis absorption, inductively coupled plasma mass spectrometry, nuclear magnetic resonance, and electron paramagnetic resonance studies. X-ray structural studies revealed that the Cu(II) is bound to the active site cysteine residues of MerB D99S, but that it is displaced following the addition of either an organomercurial substrate or an ionic mercury product. In contrast, the B. megaterium MerB2 protein does not copurify with copper, but the structure of the B. megaterium MerB2-Hg complex is highly similar to the structure of the MerB D99S-Hg complexes. These results demonstrate that the active site aspartic acid is crucial for both the enzymatic activity and metal binding specificity of MerB proteins and suggest a possible functional relationship between MerB and its only known structural homologue, the copper-binding protein NosL.

  16. Mutation of aspartic acid-351, lysine-352, and lysine-515 alters the Ca2+ transport activity of the Ca2+-ATPase expressed in COS-1 cells.

    Science.gov (United States)

    Maruyama, K; MacLennan, D H

    1988-01-01

    Full-length cDNAs encoding neonatal and adult isoforms of the Ca2+-ATPase of rabbit fast-twitch skeletal muscle sarcoplasmic reticulum were expressed transiently in COS-1 cells. The microsomal fraction isolated from transfected COS-1 cells contained immunoreactive Ca2+-ATPase and catalyzed Ca2+ transport at rates at least 15-fold above controls. No differences were observed in either the rates or Ca2+ dependency of Ca2+ transport catalyzed by the two isoforms. Aspartic acid-351, the site of formation of the catalytic acyl phosphate in the enzyme, was mutated to asparagine, glutamic acid, serine, threonine, histidine, or alanine. In every case, Ca2+ transport activity and Ca2+-dependent phosphorylation were eliminated. Ca2+ transport was also eliminated by mutation of lysine-352 to arginine, glutamine, or glutamic acid or by mutation of Asp351-Lys352 to Lys351-Asp352. Mutation of lysine-515, the site of fluorescein isothiocyanate modification in the enzyme, resulted in diminished Ca2+ transport activity as follows: arginine, 60%; glutamine, 25%; glutamic acid, 5%. These results demonstrate the absolute requirement of acylphosphate formation for the Ca2+ transport function and define a residue important for ATP binding. They also demonstrate the feasibility of a thorough analysis of active sites in the Ca2+-ATPase by expression and site-specific mutagenesis. Images PMID:2966962

  17. The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats

    Directory of Open Access Journals (Sweden)

    Ronsini Salvatore

    2009-10-01

    Full Text Available Abstract Background D-aspartic acid is an amino acid present in neuroendocrine tissues of invertebrates and vertebrates, including rats and humans. Here we investigated the effect of this amino acid on the release of LH and testosterone in the serum of humans and rats. Furthermore, we investigated the role of D-aspartate in the synthesis of LH and testosterone in the pituitary and testes of rats, and the molecular mechanisms by which this amino acid triggers its action. Methods For humans: A group of 23 men were given a daily dose of D-aspartate (DADAVIT® for 12 days, whereas another group of 20 men were given a placebo. For rats: A group of 10 rats drank a solution of either 20 mM D-aspartate or a placebo for 12 days. Then LH and testosterone accumulation was determined in the serum and D-aspartate accumulation in tissues. The effects of D-aspartate on the synthesis of LH and testosterone were gauged on isolated rat pituitary and Leydig cells. Tissues were incubated with D-aspartate, and then the concentration (synthesis of LH and cGMP in the pituitary and of testosterone and cAMP in the Leydig cells was determined. Results In humans and rats, sodium D-aspartate induces an enhancement of LH and testosterone release. In the rat pituitary, sodium D-aspartate increases the release and synthesis of LH through the involvement of cGMP as a second messenger, whereas in rat testis Leydig cells, it increases the synthesis and release of testosterone and cAMP is implicated as second messenger. In the pituitary and in testes D-Asp is synthesized by a D-aspartate racemase which convert L-Asp into D-Asp. The pituitary and testes possesses a high capacity to trapping circulating D-Asp from hexogen or endogen sources. Conclusion D-aspartic acid is a physiological amino acid occurring principally in the pituitary gland and testes and has a role in the regulation of the release and synthesis of LH and testosterone in humans and rats.

  18. LC-MS analysis of the formed peptides from N-( O, O-diiso-propyl) phosphoryl aspartic acid

    Institute of Scientific and Technical Information of China (English)

    胡建军; 巨勇; 赵玉芬

    2000-01-01

    IC-ESI-MS method was used to analyze the formed di- and ri- peptide in the reaction system of N-(O, O-diisopropyl) phosphoryl aspartic acid and adenosine. Cluster ions of the peptides were given in the ESI-MS. The structures of these small peptides were confirmed by LC-MS-MS analysis. Compared wih the traditional HPLC-UV detection, this method showed good sensitivity and selectivity for peptide in the presence of compounds with strong UV ahsorption, such as nucleoside and nucleotide.

  19. 聚天冬氨酸的合成研究%Study on the synthesis of poly-aspartic acid

    Institute of Scientific and Technical Information of China (English)

    陈舜; 周志明; 于超俊

    2011-01-01

    以马来酸为原料,通过三步反应合成了聚天冬氨酸.聚天冬氨酸合成的最佳工艺条件为:马来酸与尿素的摩尔比为1/0.95,反应温度为95.0℃,反应时间为3.75 h,马来酸铵盐与磷酸的质量比为1/0.55,氢氧化钠的用量为7.5 mL,水解温度为45℃,水解时间为55 min.此时,聚天冬氨酸的产率为83.0%.%Using maleic as raw material, poly-aspartic acid was synthesized by three steps.The optimum conditions of synthesis of poly-aspartic acid were as follows: molar ratio of maleic to urea 1/0.95, reaction temperature 95.0 ℃.,reaction time 3.75 h,mass ratio of maleic ammonium to phosphoric acid 1/0.55, amount of sodium hydroxide 7.5 mL, hydrolysis temperature 45 ℃, hydrolysis time 55 min.Under these conditions,the yield of PASP was 83.0%.

  20. Allosteric Inhibition of Phosphoenolpyruvate Carboxylases is Determined by a Single Amino Acid Residue in Cyanobacteria

    Science.gov (United States)

    Takeya, Masahiro; Hirai, Masami Yokota; Osanai, Takashi

    2017-01-01

    Phosphoenolpyruvate carboxylase (PEPC) is an important enzyme for CO2 fixation and primary metabolism in photosynthetic organisms including cyanobacteria. The kinetics and allosteric regulation of PEPCs have been studied in many organisms, but the biochemical properties of PEPC in the unicellular, non-nitrogen-fixing cyanobacterium Synechocystis sp. PCC 6803 have not been clarified. In this study, biochemical analysis revealed that the optimum pH and temperature of Synechocystis 6803 PEPC proteins were 7.3 and 30 °C, respectively. Synechocystis 6803 PEPC was found to be tolerant to allosteric inhibition by several metabolic effectors such as malate, aspartate, and fumarate compared with other cyanobacterial PEPCs. Comparative sequence and biochemical analysis showed that substitution of the glutamate residue at position 954 with lysine altered the enzyme so that it was inhibited by malate, aspartate, and fumarate. PEPC of the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 was purified, and its activity was inhibited in the presence of malate. Substitution of the lysine at position 946 (equivalent to position 954 in Synechocystis 6803) with glutamate made Anabaena 7120 PEPC tolerant to malate. These results demonstrate that the allosteric regulation of PEPC in cyanobacteria is determined by a single amino acid residue, a characteristic that is conserved in different orders. PMID:28117365

  1. Evidence for increased cellular uptake of glutamate and aspartate in the rat hippocampus during kainic acid seizures. A microdialysis study using the "indicator diffusion' method

    DEFF Research Database (Denmark)

    Bruhn, T; Christensen, Thomas; Diemer, Nils Henrik

    1997-01-01

    Using a newly developed technique, based on microdialysis, which allows cellular uptake of glutamate and aspartate to be studied in awake animals, we investigated uptake of glutamate and aspartate in the hippocampal formation of rats during limbic seizures induced by systemical administration of ....... The results indicate that during KA-induced seizures, uptake of glutamate and aspartate is increased, possibly aimed at maintaining the extracellular homeostasis of these two excitatory amino acids.......Using a newly developed technique, based on microdialysis, which allows cellular uptake of glutamate and aspartate to be studied in awake animals, we investigated uptake of glutamate and aspartate in the hippocampal formation of rats during limbic seizures induced by systemical administration...... of kainic acid (KA). With [14C]mannitol as an extracellular reference substance, the cellular extraction of the test substance [3H]D-aspartate was measured at different stages of seizure-activity. The results were compared to those obtained in a sham operated control group. During severe generalized clonic...

  2. Microwave-assisted synthesis, crystal structure and toxicity of L-aspartic acid zinc spiral linear supramolecular polymer

    Institute of Scientific and Technical Information of China (English)

    ZHANG Youming; LIN Qi; WEI Taibao

    2004-01-01

    L-aspartic acid zinc was synthesized by a rapid and convenient method in high yield under microwave conditions, and its single crystal structure was analyzed by X-ray diffraction.forming a spiral linear polymer via coordination bonds. The spiral linear polymers are assembled as a three-dimensional supramolecule by intermolecular hydrogen bonds. The crystal belongs to the orthorhombic crystal system, P2(1)2(1)2(1) space group, a=0.7830(3) nm,b=0.9369(4) nm,c=11.599(5) nm, α =β=γ=90.00°, V=0.8509(6) nm3, Z=4, Dc=1.955 g/cm3, F(000)=512, μ =2.289.The toxicity of the title compound is lower than that of glutamic acid zinc and zinc sulfate.

  3. 3T3 fibroblasts transfected with a cDNA for mitochondrial aspartate aminotransferase express plasma membrane fatty acid-binding protein and saturable fatty acid uptake.

    OpenAIRE

    1995-01-01

    To explore the relationship between mitochondrial aspartate aminotransferase (mAspAT; EC 2.6.1.1) and plasma membrane fatty acid-binding protein (FABPpm) and their role in cellular fatty acid uptake, 3T3 fibroblasts were cotransfected with plasmid pMAAT2, containing a full-length mAspAT cDNA downstream of a Zn(2+)-inducible metallothionein promoter, and pFR400, which conveys methotrexate resistance. Transfectants were selected in methotrexate, cloned, and exposed to increasing methotrexate co...

  4. L-天冬氨酸生产、应用与市场前景%Production, application and market prospect of L-aspartic acid

    Institute of Scientific and Technical Information of China (English)

    胡育骄; 刘勇; 程池

    2013-01-01

    L-aspartic acid is widely used in food,chemical,medicine and other fields.It has good development value and broad application prospects.We reviewed the production methods and application of L-aspartic acid,and outlined the development prospects of L-aspartic acid in China.%L-天冬氨酸广泛应用于食品、化工、医药等领域,具有巨大的开发价值和广阔的应用前景.文中介绍了L-天冬氨酸国内外生产方法和产品应用领域,并对L-天冬氨酸在我国的开发前景进行了概述.

  5. Distribution of messenger RNAs encoding the enzymes glutaminase, aspartate aminotransferase and glutamic acid decarboxylase in rat brain.

    Science.gov (United States)

    Najlerahim, A; Harrison, P J; Barton, A J; Heffernan, J; Pearson, R C

    1990-05-01

    In situ hybridization histochemistry (ISHH) using synthetic oligonucleotide probes has been used to identify cells containing the mRNAs coding for glutaminase (GluT), aspartate aminotransferase (AspT) and glutamic acid decarboxylase (GAD). The distribution of GAD mRNA confirms previous descriptions and matches the distribution of GAD detected using specific antibodies. AspT mRNA is widely distributed in the brain, but is present at high levels in GABAergic neuronal populations, some that may be glutamatergic, and in a subset of neurons which do not contain significant levels of either GAD or GluT mRNA. Particularly prominent are the neurons of the magnocellular division of the red nucleus, the large cells in the deep cerebellar nuclei and the vestibular nuclei and neurons of the lateral superior olivary nucleus. GluT mRNA does not appear to be present at high levels in all GAD-containing neurons, but is seen prominently in many neuronal populations that may use glutamate as a neurotransmitter, such as neocortical and hippocampal pyramidal cells, the granule cells of the cerebellum and neurons of the dentate gyrus of the hippocampus. The heaviest labelling of GluT mRNA is seen in the lateral reticular nucleus of the medulla. ISHH using probes directed against the mRNAs encoding these enzymes may be an important technique for identifying glutamate and aspartate using neuronal populations and for examining their regulation in a variety of experimental and pathological circumstances.

  6. Development of novel radiogallium-labeled bone imaging agents using oligo-aspartic acid peptides as carriers.

    Directory of Open Access Journals (Sweden)

    Kazuma Ogawa

    Full Text Available (68Ga (T 1/2 = 68 min, a generator-produced nuclide has great potential as a radionuclide for clinical positron emission tomography (PET. Because poly-glutamic and poly-aspartic acids have high affinity for hydroxyapatite, to develop new bone targeting (68Ga-labeled bone imaging agents for PET, we used 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA as a chelating site and conjugated aspartic acid peptides of varying lengths. Subsequently, we compared Ga complexes, Ga-DOTA-(Aspn (n = 2, 5, 8, 11, or 14 with easy-to-handle (67Ga, with the previously described (67Ga-DOTA complex conjugated bisphosphonate, (67Ga-DOTA-Bn-SCN-HBP. After synthesizing DOTA-(Aspn by a Fmoc-based solid-phase method, complexes were formed with (67Ga, resulting in (67Ga-DOTA-(Aspn with a radiochemical purity of over 95% after HPLC purification. In hydroxyapatite binding assays, the binding rate of (67Ga-DOTA-(Aspn increased with the increase in the length of the conjugated aspartate peptide. Moreover, in biodistribution experiments, (67Ga-DOTA-(Asp8, (67Ga-DOTA-(Asp11, and (67Ga-DOTA-(Asp14 showed high accumulation in bone (10.5 ± 1.5, 15.1 ± 2.6, and 12.8 ± 1.7% ID/g, respectively but were barely observed in other tissues at 60 min after injection. Although bone accumulation of (67Ga-DOTA-(Aspn was lower than that of (67Ga-DOTA-Bn-SCN-HBP, blood clearance of (67Ga-DOTA-(Aspn was more rapid. Accordingly, the bone/blood ratios of (67Ga-DOTA-(Asp11 and (67Ga-DOTA-(Asp14 were comparable with those of (67Ga-DOTA-Bn-SCN-HBP. In conclusion, these data provide useful insights into the drug design of (68Ga-PET tracers for the diagnosis of bone disorders, such as bone metastases.

  7. Subcellular distribution of N-methyl-D-aspartic acid receptor subunit 1 in neural stem cells within subventricular zone of adult rats

    Institute of Scientific and Technical Information of China (English)

    Zhining Li; Wenlong Lü; Hongyan Dong; Hongbin Fan; Ruiguo Dong; Tiejun Xu

    2011-01-01

    The subcellular localization of N-methyl-D-aspartic acid receptor subunit 1 in neural stem cells of the subventricular zone of adult rats was detected using electron microscopy, following immunohistochemistry and immunogold-silver double staining. Results confirmed the presence of neural stem cells in the subventricular zone, which is a key neurogenic region in the central nervous system of adult mammals. The expression of N-methyl-D-aspartic acid receptor subunit 1 was higher than that of nestin and mainly distributed in the cell membrane, cytoplasm, rough endoplasmic reticulum and Golgi complex of neural stem cells.

  8. Fatty Acid Structure and Degradation Analysis in Fingerprint Residues

    Science.gov (United States)

    Pleik, Stefanie; Spengler, Bernhard; Schäfer, Thomas; Urbach, Dieter; Luhn, Steven; Kirsch, Dieter

    2016-09-01

    GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl- N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints.

  9. Heat-initiated prebiotic formation of peptides from glycine/aspartic acid and glycine/valine in aqueous environment and clay suspension

    Science.gov (United States)

    Pant, Chandra Kala; Lata, Hem; Pathak, Hari Datt; Mehata, Mohan Singh

    2009-04-01

    The effect of heat on the reaction system of glycine/aspartic acid and glycine/valine in the aqueous environment as well as in montmorillonite clay suspension with or without divalent cations (Ca2+, Mg2+ and Ni2+) has been investigated at 85°C±5°C for varying periods under prebiotic drying and wetting conditions. The resulting products were analysed and characterized by chromatographic and spectroscopic methods. Peptide formation appears to depend on the duration of heat effect, nature of reactant amino acids and, to some extent, on montmorillonite clay incorporated with divalent cations. In the glycine/aspartic acid system, oligomerization of glycine was limited up to trimer level (Gly)3 along with the formation of glycyl-aspartic acid, while linear and cyclic peptides of aspartic acid were not formed, whereas the glycine/valine system preferentially elongated homo-oligopeptide of glycine up to pentamer level (Gly)5 along with formation of hetero-peptides (Gly-Val and Val-Gly). These studies are relevant in the context of the prebiotic origin of proteins and the role of clay and metal ions in condensation and oligomerization of amino acids. The length of the bio-oligomer chain depends upon the reaction conditions. However, condensation into even a small length seems significant, as the same process would have taken millions of years in the primitive era of the Earth, leading to the first proteins.

  10. Stability of Aspartic Acid at 77°K under Gamma Radiation in a Comet Cores Simulation: Implications for Chemical Evolution Studies

    Directory of Open Access Journals (Sweden)

    A. L. Meléndez-López

    2016-08-01

    Full Text Available The synthesis of organic matter in a simulated primitive environment (terrestrial or extraterrestrial has been widely studied. The stability of organic matter of biological significance, exposed to energy fields in primitive conditions, is equally important in the context of chemical evolution. We present a detailed analysis of the stability of prebiotic organic molecules under the effect of ionizing radiation at a low temperature, simulating a comet core. The laboratory simulation consists of icy phases of prototype organic matter and a mineral in a physical mixture. This chemical system was irradiated with gamma radiation at 77°K. The icy phases are methanol, formic acid, and aspartic acid in aqueous solution, in the presence of sodium montmorillonite as silicates surface.Our results show the stability of aspartic acid in this comet core simulation. We have been identified some radiolytic products of this mixture: ethylene glycol, glycolaldehyde, formamide, alanine, glycine and succinic acid. The products were identified by Gas Chromatography (GC and High Performance Liquid Chromatography-Electrospray IonizationMass Spectrometry (HPLC-ESI-MS. The protection role of the clay in the radiolysis of aspartic acid was observed in this mixture. This result may be due to an energy transfer from the clay. At pH=4, aspartic acid is adsorbed onto the clay at the interlayer channel as is shown in the X-ray diffractograms (XRD.

  11. In vitro effects of zinc, D-aspartic acid, and coenzyme-Q10 on sperm function.

    Science.gov (United States)

    Giacone, Filippo; Condorelli, Rosita A; Mongioì, Laura M; Bullara, Valentina; La Vignera, Sandro; Calogero, Aldo E

    2016-07-15

    Reactive oxygen species favor reproductive processes at low concentrations, but damage spermatozoa and decrease their fertilizing capacity at high concentrations. During infection and/or inflammation of the accessory sex glands reactive oxygen species overproduction may occur which, in turn, may negatively impact on sperm motility, sperm DNA fragmentation, and lipid peroxidation. A number of nutraceutical formulations containing antioxidant molecules have been developed to counteract the deleterious effects of the oxidative stress. A recent formulation containing zinc, D-aspartic acid, and coenzyme-Q10 is present in the pharmaceutical market. Based on these premises, the aim of the present study was to evaluate the effects of this combination on spermatozoa in vitro. The study was conducted on 24 men (32.2 ± 5.5 years): 12 normozoospermic men and 12 asthenozoospermic patients. Spermatozoa from each sample were divided into two control aliquots (aliquot A and B) and an aliquot incubated with zinc, D-aspartic acid, and coenzyme-Q10 (aliquot C). After 3 h of incubation, the following parameters were evaluated: progressive motility, number of spermatozoa with progressive motility recovered after swim-up, lipid peroxidation, and DNA fragmentation. Incubation with zinc, D-aspartic acid, and coenzyme-Q10 maintained sperm motility in normozoospermic men (37.7 ± 1.2 % vs. 35.8 ± 2.3 % at time zero) and improved it significantly in asthenozoospermic patients (26.5 ± 1.9 % vs. 18.8 ± 2.0 % at time zero) (p < 0.01). This resulted in a significantly higher (p < 0.01) number of spermatozoa with progressive motility recovered after swim-up in both normozospermic men (4.1 ± 0.9 vs. 3.3 ± 1.0 millions) and asthenozooseprmic patients (3.2 ± 0.8 vs. 1.6 ± 0.5 millions). Finally, a statistically significant lower sperm lipid peroxidation was found after incubation with zinc, D-aspartic acid, and coenzyme-Q10 (p < 0

  12. Effect of heavy metals and phenol on bacterial decolourisation and COD reduction of sucrose-aspartic acid Maillard product

    Institute of Scientific and Technical Information of China (English)

    Sangeeta Yadav; Ram Chandra

    2013-01-01

    Melanodins are amino-carbonyl complex,predominantly present in sugarcane molasses based distillery wastewater as major source of colourant.The microbial decolourisation of melanoidin is a challenge due to its binding property with other co-pollutants of distillery waste.Results revealed that the presence of Zn2+ (2.00-20.00 mg/L) in melanoidin solution (1200 mg/L) stimulated the bacterial growth and sucrose-aspartic acid Maillard product (SAA) decolourisation as compared to control,while Fe3+ and Mn2+ at the same concentration inhibited the process.However,the presence of phenol (100 mg/L) along with Zn2+,Fe3+ and Mn2+ suppressed the bacterial growth,SAA decolourisation and MnP activity.The shrinkage and reduced number of bacterial cell count at higher concentration of heavy metals in presence of phenol was also observed under scanning electron microscope.

  13. Synthesis, characterization and application of a novel chemical sand-fixing agent-poly(aspartic acid) and its composites

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China); Wang Fang [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China); Fang Li [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China); Tan Tianwei [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China)]. E-mail: twtan@mail.buct.edu.cn

    2007-09-15

    A novel sand-fixing agent-poly(aspartic acid) and its composites were synthesized to improve sand particles compressive strength and anti-wind erosion properties. The relationship between the concentration of sand-fixing agent and the sand-fixing properties was studied by three kinds of aging tests. Some composites were choose to improve the sand-fixing property and the composition of 40% xanthan gum and 60% ethyl cellulose were chosen to compare sand-fixing property with lignosulfonate. The results showed that the sand-fixing and water-retaining properties of xanthan gum and ethyl cellulose composites were better than that of lignosulfonate. The biodegradability experiment showed that the PASP and its composites were environment-friendly products and the field test showed that the PASP composites could improve wind erosion disturbance. - A novel biodegradability polymer significantly improved sand particles' compressive strength and anti-wind erosion properties.

  14. Preparation of γ-aminopropyltriethoxysilane cross-linked poly(aspartic acid) superabsorbent hydrogels without organic solvent.

    Science.gov (United States)

    Meng, Hongyu; Zhang, Xin; Sun, Shenyu; Tan, Tianwei; Cao, Hui

    2016-01-01

    Poly(aspartic acid) (PASP) hydrogel is a type of biodegradable and biocompatible polymer with high water absorbing ability. Traditionally, the production of PASP hydrogel is expensive, complex, environmentally unfriendly, and consumes a large amount of organic solvents, e.g. dimethylformamide or dimethylsulfoxide. This study introduces a one-step synthesis of PASP resin, in which the organic phase was replaced by distilled water and γ-aminopropyltriethoxysilane was used as the cross-linker. Absorbent ability and characteristics were determined by swelling ratio, FTIR, (13)C SSNMR, and SEM. In vitro cytotoxicity evaluation and animal skin irritation tests showed the hydrogel has body-friendly properties. Preparing PASP hydrogel in aqueous solution is promising and finds its use in many applications.

  15. Biocompatibility of helicoidal multilamellar arginine-glycine-aspartic acid-functionalized silk biomaterials in a rabbit corneal model.

    Science.gov (United States)

    Wang, Liqiang; Ma, Ruijue; Du, Gaiping; Guo, Huiling; Huang, Yifei

    2015-01-01

    Silk proteins represent a unique choice in the selection of biomaterials that can be used for corneal tissue engineering and regenerative medical applications. We implanted helicoidal multilamellar arginine-glycine-aspartic acid-functionalized silk biomaterials into the corneal stroma of rabbits, and evaluated its biocompatibility. The corneal tissue was examined after routine hematoxylin-eosin staining, immunofluorescence for collagen I and III, and fibronectin, and scanning electron microscopy. The silk films maintained their integrity and transparency over the 180-day experimental period without causing immunogenic and neovascular responses or degradation of the rabbit corneal stroma. Collagen I increased, whereas Collagen III and fibronectin initially increased and then gradually decreased. The extracellular matrix deposited on the surface of the silk films, tightly adhered to the biomaterial. We have shown this kind of silk film graft has suitable biocompatibility with the corneal stroma and is an initial step for clinical trials to evaluate this material as a transplant biomaterial for keratoplasty tissue constructs.

  16. Aspartic acid racemization rate in narwhal (Monodon monoceros eye lens nuclei estimated by counting of growth layers in tusks

    Directory of Open Access Journals (Sweden)

    Eva Garde

    2012-11-01

    Full Text Available Ages of marine mammals have traditionally been estimated by counting dentinal growth layers in teeth. However, this method is difficult to use on narwhals (Monodon monoceros because of their special tooth structures. Alternative methods are therefore needed. The aspartic acid racemization (AAR technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid d/l ratios in eye lens nuclei against growth layer groups in tusks (n=9. Two racemization rates were estimated: one by linear regression (r2=0.98 based on the assumption that age was known without error, and one based on a bootstrap study, taking into account the uncertainty in the age estimation (r2 between 0.88 and 0.98. The two estimated 2kAsp values were identical up to two significant figures. The 2k Asp value from the bootstrap study was found to be 0.00229±0.000089 SE, which corresponds to a racemization rate of 0.00114−yr±0.000044 SE. The intercept of 0.0580±0.00185 SE corresponds to twice the (d/l0 value, which is then 0.0290±0.00093 SE. We propose that this species-specific racemization rate and (d/l0 value be used in future AAR age estimation studies of narwhals, but also recommend the collection of tusks and eyes of narwhals for further improving the (d/l0 and 2kAsp estimates obtained in this study.

  17. Injectable dopamine-modified poly(α,β-aspartic acid) nanocomposite hydrogel as bioadhesive drug delivery system.

    Science.gov (United States)

    Gong, Chu; Lu, Caicai; Li, Bingqiang; Shan, Meng; Wu, Guolin

    2017-04-01

    Hydrogel systems based on cross-linked polymeric materials with adhesive properties in wet environments have been considered as promising candidates for tissue adhesives. The 3,4-dihydroxyphenylalanine (DOPA) is believed to be responsible for the water-resistant adhesive characteristics of mussel adhesive proteins. Under the inspiration of DOPA containing adhesive proteins, a dopamine-modified poly(α,β-aspartic acid) derivative (PDAEA) was successfully synthesized by successive ring-opening reactions of polysuccinimide (PSI) with dopamine and ethanolamine, and an injectable bioadhesive hydrogel was prepared via simply mixing PDAEA and FeCl3 solutions. The formation mechanism of the hydrogel was investigated by ultraviolet-visible (UV-vis) spectroscopic, Fourier transformation infrared (FT-IR) spectroscopic, visual colorimetric measurements and EDTA immersion methods. The study demonstrated that the PDAEA-Fe(3+) hydrogel is a dual cross-linking system composed of covalent and coordination crosslinks. The PDAEA-Fe(3+) hydrogel is suitable to serve as a bioadhesive agent according to the rheological behaviors and the observed significant shear adhesive strength. The slow and sustained release of the model drug curcumin from the hydrogel in vitro demonstrated the hydrogel could also be potentially used for drug delivery. Moreover, the cytotoxicity tests in vitro suggested the prepared polymer and hydrogel possessed excellent cytocompatibility. All the results indicated that the dopamine modified poly(α,β-aspartic acid) derivative based hydrogel was a promising candidate for bioadhesive drug delivery system. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1000-1008, 2017.

  18. IgE binding to peanut allergens is inhibited by combined D-aspartic and D-glutamic acids.

    Science.gov (United States)

    Chung, Si-Yin; Reed, Shawndrika

    2015-01-01

    The objective of this study was to determine if D-amino acids (D-aas) bind and inhibit immunoglobulin E (IgE) binding to peanut allergens. D-aas such as D-Asp (aspartic acid), D-Glu (glutamic acid), combined D-[Asp/Glu] and others were each prepared in a cocktail of 9 other D-aas, along with L-amino acids (L-aas) and controls. Each sample was mixed with a pooled plasma from peanut-allergic donors, and tested by ELISA (enzyme-linked immunosorbent assay) and Western blots for IgE binding to peanut allergens. Results showed that D-[Asp/Glu] (4 mg/ml) inhibited IgE binding (75%) while D-Glu, D-Asp and other D-aas had no inhibitory effect. A higher inhibition was seen with D-[Asp/Glu] than with L-[Asp/Glu]. We concluded that IgE was specific for D-[Asp/Glu], not D-Asp or D-Glu, and that D-[Asp/Glu] was more reactive than was L-[Asp/Glu] in IgE inhibition. The finding indicates that D-[Asp/Glu] may have the potential for removing IgE or reducing IgE binding to peanut allergens in vitro.

  19. Co-expression of bacterial aspartate kinase and adenylylsulfate reductase genes substantially increases sulfur amino acid levels in transgenic alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Tong, Zongyong; Xie, Can; Ma, Lei; Liu, Liping; Jin, Yongsheng; Dong, Jiangli; Wang, Tao

    2014-01-01

    Alfalfa (Medicago sativa L.) is one of the most important forage crops used to feed livestock, such as cattle and sheep, and the sulfur amino acid (SAA) content of alfalfa is used as an index of its nutritional value. Aspartate kinase (AK) catalyzes the phosphorylation of aspartate to Asp-phosphate, the first step in the aspartate family biosynthesis pathway, and adenylylsulfate reductase (APR) catalyzes the conversion of activated sulfate to sulfite, providing reduced sulfur for the synthesis of cysteine, methionine, and other essential metabolites and secondary compounds. To reduce the feedback inhibition of other metabolites, we cloned bacterial AK and APR genes, modified AK, and introduced them into alfalfa. Compared to the wild-type alfalfa, the content of cysteine increased by 30% and that of methionine increased substantially by 60%. In addition, a substantial increase in the abundance of essential amino acids (EAAs), such as aspartate and lysine, was found. The results also indicated a close connection between amino acid metabolism and the tricarboxylic acid (TCA) cycle. The total amino acid content and the forage biomass tested showed no significant changes in the transgenic plants. This approach provides a new method for increasing SAAs and allows for the development of new genetically modified crops with enhanced nutritional value.

  20. Surface aggregation of urinary proteins and aspartic acid-rich peptides on the faces of calcium oxalate monohydrate investigated by in situ force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, M L; Qiu, S R; Hoyer, J R; Casey, W H; Nancollas, G H; De Yoreo, J J

    2008-05-28

    The growth of calcium oxalate monohydrate in the presence of Tamm-Horsfall protein (THP), osteopontin (OPN), and the 27-residue synthetic peptides (DDDS){sub 6}DDD and (DDDG){sub 6}DDD [where D = aspartic acid and X = S (serine) or G (glycine)] was investigated via in situ atomic force microscopy (AFM). The results show that these three growth modulators create extensive deposits on the crystal faces. Depending on the modulator and crystal face, these deposits can occur as discrete aggregates, filamentary structures, or uniform coatings. These proteinaceous films can lead to either the inhibition or increase of the step speeds (with respect to the impurity-free system) depending on a range of factors that include peptide or protein concentration, supersaturation and ionic strength. While THP and the linear peptides act, respectively, to exclusively increase and inhibit growth on the (-101) face, both exhibit dual functionality on the (010) face, inhibiting growth at low supersaturation or high modulator concentration and accelerating growth at high supersaturation or low modulator concentration. Based on analyses of growth morphologies and dependencies of step speeds on supersaturation and protein or peptide concentration, we argue for a picture of growth modulation that accounts for the observations in terms of the strength of binding to the surfaces and steps and the interplay of electrostatic and solvent-induced forces at crystal surface.

  1. Mutagenesis of the aspartic acid ligands in human serum transferrin: lobe-lobe interaction and conformation as revealed by antibody, receptor-binding and iron-release studies.

    Science.gov (United States)

    Mason, A; He, Q Y; Tam, B; MacGillivray, R A; Woodworth, R

    1998-01-01

    Recombinant non-glycosylated human serum transferrin and mutants in which the liganding aspartic acid (D) in one or both lobes was changed to a serine residue (S) were produced in a mammalian cell system and purified from the tissue culture media. Significant downfield shifts of 20, 30, and 45 nm in the absorption maxima were found for the D63S-hTF, D392S-hTF and the double mutant, D63S/D392S-hTF when compared to wild-type hTF. A monoclonal antibody to a sequential epitope in the C-lobe of hTF reported affinity differences between the apo- and iron-forms of each mutant and the control. Cell-binding studies performed under the same buffer conditions used for the antibody work clearly showed that the mutated lobe(s) had an open cleft. It is not clear whether the receptor itself may play a role in promoting the open conformation or whether the iron remains in the cleft. PMID:9461487

  2. Primary deuterium isotope effects for the 3-methylaspartase-catalyzed deamination of (2S)-aspartic acid, (2S,3S)-3-ethylaspartic acid, and (2S,3S)-3-ethylaspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Botting, N.P.; Cohen, M.A.; Akhtar, M.; Gani, D.

    1988-04-19

    3-Methylaspartate ammonia-lyase catalyzes the deamination of (2S)-aspartic acid 137 times more slowly than the deamination of (2S,3S)-3-methylaspartic acid but catalyzes the amination of fumaric acid 1.8 times faster than the amination of mesaconic acid. In order to understand the mechanistic basis for these observations, the deamination reaction was examined kinetically with (2S)-aspartic acid, (2S,3S)-3-methylaspartic acid, (2S,3S)-3-ethylaspartic acid, and the corresponding C-3-deuteriated isotopomers. Comparison of the double-reciprocal plots of the initial reaction velocities for each of the three pairs of substrates revealed that the magnitude of the primary isotope effect on both V/sub max/ and VK varied with the substituent at C-3 of the substrate. These results, which are inconsistent with earlier reports that there is no primary isotope effect for 3-methylaspartic acid, suggest that for both 3-methylaspartic acid and 3-ethylaspartic acid elimination occurs via a predominantly concerted mechanism whereas for aspartic acid in El/sub cb/ mechanism prevails. It is expected that the change in mechanism arises as a result of the loss of the hydrophobic interaction between the C-3-alkyl substituent of the substrate and the complementary active site pocket of the enzyme, which leads to poor orbital alignment of the nascent negative charge with the C-N bond in the carbanion derived from aspartic acid. Substrate C-3 hydrogen exchange experiments suggest that the intermediate carbanionconjugate acid is not accessible to solvent during catalysis.

  3. Preservation of homochirality of aspartic acid films irradiated with 8.5 eV vacuum ultraviolet light

    Science.gov (United States)

    Izumi, Yudai; Matsui, Takahiro; Koketsu, Toshiyuki; Nakagawa, Kazumichi

    2008-10-01

    Enantiomeric excess was reported for amino acids detected from some meteorites. These results imply that these amino acids might escape from racemization processes in space. Here, in an attempt to examine whether non-polarized vacuum ultraviolet (VUV) light was one of racemization factors, we irradiated solid films of homochiral L- or D-aspartic acid ( L- or D-Asp) with a 146 nm excimer lamp in vacuum at 290 K. After irradiation for L-Asp films, L-alanine ( L-Ala) and β-Ala were observed, but D-Asp or D-Ala was not observed. On the contrast, for irradiation to D-Asp films, D-Ala and β-Ala were observed, but L-Asp or L-Ala was not observed. Therefore, we concluded that the chirality was preserved through the photolysis of Asp to Ala. It is of interest to carry out the similar experiments using high-energy particles and/or γ-ray irradiation.

  4. Preservation of homochirality of aspartic acid films irradiated with 8.5 eV vacuum ultraviolet light

    Energy Technology Data Exchange (ETDEWEB)

    Izumi, Yudai [Graduate School of Human Development and Environment, Kobe University, Nada-ku, Kobe 657-8501 (Japan)], E-mail: izumi@radix.h.kobe-u.ac.jp; Matsui, Takahiro; Koketsu, Toshiyuki [Graduate School of Cultural Studies and Human Science, Kobe University, Nada-ku, Kobe 657-8501 (Japan); Nakagawa, Kazumichi [Graduate School of Human Development and Environment, Kobe University, Nada-ku, Kobe 657-8501 (Japan); Graduate School of Cultural Studies and Human Science, Kobe University, Nada-ku, Kobe 657-8501 (Japan)], E-mail: nakagawa@kobe-u.ac.jp

    2008-10-15

    Enantiomeric excess was reported for amino acids detected from some meteorites. These results imply that these amino acids might escape from racemization processes in space. Here, in an attempt to examine whether non-polarized vacuum ultraviolet (VUV) light was one of racemization factors, we irradiated solid films of homochiral L- or D-aspartic acid (L- or D-Asp) with a 146 nm excimer lamp in vacuum at 290 K. After irradiation for L-Asp films, L-alanine (L-Ala) and {beta}-Ala were observed, but D-Asp or D-Ala was not observed. On the contrast, for irradiation to D-Asp films, D-Ala and {beta}-Ala were observed, but L-Asp or L-Ala was not observed. Therefore, we concluded that the chirality was preserved through the photolysis of Asp to Ala. It is of interest to carry out the similar experiments using high-energy particles and/or {gamma}-ray irradiation.

  5. Ligand-functionalized degradable polyplexes formed by cationic poly(aspartic acid)-grafted chitosan-cyclodextrin conjugates.

    Science.gov (United States)

    Song, Hai-Qing; Li, Rui-Quan; Duan, Shun; Yu, Bingran; Zhao, Hong; Chen, Da-Fu; Xu, Fu-Jian

    2015-03-19

    Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE-FA/pDNA, and ternary CCPE-FA/CCPE/pDNA (prepared by layer-by-layer assembly) polyplexes were investigated in detail using different cell lines. The CCPE-based polyplexes displayed much higher transfection efficiencies than the CS-based polyplexes reported earlier by us. The ternary polyplexes of CCPE-FA/CCPE/pDNA produced excellent gene transfection abilities in the folate receptor (FR)-positive tumor cells. This work would provide a promising means to produce highly efficient polyplexes for future gene therapy applications.

  6. Voltammetric determination of dopamine and norepinphrine on a glassy carbon electrode modified with poly (L-aspartic acid)

    Indian Academy of Sciences (India)

    Zhangyu Yu; Xiaochun Li; Xueliang Wang; Xinying Ma; Xia Li; Kewei Cao

    2012-03-01

    A convenient and useful method for the voltammetric determination of dopamine (DA) and norepinphrine (NE) based on poly(L-aspartic acid) modified glassy carbon electrode (GCE) is reported in this paper. The modified electrode exhibits excellent electro-catalytic activities for the oxidation-reduction of DA and NE, as well as eliminating the interference of ascorbic acid (AA) and uric acid (UA). Factors influencing the detection processes are optimized and the kinetic parameters are calculated. Under the optimal conditions, the anodic peak currents of DA and NE are linear with their concentration and the detection limits (S/N = 3) are 1.0 × 10−9 mol L-1 for DA and 4.31 10−9 mol L-1 for NE, respectively. The practical application of this method is demonstrated by determining the concentration of NE and DA in injection which is commercially available with satisfactory results. Compared with other electrochemical methods, this method is simple, highly selective and sensitive.

  7. Novel class of amino acid antagonists at non-N-methyl-D-aspartic acid excitatory amino acid receptors. Synthesis, in vitro and in vivo pharmacology, and neuroprotection

    Energy Technology Data Exchange (ETDEWEB)

    Krogsgaard-Larsen, P.; Ferkany, J.W.; Nielsen, E.O.; Madsen, U.; Ebert, B.; Johansen, J.S.; Diemer, N.H.; Bruhn, T.; Beattie, D.T.; Curtis, D.R. (Royal Danish School of Pharmacy, Copenhagen (Denmark))

    1991-01-01

    The isoxazole amino acid 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl) propionic acid (AMPA) (1), which is a highly selective agonist at the AMPA subtype of excitatory amino acid (EAA) receptors, has been used as a lead for the development of two novel EAA receptor antagonists. One of the compounds, 2-amino-3-(3-(carboxymethoxy)-5-methylisoxazol-4-yl)propionic acid (AMOA, 7), was synthesized via O-alkylation by ethyl chloroacetate of the amino acid protected AMPA derivative 4. The other compound, 2-amino-3-(2-(3-hydroxy-5-methylisoxazol-4-yl)-methyl-5-methyl-3-+ ++oxoisoxazolin -4-yl)propionic acid (AMNH, 14) was synthesized with use of 4-(chloromethyl)-3-methoxy-5-methylisoxazole (8) as the starting material. The intermediate 4-(chloromethyl)-2-(3-methoxy-5-methylisoxazol-4-yl)methyl-5-me thylisoxazolin- 3-one (11) was converted into the acetamidomalonate (12), which was stepwise deprotected to give 14. Compounds 7 and 14 were stable in aqueous solution at pH values close to physiological pH. Neither 7 nor 14 showed detectable affinities for the receptor, ion channel, or modulatory sites of the N-methyl-D-aspartic acid (NMDA) receptor complex. Quantitative receptor autoradiographic and conventional binding techniques were used to study the affinities of 7 and 14 for non-NMDA receptor sites. Both compounds were inhibitors of the binding of (3H)AMPA (IC50 = 90 and 29 microM, respectively). Compounds 14 and 7 were both very weak inhibitors of the high-affinity binding of radioactive kainic acid ((3H)KAIN). Compound 14, but not 7, was, however, shown to be an inhibitor of low-affinity (3H)KAIN binding as determined in the presence of 100 mM calcium chloride. In the rat cortical slice preparation, 7 was shown to antagonize excitation induced by 1 with some selectivity, whereas 14 proved to be a rather selective antagonist of KAIN-induced excitation.

  8. The antiallodynic action target of intrathecal gabapentin: Ca2+ channels, KATP channels or N-methyl-d-aspartic acid receptors?

    Science.gov (United States)

    Cheng, Jen-Kun; Chen, Chien-Chuan; Yang, Jia-Rung; Chiou, Lih-Chu

    2006-01-01

    Gabapentin is a novel analgesic whose mechanism of action is not known. We investigated in a postoperative pain model whether adenosine triphosphate (ATP)-sensitive K+ (K(ATP)) channels, N-methyl-d-aspartic acid (NMDA) receptors, and Ca2+ channels are involved in the antiallodynic effect of intrathecal gabapentin. Mechanical allodynia was induced by a paw incision in isoflurane-anesthetized rats. Withdrawal thresholds to von Frey filament stimulation near the incision site were measured before and after incision and after intrathecal drug administration. The antiallodynic effect of gabapentin (100 mug) was not affected by intrathecal pretreatment with antagonists of K(ATP) channels, NMDA receptors or gamma-aminobutyric acid (GABA)(A) receptors. K(ATP) channel openers and GABA(A) receptor agonist, per se, had little effect on the postincision allodynic response. The Ca2+ channel blocker of N-type (omega-conotoxin GVIA, 0.1-3 microg), but not of P/Q-type (omega-agatoxin IVA), L-type (verapamil, diltiazem or nimodipine), or T-type (mibefradil), attenuated the incision-induced allodynia, as did gabapentin. Both the antiallodynic effects of gabapentin and omega-conotoxin GVIA were attenuated by Bay K 8644, an L-type Ca2+ channel activator. These results provide correlative evidence to support the contention that N-type Ca2+ channels, but not K(ATP) channels or NMDA or GABA(A) receptors, might be involved in the antiallodynic effect of intrathecal gabapentin.

  9. Theoretical Study on the Activity of α-COOH and β-COOH of N-Phosphoryl Aspartic Acids

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between α-COOH and β-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates Ⅱ containing five-membered ring were more stable than Ⅲ with six-membered ring. While for intermediates Ⅲ, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states Ⅳ and V involving α-COOH or β-COOH group had energy barriers of ΔE = 58.67 kJ·mol-1 and 103.94 kJ·mol-1, respectively. These results were in agreement with the experimental data. So the α-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not β-COOH group.

  10. Synthesis and characterization of magnetic and luminescent Fe3O4/CdTe nanocomposites using aspartic acid as linker

    Institute of Scientific and Technical Information of China (English)

    Xiu Ling Wang; Lu Wei; Guan Hong Tao; Meng Qiong Huang

    2011-01-01

    In this study, the preparation of a new kind of magnetic and luminescent Fe3O4/CdTe nanocomposites was demonstrated. Superparamagnetic Fe3O4 nanoparticles were first synthesized by hydrothermal coprecipitation of ferric and ferrous ions, followed by the modification of their surfaces with tetramethylammonium hydroxide (TMAOH) and the chemical activation with aspartic acid. The surface-modified Fe3O4 nanoparticles were then covalently coated with CdTe quantum dots (QDs), which were modified with mercaptoacetic acid (MPA), to form the Fe3O4/CdTe magnetic and luminescent nanocomposites through the coordination of the amino groups on the surfaces of Fe3O4 and the carboxyl groups on CdTe QDs. The structure and properties of as-synthesized nanocomposites were characterized. It was indicated that the nanocomposites possessed structure with an average diameter of 40-50 nm, yellow-green emission feature and room temperature ferro-magnetism. Both the fluorescence and UV-vis absorption spectra of the nanocomposites showed a blue shift comparing with those of CdTe QDs. The mechanism of the blue shift was presented. The nanocomposites retained the ferromagnetic property with a saturation magnetization of 8.9 emu/g.

  11. How to find a leucine in a haystack? Structure, ligand recognition and regulation of leucine-aspartic acid (LD) motifs.

    Science.gov (United States)

    Alam, Tanvir; Alazmi, Meshari; Gao, Xin; Arold, Stefan T

    2014-06-15

    LD motifs (leucine-aspartic acid motifs) are short helical protein-protein interaction motifs that have emerged as key players in connecting cell adhesion with cell motility and survival. LD motifs are required for embryogenesis, wound healing and the evolution of multicellularity. LD motifs also play roles in disease, such as in cancer metastasis or viral infection. First described in the paxillin family of scaffolding proteins, LD motifs and similar acidic LXXLL interaction motifs have been discovered in several other proteins, whereas 16 proteins have been reported to contain LDBDs (LD motif-binding domains). Collectively, structural and functional analyses have revealed a surprising multivalency in LD motif interactions and a wide diversity in LDBD architectures. In the present review, we summarize the molecular basis for function, regulation and selectivity of LD motif interactions that has emerged from more than a decade of research. This overview highlights the intricate multi-level regulation and the inherently noisy and heterogeneous nature of signalling through short protein-protein interaction motifs.

  12. Enhancing microdialysis recovery of metal ions by incorporating poly-L-aspartic acid and poly-L-histidine in the perfusion liquid

    Energy Technology Data Exchange (ETDEWEB)

    Mogopodi, Dikabo; Torto, Nelson

    2003-04-10

    A study of the evaluation of poly-L-aspartic acid and poly-L-histidine as binding agents to enhance microdialysis recovery of metal ions is presented. Investigations were carried out to compare microdialysis recovery for Cr, Cu, Ni, and Pb when using water as the perfusion liquid as well as when using various concentrations of poly-L-aspartic acid and poly-L-histidine in the perfusion liquid. All experiments were carried out under quiescent conditions using a concentric type of microdialysis probe fitted with a polysulfone membrane having a 30 kDa molecular weight cut-off and a 10 mm effective dialysis length. The metal ions were determined using an electrothermal atomic absorption spectrometer equipped with a Zeemann background corrector. Incorporation of 0.032% (w/v) of poly-L-aspartic acid enhanced the recovery of Cu and Pb by factors of 90 and 64%, respectively (%RSD<3). The recovery of Cr was enhanced by 5%, but that of Ni never exceeded values achieved using ultra pure water. The use of 20% (w/v) of poly-L-histidine resulted in enhancement factors of 66 and 4% for Cu and Pb, respectively (%RSD<2). For both Cr and Ni, the recovery never exceeded that achieved with water. The data from these studies demonstrate the suitability of poly-L-aspartic and poly-L-histidine as selective and effective binding agents that enhance the microdialysis recovery of metal ions. Application of the optimised conditions to the determination of Pb and Cu in a wastewater sample confirmed the versatility of microdialysis, as higher recoveries of Cu were obtained with poly-L-aspartic acid compared to direct determination.

  13. Intramembrane aspartic acid in SCAP protein governs cholesterol-induced conformational change

    Science.gov (United States)

    Feramisco, Jamison D.; Radhakrishnan, Arun; Ikeda, Yukio; Reitz, Julian; Brown, Michael S.; Goldstein, Joseph L.

    2005-01-01

    The polytopic membrane protein SCAP transports sterol regulatory element-binding proteins (SREBPs) from the endoplasmic reticulum (ER) to the Golgi, thereby activating cholesterol synthesis. Cholesterol accumulation in the ER membranes changes SCAP to an alternate conformation in which it binds ER retention proteins called Insigs, thereby terminating cholesterol synthesis. Here, we show that the conserved Asp-428 in the sixth transmembrane helix of SCAP is essential for SCAP's dissociation from Insigs. In transfected hamster cells, mutant SCAP in which Asp-428 is replaced by alanine (D428A) remained in an Insig-binding conformation when cells were depleted of sterols. As a result, mutant SCAP failed to dissociate from Insigs, and it failed to carry SREBPs to the Golgi. These data identify an important functional residue in SCAP, and they provide genetic evidence that the conformation of SCAP dictates the rate of cholesterol synthesis in animal cells. PMID:15728349

  14. Simultaneous determination of D-aspartic acid and D-glutamic acid in rat tissues and physiological fluids using a multi-loop two-dimensional HPLC procedure.

    Science.gov (United States)

    Han, Hai; Miyoshi, Yurika; Ueno, Kyoko; Okamura, Chieko; Tojo, Yosuke; Mita, Masashi; Lindner, Wolfgang; Zaitsu, Kiyoshi; Hamase, Kenji

    2011-11-01

    For a metabolomics study focusing on the analysis of aspartic and glutamic acid enantiomers, a fully automated two-dimensional HPLC system employing a microbore-ODS column and a narrowbore-enantioselective column was developed. By using this system, a detailed distribution of D-Asp and D-Glu besides L-Asp and L-Glu in mammals was elucidated. For the total analysis concept, the amino acids were first pre-column derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) to be sensitively and fluorometrically detected. For the non-stereoselective separation of the analytes in the first dimension a monolithic ODS column (750 mm × 0.53 mm i.d.) was adopted, and a self-packed narrowbore-Pirkle type enantioselective column (Sumichiral OA-2500S, 250 mm × 1.5 mm i.d.) was selected for the second dimension. In the rat plasma, RSD values for intra-day and inter-day precision were less than 6.8%, and the accuracy ranged between 96.1% and 105.8%. The values of LOQ of D-Asp and D-Glu were 5 fmol/injection (0.625 nmol/g tissue). The present method was successfully applied to the simultaneous determination of free aspartic acid and glutamic acid enantiomers in 7 brain areas, 11 peripheral tissues, plasma and urine of Wistar rats. Biologically significant D-Asp values were found in various tissue samples whereas for D-Glu the values were very low possibly indicating less significance.

  15. Molecular cloning and enzymological characterization of pyridoxal 5'-phosphate independent aspartate racemase from hyperthermophilic archaeon Thermococcus litoralis DSM 5473.

    Science.gov (United States)

    Washio, Tsubasa; Kato, Shiro; Oikawa, Tadao

    2016-09-01

    We succeeded in expressing the aspartate racemase homolog gene from Thermococcus litoralis DSM 5473 in Escherichia coli Rosetta (DE3) and found that the gene encodes aspartate racemase. The aspartate racemase gene consisted of 687 bp and encoded 228 amino acid residues. The purified enzyme showed aspartate racemase activity with a specific activity of 1590 U/mg. The enzyme was a homodimer with a molecular mass of 56 kDa and did not require pyridoxal 5'-phosphate as a coenzyme. The enzyme showed aspartate racemase activity even at 95 °C, and the activation energy of the enzyme was calculated to be 51.8 kJ/mol. The enzyme was highly thermostable, and approximately 50 % of its initial activity remained even after incubation at 90 °C for 11 h. The enzyme showed a maximum activity at a pH of 7.5 and was stable between pH 6.0 and 7.0. The enzyme acted on L-cysteic acid and L-cysteine sulfinic acid in addition to D- and L-aspartic acids, and was strongly inhibited by iodoacetic acid. The site-directed mutagenesis of the enzyme showed that the essential cysteine residues were conserved as Cys83 and Cys194. D-Forms of aspartic acid, serine, alanine, and valine were contained in T. litoralis DSM 5473 cells.

  16. Ligand-functionalized degradable polyplexes formed by cationic poly(aspartic acid)-grafted chitosan-cyclodextrin conjugates

    Science.gov (United States)

    Song, Hai-Qing; Li, Rui-Quan; Duan, Shun; Yu, Bingran; Zhao, Hong; Chen, Da-Fu; Xu, Fu-Jian

    2015-03-01

    Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE-FA/pDNA, and ternary CCPE-FA/CCPE/pDNA (prepared by layer-by-layer assembly) polyplexes were investigated in detail using different cell lines. The CCPE-based polyplexes displayed much higher transfection efficiencies than the CS-based polyplexes reported earlier by us. The ternary polyplexes of CCPE-FA/CCPE/pDNA produced excellent gene transfection abilities in the folate receptor (FR)-positive tumor cells. This work would provide a promising means to produce highly efficient polyplexes for future gene therapy applications.Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE

  17. Synthesis and characterization of new optically active copoly(amid-imide)s based on N-phthalimido-L-aspartic acid and aromatic diamines

    Institute of Scientific and Technical Information of China (English)

    Khalil; Faghihi; Hamidreza; Alimohammadi

    2010-01-01

    In this article,six new optically active copoly(amide-imide)s(10a-f) were synthesized through the direct polycondensation reaction of N-phthalimido-L-aspartic acid(4) with 1,5-diamino naphthalene(8),3,4-diamino benzophenone(9) in the presence of therphthahc acid(7),fumaric acid(6) and adipic acid(5) as a second diacid in a medium consisting of N-methyl-2-pyrrolidone,triphenyl phosphite, calcium chloride and pyridine.The resulting copolymers were fully characterized by means of FT-IR spectroscopy,elementa...

  18. Study of L-aspartic acid for its possible use as a dosimeter in the interval of 3.4-20 kGy at different irradiation temperatures

    Science.gov (United States)

    Meléndez-López, Adriana; Negrón-Mendoza, Alicia; Gómez-Vidales, Virginia; Uribe, Roberto M.; Ramos-Bernal, Sergio

    2014-11-01

    Certain commercial applications of radiation processing increase the efficiency of chemical reactions at low temperatures to decrease the free radicals in the bulk material and avoid the synergistic effects of heat. Such applications have motivated the search for a reliable, low-temperature dosimeter for use under the conditions of the irradiation process. For this purpose, polycrystalline samples of L-aspartic acid (2-aminobutanedioic acid) were irradiated with gamma rays at low temperatures and doses in the kiloGray range (3.4-64 kGy). The potential use of the aspartic acid system as a chemical dosimeter is based on the formation of stable free radicals when the amino acid is exposed to ionizing radiation. These radicals can be studied and quantified using electron spin resonance (ESR). The response curves at different temperatures show that the intensity of the ESR spectra (the five characteristic lines) depends on the dose received. The response of the dosimeter increases with increasing temperature, and this relationship is linear up to 20 kGy at 298 K. The decay characteristics show that the change in the ESR signal over time is low and reproducible. In addition, the L-aspartic acid dosimeter is easy to handle and has low cost.

  19. Mutagenesis of aspartic acid-116 enhances the ribonucleolytic activity and angiogenic potency of angiogenin.

    Science.gov (United States)

    Harper, J W; Vallee, B L

    1988-01-01

    Site-specific mutagenesis of the blood vessel-inducing protein angiogenin has been used to further explore both its homology to pancreatic ribonuclease and the functional roles of particular residues. Replacement of Asp-116 in angiogenin by either asparagine (D116N), alanine (D116A), or histidine (D116H) markedly enhances both its ribonucleolytic activity and angiogenic potency. Activity toward tRNA is 8-, 15-, and 18-fold greater than native angiogenin for D116N-, D116A-, and D116H-angiogenin, respectively. The enzymatic specificity of angiogenin, however, has been maintained. Thus, cleavage of 18S and 28S rRNA by the most active His-116 mutant yields the same pattern of polynucleotide products as from angiogenin, whereas there are only minor alterations in activity with cytidylyl(3',5')adenosine and uridylyl(3',5')-adenosine. Extensive biological assays on the chicken embryo chorioallantoic membrane demonstrate that D116H-angiogenin is one to two orders of magnitude more potent in inducing neovascularization than native angiogenin, which correlates well with enhanced enzymatic action. These results support the proposition that the enzymatic and angiogenic activities on angiogenin are interrelated. PMID:2459697

  20. Enantioselective micro-2D-HPLC determination of aspartic acid in the pineal glands of rodents with various melatonin contents.

    Science.gov (United States)

    Han, Hai; Miyoshi, Yurika; Oyama, Tsubasa; Konishi, Ryoko; Mita, Masashi; Hamase, Kenji

    2011-10-01

    Enantioselective determination of aspartic acid (Asp) in the pineal gland of rodents with various melatonin contents was performed using a highly sensitive and selective two-dimensional HPLC system. After derivatization of the amino group with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), NBD-Asp was separated using a capillary monolithic ODS column in the first dimension. The fraction of NBD-Asp was automatically collected and transferred to the second dimension, and the D- and L-Asp were separated and determined using a narrowbore enantioselective column. Large amounts of D-Asp were observed in the pineal gland of the rats and specific strains of mice (C3H and CBA) possessing a high concentration of melatonin in their pineal gland. On the other hand, the amounts of D-Asp were small in the pineal gland of mice possessing a trace or no melatonin in their pineal gland (ddY, ICR, C57BL and BALB/c). In other tissues and physiological fluids, no significant strain-dependent changes of the D-Asp amounts were observed. These results indicate that large amounts of D-Asp are present only in the pineal gland containing large amounts of melatonin, and special care should be taken when selecting mouse strains for the investigation of D-Asp.

  1. Protective effects of PF-4708671 against N-methyl-d-aspartic acid-induced retinal damage in rats.

    Science.gov (United States)

    Hayashi, Ikumi; Aoki, Yuto; Ushikubo, Hiroko; Asano, Daiki; Mori, Asami; Sakamoto, Kenji; Nakahara, Tsutomu; Ishii, Kunio

    2016-12-01

    We previously demonstrated that rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), protects against N-methyl-d-aspartic acid (NMDA)-induced retinal damage in rats. Rapamycin inhibits mTOR activity, thereby preventing the phosphorylation of ribosomal protein S6, which is a downstream target of S6 kinase. Therefore, we aimed to determine whether PF-4708671, an inhibitor of S6 kinase, protects against NMDA-induced retinal injury. Intravitreal injection of NMDA (200 nmol/eye) caused cell loss in the ganglion cell layer and neuroinflammatory responses, such as an increase in the number of CD45-positive leukocytes and Iba1-positive microglia. Surprisingly, simultaneous injection of PF-4708671 (50 nmol/eye) with NMDA significantly attenuated these responses without affecting phosphorylated S6 levels. These results suggest that PF-4708671 and rapamycin likely protect against NMDA-induced retinal damage via distinct pathways. The neuroprotective effect of PF-4708671 is unlikely to be associated with inhibition of the S6 kinase, even though PF-4708671 is reported to be a S6 kinase inhibitor.

  2. The effect of the antioxidant on the properties of thiolated poly(aspartic acid) polymers in aqueous ocular formulations.

    Science.gov (United States)

    Budai-Szűcs, Mária; Horvát, Gabriella; Gyarmati, Benjámin; Szilágyi, Barnabás Áron; Szilágyi, András; Berkó, Szilvia; Ambrus, Rita; Szabó-Révész, Piroska; Sandri, Giuseppina; Bonferoni, Maria Cristina; Caramella, Carla; Csányi, Erzsébet

    2017-04-01

    Thiolated polymers are a promising new group of excipients, but their stability against atmospheric oxidation has not been investigated in detail, and only a few efforts have been made to improve their stability. The oxidation of the thiol groups in solutions of thiolated polymers may result in a decrease of mucoadhesion and unpredictable in situ gelation. The aims of our work were to study the stability of aqueous solutions of thiolated polymers and the effects of stabilizing agents. We investigated thiolated poly(aspartic acid) polymers stabilized with dithiothreitol, glutathione or acetylcysteine. The effects of these antioxidants on the gel structure, mucoadhesion and drug release were determined by means of scanning electron microscopy, swelling, rheology, adhesion and drug release tests. It was concluded that the stability of polymer solutions containing antioxidants is sufficient for one day. Polymers stabilized with dithiotreitol demonstrated fast swelling and drug release, but weaker mucoadhesion as compared with the other samples. Polymers stabilized with glutathione displayed the weakest cohesive properties, resulting in fast and uncontrolled drug release and moderate mucoadhesion. Acetylcysteine-stabilized polymers exhibited an optimum cross-linked structure, with free thiol groups ensuring polymer-mucin interactions, resulting in the best mucoadhesive properties.

  3. Relation between etch-pit morphology and step retreat velocity on a calcite surface in aspartic acid solution

    Science.gov (United States)

    Yoshino, Toru; Kagi, Hiroyuki; Kamiya, Natsumi; Kokawa, Ryohei

    2010-04-01

    Effects of L-aspartic acid ( L-Asp) on dissolution of calcite were investigated. The step retreat velocity and dissolution rate of calcite were measured simultaneously using an AFM flow-through system. The etch-pit morphology of calcite was observed using confocal laser scanning microscopy. Results show that the etch-pit morphologies changed drastically depending on the L-Asp concentration ([ L-Asp]) in the order of rhomboidal, pentagonal, and triangular (not perfectly, but retaining an extra step). The change in obtuse step directions and appearance of the [0 1 0] step triggered these morphological changes. Addition of L-Asp accelerated all step retreats at [ L-Asp]0.01 M, L-Asp inhibited the retreats of obtuse steps and [0 1 0] step, although the retreat velocities of acute steps were constant irrespective of [ L-Asp]. These results suggest that the directional changes and the inhibition of retreat velocities of obtuse steps were attributed to the generation of [ 4 1 1] and [4 5 1] steps caused by L-Asp. Moreover, we confirmed the preferential effects of L-Asp on the [4 8 1] + to [ 4 4 1] ± step edge, and proposed the preferential effects of L-Asp on the [ 4 1 1] to [4 5 1] step edge.

  4. Aspartic acid at position 57 of the HLA-DQ beta chain protects against type I diabetes: a family study.

    Science.gov (United States)

    Morel, P A; Dorman, J S; Todd, J A; McDevitt, H O; Trucco, M

    1988-01-01

    One hundred seventy-two members from 27 randomly selected multiple case Caucasian families of patients with insulin-dependent diabetes mellitus (IDDM) were studied at the DNA level to ascertain the reliability of codon 57 of the HLA-DQ beta-chain gene as a disease protection/susceptibility marker. The analysis was carried out by polymerase chain reaction amplification of DNA encoding the first domain of the DQ beta chain and by dot blot analysis of the amplified material with allele-specific oligonucleotide probes. One hundred twenty-three randomly selected healthy Caucasian donors were also tested. The results demonstrated that haplotypes carrying an aspartic acid in position 57 (Asp-57) of their DQ beta chain were significantly increased in frequency among nondiabetic haplotypes (23/38), while non-Asp-57 haplotypes were significantly increased in frequency among diabetic haplotypes (65/69). Ninety-six percent of the diabetic probands in our study were homozygous non-Asp/non-Asp as compared to 19.5% of healthy unrelated controls. This conferred a relative risk of 107 (chi 2 = 54.97; P = 0.00003) for non-Asp-57 homozygous individuals. Even though the inheritance and genetic features of IDDM are complex and are not necessarily fully explained by DQ beta chain polymorphism, this approach is much more sensitive than HLA serolog in assessing risk for IDDM. PMID:3186714

  5. Kinetics and Mechanism of Electron Transfer to Heptavalent Manganese by DL-Aspartic Acid in Alkaline Aqueous and Micellar Media

    Directory of Open Access Journals (Sweden)

    M. Sanjana

    2013-01-01

    Full Text Available The kinetics and mechanism of the electron transfer of dl-Aspartic acid (Asp by Mn (VII in alkaline medium has been studied spectrophotometrically over the range 2.0≤103[Asp] ≤5.0 mol dm−3; 0.01≤[OH-]≤0.05 mol dm−3; 298≤T≤318 K and I=0.05 mol dm−3 (KNO3. The reaction exhibits first-order dependence in [MnO4-]T but shows fractional-order dependence in both [Asp]T and [OH−]T. The reaction was studied in the presence of sodium dodecyl sulfate (SDS; an increase in the rate with the increase in the micellar concentration was observed. The products were characterized by spectral analysis. A mechanism involving free radicals is proposed. Asp binds MnO4- to form a complex that subsequently decomposes to products. Activation parameters ΔH° (kJ mol−1 and ΔS° (JK−1 mol−1 for the reaction are 5.62 ± 0.35 and −227.65 ± 1.1, respectively. The negative value of ΔS° indicates that oxidation occurs via inner sphere mechanism.

  6. Cyclen Grafted with poly[(Aspartic acid)-co-Lysine]: Preparation, Assembly with Plasmid DNA, and in Vitro Transfection Studies.

    Science.gov (United States)

    Ma, Chunying; Zhang, Jin; Guo, Liwen; Du, Changguo; Song, Ping; Zhao, Baojing; Li, Ling; Li, Chao; Qiao, Renzhong

    2016-01-04

    Development of safe and effective gene carriers is the key to the success of gene therapy. Nowadays, it is still required to develop new methods to improve nonviral gene delivery efficiency. Herein, copolymers of poly[(aspartic acid)-co-lysine] grafted with cyclen (cyclen-pAL) were designed and evaluated for efficient gene delivery. Two copolymers with different Asp/Lys block ratios were prepared and characterized by NMR and gel permeation chromatography analysis. Agarose gel retardation, circular dichroism, and fluorescent quenching assays showed the strong DNA-binding and protection ability for the title compounds. Atomic force microscopy studies clearly delineated uniform DNA globules with a diameter around 100 nm, induced by cyclen-pAL. By grafting cyclen on Asp, relatively high gene delivery efficiency and low cytotoxicity of the modified copolymers were achieved compared with their parent compounds. The present work might help to develop strategies for design and modification of polypeptide copolymers, which may also be applied to favorable gene expression and delivery.

  7. Effect of poly(aspartic acid) on calcium phosphate removal from stainless steel tubing under turbulent flow conditions

    Science.gov (United States)

    Littlejohn, Felicia

    Calcium phosphate deposition causes cleaning problems in a number of situations including water treatment, dairy processing, and dental applications. This problem is exacerbated by the limited choices of cleaning chemicals that meet environmental regulations. To promote the development of biodegradable, non-toxic alternatives, this research examines the removal of calcium phosphate deposits consisting of brushite (dicalcium phosphate dihydrate; DCPD) and a mixture of hydroxyapatite (HAP) and DCPD from stainless steel in the presence of poly(aspartic acid) and its sodium salt (PASP). The effects of solvent pH, PASP concentration, and flow rate on the calcium phosphate removal rates are measured from stainless steel tubing under turbulent flow conditions using a solid scintillation detection technique. A mechanistic evaluation of the cleaning data in the absence of PASP indicates that DCPD removal is dominated by shear while HAP/DCPD deposit removal is limited by a combination of mass transfer and interfacial processes. Although the removal mechanisms differ, the results conclusively show that PASP promotes calcium phosphate removal under conditions that favor calcium sequestration in both cases. An in-depth study of DCPD removal in the presence of PASP reveals that this additive is most effective under conditions where calcium sequestration and phosphate protonation occur simultaneously.

  8. How to find a leucine in a haystack? Structure, ligand recognition and regulation of leucine-aspartic acid (LD) motifs

    KAUST Repository

    Alam, Tanvir

    2014-05-29

    LD motifs (leucine-aspartic acidmotifs) are short helical protein-protein interaction motifs that have emerged as key players in connecting cell adhesion with cell motility and survival. LD motifs are required for embryogenesis, wound healing and the evolution of multicellularity. LD motifs also play roles in disease, such as in cancer metastasis or viral infection. First described in the paxillin family of scaffolding proteins, LD motifs and similar acidic LXXLL interaction motifs have been discovered in several other proteins, whereas 16 proteins have been reported to contain LDBDs (LD motif-binding domains). Collectively, structural and functional analyses have revealed a surprising multivalency in LD motif interactions and a wide diversity in LDBD architectures. In the present review, we summarize the molecular basis for function, regulation and selectivity of LD motif interactions that has emerged from more than a decade of research. This overview highlights the intricate multi-level regulation and the inherently noisy and heterogeneous nature of signalling through short protein-protein interaction motifs. © 2014 Biochemical Society.

  9. Recovery from severe frontotemporal dysfunction at 3years after N-methyl-d-aspartic acid (NMDA) receptor antibody encephalitis.

    Science.gov (United States)

    Leypoldt, Frank; Gelderblom, Mathias; Schöttle, Daniel; Hoffmann, Sascha; Wandinger, Klaus-Peter

    2013-04-01

    Encephalitis associated with antibodies against N-methyl-d-aspartic acid (NMDA) receptor is characterized by severe memory deficits, decreased consciousness, epileptic seizures and movement disorders and occurs most commonly in young women. Recovery is mostly good but little is known about the disease course in patients whose treatment has been delayed severely. We present a 16-year-old girl with a 36-month follow-up. A single course of methylprednisolone attenuated some symptoms but severe and incapacitating frontotemporal syndrome remained. Second-line treatment with rituximab was initiated 12months after the onset of symptoms. A surprising recovery occurred 18months after treatment and 30months after onset. Recovery in NMDA receptor antibody-associated encephalitis can be severely delayed and does not have to be linear. Whether delayed therapy contributed to recovery in this patient cannot be answered with certainty. Spontaneous recovery independent of therapy is possible, as it has been observed previously as late as 3years after onset. Although serum antibodies disappeared with recovery in this patient, previous cases have shown serum antibodies to be unreliable markers of disease activity. Second-line treatment, especially with substances as well tolerated as rituximab, should at least be considered in NMDA receptor encephalitis with persistent neuropsychiatric syndromes after first-line therapy.

  10. Maximising metal ions flux across a microdialysis membrane by incorporating poly-L-aspartic acid, poly-L-histidine, 8-hydroxyquinoline and ethylenediaminetetraacetic acid in the perfusion liquid

    Energy Technology Data Exchange (ETDEWEB)

    Mogopodi, Dikabo [University of Botswana, Department of Chemistry, Private Bag UB 00704, Gaborone (Botswana); Torto, Nelson [University of Botswana, Department of Chemistry, Private Bag UB 00704, Gaborone (Botswana)]. E-mail: torton@mopipi.ub.bw

    2005-04-08

    This paper presents a study of quiescent microdialysis sampling of Cr{sup 3+}, Cu{sup 2+}, Ni{sup 2+} and Pb{sup 2+} involving the incorporation of poly-L-aspartic acid, poly-L-histidine, 8-hydroxyquinoline (8-HQ) and ethylenediaminetetraacetic acid (EDTA), in the perfusion liquid as an approach to maximise metal analyte flux across the microdialysis membrane. These chelating agents were individually optimised with respect to microdialysis recovery and subsequently combined in the perfusion liquid. A combination of 20% (w/v) poly-L-histidine, 0.032% (w/v) poly-L-aspartic acid and 1 mM 8-HQ achieved microdialysis recovery up to 90%. Since 1 mM EDTA achieved recoveries greater than 80% for all metals understudy, EDTA was not combined with any of the chelating agents. Under the optimal conditions of maximum metal ion flux across the microdialysis membrane, metal ions from natural and wastewater were sampled and analysed with an electrothermal atomic absorption spectrometer equipped with a Zeeman background corrector. Results showed higher concentrations of detected metal ions after microdialysis sampling compared to direct detection without sample clean-up. Incorporation of chelating agents in the microdialysis perfusion liquid enhanced metal ions recovery in real samples and achieved enrichment factors of up to 42. The study demonstrated that combining chelating agents is a good approach towards maximising metal flux across the dialysis membrane. Given that recoveries between 80 and 90% were achieved under quiescent microdialysis sampling conditions, these findings are an important development for in vivo diagnostic sampling of metal ions.

  11. Amphoteric surfactants containing ?-hydroxy ester group and an amino acid residue

    Directory of Open Access Journals (Sweden)

    Eissa, A. M. F.

    2006-09-01

    Full Text Available A series of amphoteric surfactants containing α-hydroxy ester group and an amino acid residue were prepared with the addition of epoxy derivatives (which were prepared from epoxidation of alkyl methacrylate to different types of amino acids (glycine, alanine, valine, isoleucine, phenylalanine, tyrosine, serine, threonine, aspartic and anthranilic acid.The structures of the prepared compounds were confirmed by infrared spectra, proton magnetic resonance spectra, Mass spectra and elementary analysis. Surface tension, Kraft point, foaming power, critical micelle concentration emulsion and Ca++ stabilities were determined. Antimicrobial activity and biodegradability were also screened.Se prepararon una serie de tensioactivos anfóteros conteniendo un grupo alfa hidroxi éster y un residuo de aminoácido por adición de derivados epoxy (obtenidos mediante epoxidación de metacrilato de alquilo a diferentes tipos de aminoácidos (glicina, alanina, valina, isoleucina, fenilalanina, tirosina, serina, treonina y ácidos aspártico y antranílico. Las estructuras de los compuestos preparados se confirmaron por los espectros de infrarrojo, de masa, resonancia magnética nuclear de protones y análisis elemental. Se determinaron la tensión superficial, el punto de Kraft, el poder espumante, la concentración micelar crítica en emulsión y las estabilidades de Ca++. También se estudiaron la actividad antimicrobiana y la biodegradabilidad.

  12. Interaction of aspartic acid-104 and proline-287 with the active site of m-calpain.

    Science.gov (United States)

    Arthur, J S; Elce, J S

    1996-01-01

    In an ongoing study of the mechanisms of calpain catalysis and Ca(2+)-induced activation, the effects of Asp-104-->Ser and Pro-287-->Ser large subunit mutations on m-calpain activity, the pH-activity profile, Ca(2+)-sensitivity, and autolysis were measured. The importance of these positions was suggested by sequence comparisons between the calpain and papain families of cysteine proteinases. Asp-104 is adjacent to the active-site Cys-105, and Pro-287 is adjacent to the active-site Asn-286 and probably to the active-site His-262; both Asp-104 and Pro-287 are absolutely conserved in the known calpains, but are replaced by highly conserved serine residues in the papains. The single mutants had approx. 10-15% of wild-type activity, due mainly to a decrease in kcat, since Km was only slightly increased. The Pro-287-->Ser mutation appeared to cause a local perturbation of the catalytic Cys-105/His-262 catalytic ion pair, reducing its efficiency without major effect on the conformation and stability of the enzyme. The Asp-104-->Ser mutation caused a marked narrowing of the pH-activity curve, a 9-fold increase in Ca2+ requirement, and an acceleration of autolysis, when compared with the wild-type enzyme. The results indicated that Asp-104 alters the nature of its interaction with the catalytic ion pair during Ca(2+)-induced conformational change in calpain. This interaction may be direct or indirect, but is important in activation of the enzyme. PMID:8912692

  13. Nanofiltration of L-phenylalanine and L-aspartic acid aqueous solution and its process simulation%苯丙氨酸和天冬氨酸水溶液的纳滤分离及其过程模拟

    Institute of Scientific and Technical Information of China (English)

    王晓琳; 营爱玲

    2001-01-01

    选择苯丙氨酸和天冬氨酸水溶液进行了纳滤分离过程研究,讨论了不同pH下氨基酸的透过特性,并就该体系的浓缩分离进行了模拟计算.%The permeation experiments of aqueous solution of amino acids (L-phenylalanine and L-Aspartic acid) were carried out with nanofiltration membranes. The rejections of phenylalanine and aspartic acid are about 0 and 90%, respectively. The results show that the amino acids having large differences of isoelectric points (pI) can be separated satisfactorily by adjusting the value of pH. Then the concentration and separation process of phenylalanine and aspartic acid solution was simulated. A batchwise concentration and diafiltration system was designed. The results show that it is feasible to separate phenylalanine and aspartic acid in viewpoint of technology.

  14. A One-Bead-One-Catalyst Approach to Aspartic Acid-Based Oxidation Catalyst Discovery

    Science.gov (United States)

    Lichtor, Phillip A.; Miller, Scott J.

    2011-01-01

    We report an approach to the high-throughput screening of asymmetric oxidation catalysts. The strategy is based on application of the one-bead-one-compound library approach, wherein each of our catalyst candidates is based on a peptide scaffold. For this purpose we rely on a recently developed catalytic cycle that employs an acid-peracid shuttle. In order to implement our approach, we developed a compatible linker and demonstrated that the library format is amenable to screening and sequencing of catalysts employing partial Edman degradation and MALDI mass spectrometry analysis. The system was applied to the discovery (and re-discovery) of catalysts for the enantioselective oxidation of a cyclohexene derivative. The system is now poised for application to unprecedented substrate classes for asymmetric oxidation reactions. PMID:21417485

  15. Identification of protein SUMOylation sites by mass spectrometry using combined microwave-assisted aspartic acid cleavage and tryptic digestion

    Science.gov (United States)

    Osula, Omoruyi; Swatkoski, Stephen; Cotter, Robert J.

    2012-01-01

    SUMO (Small-Ubiquitin-like MOdifier) is a post-translational modifier of protein substrates at lysine residues that conjugates to proteins in response to various changes in the cell. As a result of SUMO modification, marked changes in transcription regulation, DNA repair, subcellular localization, and mitosis, among other cellular processes, are known to occur. However, while the identification of ubiquitylation sites by mass spectrometry is aided in part by the presence of a small di-amino acid GlyGly “tag” that remains on lysine residues following tryptic digestion, SUMOylation poses a particular challenge as the absence of a basic residue near to the SUMO C-terminus results in a significant 27 or 32 amino acid sequence branch conjugated to the substrate peptide. MS/MS analyses of these branch peptides generally reveal abundant fragment ions resulting from cleavage of the SUMO tail, but which obscure those needed for characterizing the target peptide sequence. Other approaches for identifying SUMO substrates exist and include overexpression of the SUMO isoforms using an N-terminal histidine tag, as well as site-directed mutagenesis of the C-terminal end of the SUMO sequence. Here, we employ combined enzymatic/chemical approaches which serve to shorten the SUMO tag, and thus help to simplify SUMO spectra, making interpretation of mass spectra and location of the SUMOylation site easier. As described in this report, we demonstrate a method for identifying SUMOylation sites using three commercially available SUMO- modified isoforms, and by employing acid-only and acid/trypsin cleavage strategies. These approaches were carried out using MALDI-TOF and LC/MS instrumentation, along with CID and ETD fragmentation. PMID:22576878

  16. Microsecond Deprotonation of Aspartic Acid and Response of the α/β Subdomain Precede C-Terminal Signaling in the Blue Light Sensor Plant Cryptochrome.

    Science.gov (United States)

    Thöing, Christian; Oldemeyer, Sabine; Kottke, Tilman

    2015-05-13

    Plant cryptochromes are photosensory receptors that regulate various central aspects of plant growth and development. These receptors consist of a photolyase homology region (PHR) carrying the oxidized flavin adenine dinucleotide (FAD) cofactor, and a cryptochrome C-terminal extension (CCT), which is essential for signaling. Absorption of blue/UVA light leads to formation of the FAD neutral radical as the likely signaling state, and ultimately activates the CCT. Little is known about the signal transfer from the flavin to the CCT. Here, we investigated the photoreaction of the PHR by time-resolved step-scan FT-IR spectroscopy complemented by UV-vis spectroscopy. The first spectrum at 500 ns shows major contributions from the FAD anion radical, which is demonstrated to then be protonated by aspartic acid 396 to the neutral radical within 3.5 μs. The analysis revealed the existence of three intermediates characterized by changes in secondary structure. A marked loss of β-sheet structure is observed in the second intermediate evolving with a time constant of 500 μs. This change is accompanied by a conversion of a tyrosine residue, which is identified as the formation of a tyrosine radical in the UV-vis. The only β-sheet in the PHR is located within the α/β subdomain, ∼25 Å away from the flavin. This subdomain has been previously attributed a role as a putative antenna binding site, but is now suggested to have evolved to a component in the signaling of plant cryptochromes by mediating the interaction with the CCT.

  17. L-天门冬氨酸-β-苄酯的制备研究%Synthesis and characterization of L-aspartic acid-β-benzyl ester

    Institute of Scientific and Technical Information of China (English)

    王昌济; 王永秋

    2013-01-01

    L-aspartic acid and benzyl alcohol as raw materials, studied on the synthesis of L-aspartic acid-/3-benzyl ester. The results showed that the best experimental conditions was; the concentrated sulfuric acid as catalyst,n (L-aspartic acid) : n (benzyl alcohol) = 1 : 10,100℃ reflux reaction 3 h,placed at room temperature 24 h, in this condition, the yield was about 60% .%以L-天门冬氨酸和苯甲醇为原料,对L-天门冬氨酸-β-苄酯的合成进行了研究.结果表明,较佳实验条件是:以浓硫酸为催化剂,n(L-天门冬氨酸)∶n(苯甲醇)=1∶10,100℃回流反应3h,室温放置24h,在该条件下,产率约60%.

  18. Amendment of Acid Soils with Crop Residues and Biochars

    Institute of Scientific and Technical Information of China (English)

    YUAN Jin-Hua; XU Ren-Kou; WANG Ning; LI Jiu-Yu

    2011-01-01

    The liming potential of some crop residues and their biochars on an acid Ultisol was investigated using incubation experiments. Rice hulls showed greater liming potential than rice hull biochar, while soybean and pea straws had less liming potential than their biochars. Due to their higher alkalinity, biochars from legume materials increased soil pH much compared to biochars from non-legume materials. The alkalinity of biochars was a key factor affecting their liming potential,and the greater alkalinity of biochars led to greater reductions in soil acidity. The incorporation of biochars decreased soil exchangeable acidity and increased soil exchangeable base cations and base saturation, thus improving soil fertility.

  19. Partial purification and characterization of an inducible indole-3-acetyl-L-aspartic acid hydrolase from Enterobacter agglomerans

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Jyh-Ching [Department of Agriculture, Beltsville, MD (United States)]|[Univ. of Maryland, College Park, MD (United States); Cohen, J.D.; Mulbry, W.W. [Department of Agriculture, Beltsville, MD (United States)] [and others

    1996-11-01

    Indole-3-acetyl-amino acid conjugate hydrolases are believed to be important in the regulation of indole-3-acetic acid (IAA) metabolism in plants and therefore have potential uses for the alteration of plant IAA metabolism. To isolate bacterial strains exhibiting significant indole-3-acetyl-aspartate (IAA-Asp) hydrolase activity, a sewage sludge inoculation was cultured under conditions in which IAA-Asp served as the sole source of carbon and nitrogen. One isolate, Enterobacter agglomerans, showed hydrolase activity inducible by IAA-L-Asp or N-acetyl-L-Asp but not by IAA, (NH{sub 4}){sub 2}SO{sub 4}, urea, or indoleacetamide. Among a total of 17 IAA conjugates tested as potential substrates, the enzyme had an exclusively high substrate specificity for IAA-L-Asp of 13.5 mM. The optimal pH for this enzyme was between 8.0 and 8.5. In extraction buffer containing 0.8 mM Mg{sup 2+} the hydrolase activity was inhibited to 80% by 1 mM dithiothreitol and to 60% by 1 mm CuSO{sub 4}; the activity was increased by 40% with 1mM MnSO{sub 4}. However, in extraction buffer with no trace elements, the hydrolase activity was inhibited to 50% by either 1 mM dithiothreitol or 1% Triton X-100 (Sigma). These results suggest that disulfide bonding might be essential for enzyme activity. Purification of the hydrolase by hydroxyapatite and TSK-phenyl (HP-Genenchem, South San Francisco, CA) preparative high-performance liquid chromatography yielded a major 45-kD polypeptide as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 45 refs., 5 figs., 3 tabs.

  20. Lactic Acid and Biosurfactants Production from Residual Cellulose Films.

    Science.gov (United States)

    Portilla Rivera, Oscar Manuel; Arzate Martínez, Guillermo; Jarquín Enríquez, Lorenzo; Vázquez Landaverde, Pedro Alberto; Domínguez González, José Manuel

    2015-11-01

    The increasing amounts of residual cellulose films generated as wastes all over the world represent a big scale problem for the meat industry regarding to environmental and economic issues. The use of residual cellulose films as a feedstock of glucose-containing solutions by acid hydrolysis and further fermentation into lactic acid and biosurfactants was evaluated as a method to diminish and revalorize these wastes. Under a treatment consisting in sulfuric acid 6% (v/v); reaction time 2 h; solid liquid ratio 9 g of film/100 mL of acid solution, and temperature 130 °C, 35 g/L of glucose and 49% of solubilized film was obtained. From five lactic acid strains, Lactobacillus plantarum was the most suitable for metabolizing the glucose generated. The process was scaled up under optimized conditions in a 2-L bioreactor, producing 3.4 g/L of biomass, 18 g/L of lactic acid, and 15 units of surface tension reduction of a buffer phosphate solution. Around 50% of the cellulose was degraded by the treatment applied, and the liqueurs generated were useful for an efficient production of lactic acid and biosurfactants using L. plantarum. Lactobacillus bacteria can efficiently utilize glucose from cellulose films hydrolysis without the need of clarification of the liqueurs.

  1. Inhibition mechanism analysis & research of the poly aspartic acid corrosion inhibitor%聚天冬氨酸缓蚀剂缓蚀机理分析研究

    Institute of Scientific and Technical Information of China (English)

    王娴

    2012-01-01

    文中介绍了聚天冬氨酸缓蚀剂缓蚀机理,并对聚天冬氨酸缓蚀剂机理的研究现状以及发展趋势进行了综述。%It was introduced inhibition mechanism of the poly aspartic acid corrosion inhibitor. Mean- while, it was summarizeed the research progress of the inhibition meehanismf the poly aspartic acid cor- rosion inhibitor and the development trend of the poly aspartic acid corrosion inhibitor in this article.

  2. Crystal growth of calcium carbonate on the cellulose acetate/pyrrolidon blend films in the presence of L-aspartic acid

    Science.gov (United States)

    Zhang, Xiuzhen; Xie, Anjian; Huang, Fangzhi; Shen, Yuhua

    2014-03-01

    The morphogenesis and growth process of calcium carbonate on the cellulose acetate/polyvinyl pyrrolidone (CA/PVP) blend films in the presence of L-aspartic acid was carefully investigated. The results showed that the concentration of L-aspartic acid, the initial pH value of reaction solution and temperature turned out to be important factors for the control of morphologies and polymorphs of calcium carbonate. Complex morphologies of CaCO3 particles, such as cubes, rose-like spheres, twinborn-spheres, cone-like, bouquet-like, etc. could be obtained under the different experimental conditions. The dynamic process of formation of rose-like sphere crystals was analyzed by monitoring the continuous morphological and structural evolution and components of crystals in different crystal stages. This research may provide a promising method to prepare other inorganic materials with complex morphologies.

  3. Effect of L-aspartic acid on the growth, structure and spectral studies of Zinc (tris) Thiourea Sulphate (ZTS) single crystals

    Science.gov (United States)

    Samuel, Bincy Susan; Krishnamurthy, R.; Rajasekaran, R.

    2014-11-01

    Single crystals of pure and L-aspartic acid doped Zinc (Tris) Thiourea Sulphate (ZTS) were grown from aqueous solution by solution growth method. The cell parameters and structure of the grown crystals were determined by X-ray diffraction studies. The presence of functional group in the compound has been confirmed by FTIR and FT-Raman analysis. The optical transparency range has been studied through UV-Vis spectroscopy. TGA/DTA studies show thermal stability of the grown crystals. Microhardness study reveals that the hardness number (Hv) increases with load for pure and doped ZTS crystals. Dielectric studies have been carried out and the results are discussed. The second harmonic generation was confirmed for L-aspartic acid doped ZTS which is greater than pure ZTS.

  4. The thermodynamic characteristics of complex formation of Cd2+ with N,N-Bis(carboxymethyl)aspartic acid in aqueous solutions at 298.15 K

    Science.gov (United States)

    Lytkin, A. I.; Chernyavskaya, N. V.; Litvinenko, V. E.

    2011-01-01

    The equilibrium constants and heats of formation of complexes of N,N-bis(carboxymethyl)aspartic acid (H4Y) with Cd2+ ions at 298.15 K and ionic strengths of 0.2, 0.5, and 1.0 (KNO3) were determined by potentiometric titration and calorimetrically. The thermodynamic characteristics of formation of the CdY2- complex at fixed and zero ionic strength values were calculated. The values obtained were interpreted.

  5. 天冬氨酸制备技术的研究进展%Progress on the Synthesis Techhnology Mathod of Aspartic acid In the Word

    Institute of Scientific and Technical Information of China (English)

    李冰; 李永祥

    2008-01-01

    天冬氨酸(Aspartic acid)是构成蛋白质的20种基本氨基酸之一,其在生化试剂和临床医学方面具有广泛的应用.它有两种旋光异构体:D型和L型.重点介绍了国内外天冬氮酸制备技术的12种路线和方法.

  6. Estimation of free energy barriers in the cytoplasmic and mitochondrial aspartate aminotransferase reactions probed by hydrogen-exchange kinetics of C alpha-labeled amino acids with solvent

    Energy Technology Data Exchange (ETDEWEB)

    Julin, D.A.; Wiesinger, H.; Toney, M.D.; Kirsch, J.F. (Univ. of California, Berkeley (USA))

    1989-05-02

    The existence of the postulated quinonoid intermediate in the cytoplasmic aspartate amino-transferase catalyzed transamination of aspartate to oxaloacetate was probed by determining the extent of transfer of tritium from the C alpha position of tritiated L-aspartate to pyridoxamine 5'-phosphate in single turnover experiments in which washout from the back-reaction was obviated by product trapping. The maximum amount of transferred tritium observed was 0.7%, consistent either with a mechanism in which a fraction of the net transamination reaction proceeds through a quinonoid intermediate or with a mechanism in which this intermediate is formed off the main reaction pathway. It is shown that transfer of labeled hydrogen from the amino acid to cofactor cannot be used to differentiate a stepwise from a concerted transamination mechanism. The amount of tritium transferred is a function of the rate constant for torsional equilibration about the epsilon-amino group of Lys-258, the presumptive abstractor of the C alpha proton; the relative rate constants for hydrogen exchange with solvent versus cofactor protonation; and the tritium isotope effect on this ratio. The free energy barriers facing the covalent intermediate between aldimine and keto acid product (i.e., ketimine and possibly quinonoid) were evaluated relatively by comparing the rates of C alpha-hydrogen exchange in starting amino acid with the rates of keto acid formation. The value of theta (= kexge/kprod) was found to be 2.6 for the reaction of cytoplasmic isozyme with aspartate and ca. 0.5 for that of the mitochondrial form with glutamate.

  7. HPLC法测定门冬氨酸钾镁注射液中门冬氨酸的含量%Determination of aspartic acid in potassium magnesium aspartate injection by HPLC

    Institute of Scientific and Technical Information of China (English)

    徐三能; 张静

    2014-01-01

    Objective To establish an HPLC method for determination of aspartic acid in potassium magnesium aspartate injection. Methods Inertsil ODS-SP column (5 μm,4.6 mm ×250 mm)was used.The mobile phase was acetonitrile-30 mmol·L-1 sodium dodecyl sulfate (plus 0.85 mL triethylamine,pH adjusted to 2.5 sing phosphoric acid)(150∶850)with a flow rate of 1.0 mL· min-1 .The detection wavelength was at 210nm,with the column temperature of 40℃.Results Aspartic acid had a good linear relation in the range of2.06~12.36 μg (r=0.999 8,n=6).The average recovery(n=6)was 99.72%,and RSD was 1.0%.Conclusions This method is simple,accurate,well stable,which can be used as an effective detection method of potassium magnesium injection.%目的:建立HPLC法测定门冬氨酸钾镁注射液中门冬氨酸的含量。方法采用Inertsil ODS-SP色谱柱(5μm,4.6 mm ×250 mm),流动相为乙腈-30 mmol·L-1十二烷基硫酸钠(加三乙胺0.85 mL,用磷酸调pH至2.5)(150∶850),流速为1.0 mL ·min-1,检测波长为210 nm,柱温为40℃。结果门冬氨酸在进样量为2.06~12.36μg范围内线性关系良好(r=0.9998,n=6),平均回收率为99.72%,RSD为1.0%。结论该方法操作简便、准确、稳定性好,可作为门冬氨酸钾镁注射液中门冬氨酸的有效检测方法。

  8. The Clinical Spectrum of Missense Mutations of the First Aspartic Acid of cbEGF-like Domains in Fibrillin-1 Including a Recessive Family

    Science.gov (United States)

    Hilhorst-Hofstee, Yvonne; Rijlaarsdam, Marry EB; Scholte, Arthur JHA; Swart-van den Berg, Marietta; Versteegh, Michel IM; van der Schoot-van Velzen, Iris; Schäbitz, Hans-Joachim; Bijlsma, Emilia K; Baars, Marieke J; Kerstjens-Frederikse, Wilhelmina S; Giltay, Jacques C; Hamel, Ben C; Breuning, Martijn H; Pals, Gerard

    2010-01-01

    Marfan syndrome (MFS) is a dominant disorder with a recognizable phenotype. In most patients with the classical phenotype mutations are found in the fibrillin-1 gene (FBN1) on chromosome 15q21. It is thought that most mutations act in a dominant negative way or through haploinsufficiency. In 9 index cases referred for MFS we detected heterozygous missense mutations in FBN1 predicted to substitute the first aspartic acid of different calcium-binding Epidermal Growth Factor-like (cbEGF) fibrillin-1 domains. A similar mutation was found in homozygous state in 3 cases in a large consanguineous family. Heterozygous carriers of this mutation had no major skeletal, cardiovascular or ophthalmological features of MFS. In the literature 14 other heterozygous missense mutations are described leading to the substitution of the first aspartic acid of a cbEGF domain and resulting in a Marfan phenotype. Our data show that the phenotypic effect of aspartic acid substitutions in the first position of a cbEGF domain can range from asymptomatic to a severe neonatal phenotype. The recessive nature with reduced expression of FBN1 in one of the families suggests a threshold model combined with a mild functional defect of this specific mutation. © 2010 Wiley-Liss, Inc. PMID:20886638

  9. Research progress on functional polymer poly (aspartic acid)%聚天冬氨酸功能高分子材料研究进展

    Institute of Scientific and Technical Information of China (English)

    余定华; 曹辉; 黄和

    2013-01-01

    首先概述了聚天冬氨酸广泛用于肥料增效剂等传统领域的最新进展,然后对聚天冬功能材料应用研究进行了综述,其中包括生物医学影像材料、智能凝胶材料、药物缓释材料、绿色分散剂以及燃料吸水剂等,最后对聚天冬氨酸功能材料未来的研究方向进行了评述.%Firstly,the application of poly(aspartic acid) used as fertilizer enhancer was reviewed. Then, the recent application of poly(aspartic acid) in biological imaging,smart hydrogel,drug delivery carrier, green dispersant,and water removal agents for fuel was described. Finally,the future research direction of the poly(aspartic acid) functional materials was proposed.

  10. Protection of Hydroxyl Groups as a Trimethylsilyl Ether by1,1,1,3,3,3-Hexamethyldisilazane Promoted by Aspartic Acid as an Efficient Organocatalyst%Protection of Hydroxyl Groups as a Trimethylsilyl Ether by 1,1,1,3,3,3-Hexamethyldisilazane Promoted by Aspartic Acid as an Efficient Organocatalyst

    Institute of Scientific and Technical Information of China (English)

    Arash GHORBANI-CHOGHAMARANI; Masoomeh NOROUZI

    2011-01-01

    A wide variety of alcohols and phenols were protected as trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyl disilazane catalyzed by aspartic acid as a non-toxic, metal-free, and green organocatalyst at room temperature in acetonitrile under mild and heterogeneous conditions. The procedure is operationally simple and the silylated product was obtained in high yield and purity.

  11. Improvement of post-thawed sperm quality and fertility of Arian rooster by oral administration of d-aspartic acid.

    Science.gov (United States)

    Ansari, Mahdi; Zhandi, Mahdi; Kohram, Hamid; Zaghari, Mojtaba; Sadeghi, Mostafa; Sharafi, Mohsen

    2017-04-01

    This study was conducted to investigate the effect of d-Aspartic acid (D-Asp) on post-thawed sperm quality, fertility and hatchability outcomes in male broiler breeders. Twenty 55-week-old roosters were selected and equally split into four groups (n = 5 rooster/group). Different daily D-Asp doses including 0 (D-0), 100 (D-100), 200 (D-200) or 300 (D-300) mg/kg BW were capsulated and individually administered for 12 weeks to roosters in each group. Semen samples were weekly collected from 7th to 12th week of experiment. Sperm quality from 7th to 11th week was evaluated in both fresh (total and forward motility and plasma membrane functionality) and post-thawed (total and forward motility, plasma membrane functionality, apoptosis status and mitochondrial activity) conditions. Also, collected semen samples on the 12th week were frozen and artificially inseminated to evaluate fertility and hatchability. The results from fresh condition showed that total and forward motility and plasma membrane functionality were significantly higher in D-200 compared to other groups. Also, interaction effect of time and treatment was not significant for all assessed parameters in fresh condition. In post-thawed condition, D-200 showed significantly higher total and forward motility, fertility and hatchability compared to other groups. The higher value for plasma membrane functionality and mitochondrial activity was observed in D-200 compared to D-0 and D300 groups. However, the percentage of live, early apoptotic and dead spermatozoa were not significantly affected by applied treatment in the current study. No significant difference for time and treat interaction effect was observed for all assessed parameters except forward motility. In conclusion, it seems that D-Asp administration could improve fresh and post-thawed sperm quality and post-thawed sperm fertility in male broiler breeders.

  12. Aspartic Acid Racemization and Collagen Degradation Markers Reveal an Accumulation of Damage in Tendon Collagen That Is Enhanced with Aging*

    Science.gov (United States)

    Thorpe, Chavaunne T.; Streeter, Ian; Pinchbeck, Gina L.; Goodship, Allen E.; Clegg, Peter D.; Birch, Helen L.

    2010-01-01

    Little is known about the rate at which protein turnover occurs in living tendon and whether the rate differs between tendons with different physiological roles. In this study, we have quantified the racemization of aspartic acid to calculate the age of the collagenous and non-collagenous components of the high strain injury-prone superficial digital flexor tendon (SDFT) and low strain rarely injured common digital extensor tendon (CDET) in a group of horses with a wide age range. In addition, the turnover of collagen was assessed indirectly by measuring the levels of collagen degradation markers (collagenase-generated neoepitope and cross-linked telopeptide of type I collagen). The fractional increase in d-Asp was similar (p = 0.7) in the SDFT (5.87 × 10−4/year) and CDET (5.82 × 10−4/year) tissue, and d/l-Asp ratios showed a good correlation with pentosidine levels. We calculated a mean (±S.E.) collagen half-life of 197.53 (±18.23) years for the SDFT, which increased significantly with horse age (p = 0.03) and was significantly (p < 0.001) higher than that for the CDET (34.03 (±3.39) years). Using similar calculations, the half-life of non-collagenous protein was 2.18 (±0.41) years in the SDFT and was significantly (p = 0.04) lower than the value of 3.51 (±0.51) years for the CDET. Collagen degradation markers were higher in the CDET and suggested an accumulation of partially degraded collagen within the matrix with aging in the SDFT. We propose that increased susceptibility to injury in older individuals results from an inability to remove partially degraded collagen from the matrix leading to reduced mechanical competence. PMID:20308077

  13. Factors affecting the formation of nitrogenous disinfection by-products during chlorination of aspartic acid in drinking water.

    Science.gov (United States)

    Chen, Wei; Liu, Zhigang; Tao, Hui; Xu, Hang; Gu, Yanmei; Chen, Zhaolin; Yu, Jingjing

    2017-01-01

    The formation of emerging nitrogenous disinfection by-products (N-DBPs) from the chlorination of aspartic acid (Asp) was investigated. The yield of dichloroacetonitrile (DCAN) was higher than other N-DBPs, such as dichloroacetamide(DCAcAm) and chloropicrin (TCNM) during the chlorination of Asp. The formation of DCAN, DCAcAm, and TCNM all showed a trend of first increasing and then decreasing during the chlorination of Asp with increasing contact time. The dosage of chlorine had an impact on the formation of DCAN, DCAcAm, and TCNM. The highest yields of DCAN and DCAcAm appeared when the Cl2/Asp molar ratio was about 20, the yield of TCNM increased with increasing the Cl2/Asp molar ratio from 5 to 30 and TCNM was not produced when the ratio was less than 5. Cyanogen chloride (CNCl) was detected when the Cl2/Asp molar ratio was lower than 5. N-DBPs formation was influenced by pH. DCAN formation increased with increasing pH from 5 to 6 and then decreased with increasing pH from 6 to 9, but DCAcAm and TCNM increased with increasing pH from 5 to 8 and then decreased. Higher temperatures reduced the formation of DCAN and DCAcAm, but increased TCNM formation. DCAN and DCAcAm formation decreased, and relatively stable TCNM formation increased, with increasing free chlorine contact time during chloramination. N-nitrosodimethylamine (NDMA) was produced during chloramination of Asp and increased with prolonged chloramination contact time. The presence of bromide ions enhanced the yields of haloacetonitriles and shifted N-DBPs to more brominated species.

  14. Adolescent social defeat alters N-methyl-D-aspartic acid receptor expression and impairs fear learning in adulthood.

    Science.gov (United States)

    Novick, Andrew M; Mears, Mackenzie; Forster, Gina L; Lei, Yanlin; Tejani-Butt, Shanaz M; Watt, Michael J

    2016-05-01

    Repeated social defeat of adolescent male rats results in adult mesocortical dopamine hypofunction, impaired working memory, and increased contextual anxiety-like behavior. Given the role of glutamate in dopamine regulation, cognition, and fear and anxiety, we investigated potential changes to N-methyl-D-aspartic acid (NMDA) receptors following adolescent social defeat. As both NMDA receptors and mesocortical dopamine are implicated in the expression and extinction of conditioned fear, a separate cohort of rats was challenged with a classical fear conditioning paradigm to investigate whether fear learning is altered by adolescent defeat. Quantitative autoradiography was used to measure 3H-MK-801 binding to NMDA receptors in regions of the medial prefrontal cortex, caudate putamen, nucleus accumbens, amygdala and hippocampus. Assessment of fear learning was achieved using an auditory fear conditioning paradigm, with freezing toward the auditory tone used as a measure of conditioned fear. Compared to controls, adolescent social defeat decreased adult NMDA receptor expression in the infralimbic region of the prefrontal cortex and central amygdala, while increasing expression in the CA3 region of the hippocampus. Previously defeated rats also displayed decreased conditioned freezing during the recall and first extinction periods, which may be related to the observed decreases and increases in NMDA receptors within the central amygdala and CA3, respectively. The alteration in NMDA receptors seen following adolescent social defeat suggests that dysfunction of glutamatergic systems, combined with mesocortical dopamine deficits, likely plays a role in the some of the long-term behavioral consequences of social stressors in adolescence seen in both preclinical and clinical studies.

  15. Aspartic acid-96 is the internal proton donor in the reprotonation of the Schiff base of bacteriorhodopsin.

    Science.gov (United States)

    Otto, H; Marti, T; Holz, M; Mogi, T; Lindau, M; Khorana, H G; Heyn, M P

    1989-01-01

    Above pH 8 the decay of the photocycle intermediate M of bacteriorhodopsin splits into two components: the usual millisecond pH-independent component and an additional slower component with a rate constant proportional to the molar concentration of H+, [H+]. In parallel, the charge translocation signal associated with the reprotonation of the Schiff base develops a similar slow component. These observations are explained by a two-step reprotonation mechanism. An internal donor first reprotonates the Schiff base in the decay of M to N and is then reprotonated from the cytoplasm in the N----O transition. The decay rate of N is proportional to [H+]. By postulating a back reaction from N to M, the M decay splits up into two components, with the slower one having the same pH dependence as the decay of N. Photocycle, photovoltage, and pH-indicator experiments with mutants in which aspartic acid-96 is replaced by asparagine or alanine, which we call D96N and D96A, suggest that Asp-96 is the internal proton donor involved in the re-uptake pathway. In both mutants the stoichiometry of proton pumping is the same as in wild type. However, the M decay is monophasic, with the logarithm of the decay time [log (tau)] linearly dependent on pH, suggesting that the internal donor is absent and that the Schiff base is directly reprotonated from the cytoplasm. Like H+, azide increases the M decay rate in D96N. The rate constant is proportional to the azide concentration and can become greater than 100 times greater than in wild type. Thus, azide functions as a mobile proton donor directly reprotonating the Schiff base in a bimolecular reaction. Both the proton and azide effects, which are absent in wild type, indicate that the internal donor is removed and that the reprotonation pathway is different from wild type in these mutants. PMID:2556706

  16. Cholinergic modulation of non-N-methyl-D-aspartic acid glutamatergic transmission in the chick ventral lateral geniculate nucleus.

    Science.gov (United States)

    Guo, J-Z; Sorenson, E M; Chiappinelli, V A

    2010-03-17

    Neurotransmission between glutamatergic terminals of retinal ganglion cells and principal neurons of the ventral lateral geniculate nucleus (LGNv) was examined with patch clamp recordings in chick brain slices during electrical stimulation of the optic tract. Since muscarinic and nicotinic receptors are present in high densities in LGNv, the present study examined possible roles of both receptors in modulating retinogeniculate transmission. During whole-cell recordings from LGNv neurons, acetylcholine (ACh, 100 microM) caused an initial increase in amplitudes of optic tract-evoked non-N-methyl-D-aspartic acid (NMDA) glutamatergic postsynaptic currents (PSCs). This increase was unchanged when 1 microM atropine was present, indicating that this initial enhancement of PSCs was due entirely to activation of nicotinic receptors. However, during washout of ACh the amplitudes of evoked PSCs became significantly decreased by 40.4+/-5.0% for several minutes before recovering to their original amplitudes, an effect blocked by 1 microM atropine. Exogenously applied muscarine (10 microM) markedly depressed optic tract-evoked PSCs, and this decrease in amplitude was blocked by atropine. In a second set of experiments, we examined effects of releasing endogenous ACh prior to optic tract stimulation. This was accomplished by stimulation of the lateral portion of LGNv via a separate conditioning electrode. Following a brief train of low intensity conditioning stimuli, non-NMDA glutamatergic PSCs evoked by optic tract stimulation were potentiated. However, at higher conditioning stimulus intensities the PSCs were markedly decreased compared with control, and this decrease was partially blocked by atropine (1 microM). Neither ACh nor muscarine altered amplitudes of PSCs elicited by exogenously applied glutamate. Muscarine significantly reduced the frequency but not the amplitudes of miniature PSCs, consistent with a presynaptic location for muscarinic receptors mediating these

  17. A Soluble, Folded Protein without Charged Amino Acid Residues

    DEFF Research Database (Denmark)

    Højgaard, Casper; Kofoed, Christian; Espersen, Roall;

    2016-01-01

    Charges are considered an integral part of protein structure and function, enhancing solubility and providing specificity in molecular interactions. We wished to investigate whether charged amino acids are indeed required for protein biogenesis and whether a protein completely free of titratable...... side chains can maintain solubility, stability, and function. As a model, we used a cellulose-binding domain from Cellulomonas fimi, which, among proteins of more than 100 amino acids, presently is the least charged in the Protein Data Bank, with a total of only four titratable residues. We find...

  18. Poly(ornithine-co-arginine-co-glycine-co-aspartic Acid): Preparation via NCA Polymerization and its Potential as a Polymeric Tumor-Penetrating Agent.

    Science.gov (United States)

    Yu, Haiyang; Tang, Zhaohui; Zhang, Dawei; Song, Wantong; Duan, Taicheng; Gu, Jingkai; Chen, Xuesi

    2015-06-01

    A novel random copolypeptide of ornithine, arginine, glycine, and aspartic acid [Poly(ornithine-co-arginine-co-glycine-co-aspartic acid), Poly(O,R,G,D)] has been prepared through ring-opening polymerization of N-δ-carbobenzoxy-l-ornithine N-carboxyanhydride [Orn(Cbz)-NCA)], l-glycine N-carboxyanhydride (Gly-NCA) and β-benzyl l-aspartate N-carboxyanhydride [Asp(Bn)-NCA], following by subsequent deprotection and guanidization. The structure of Poly(O,R,G,D) was confirmed by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). Low cytotoxicity of Poly(O,R,G,D) was confirmed from MTT assay. The Poly(O,R,G,D) contain some internal sequences of RXXR (X = O, R, G, or D) that could be proteolytically cleaved to expose the cryptic CendR element and bind to Neuropilin-1. This would lead to vascular and tissue permeabilization. Therefore trypsin-cleaved Poly(O,R,G,D) increase the vascular leakage of Evans blue from dermal microvessels at the injection site in vivo skin permeability assay. The intratumoral injection of the Poly(O,R,G,D) significantly enhanced the concentration of cisplatin-loaded nanoparticles in MCF-7 solid tumors. These results show that Poly(O,R,G,D) could increase the vascular leakage and tissue penetration of nanoparticles in a solid tumor and can be used as a potential polymeric tumor-penetrating agent.

  19. Structures of aspartic acid-96 in the L and N intermediates of bacteriorhodopsin: analysis by Fourier transform infrared spectroscopy

    Science.gov (United States)

    Maeda, A.; Sasaki, J.; Shichida, Y.; Yoshizawa, T.; Chang, M.; Ni, B.; Needleman, R.; Lanyi, J. K.

    1992-01-01

    The light-induced difference Fourier transform infrared spectrum between the L or N intermediate minus light-adapted bacteriorhodopsin (BR) was measured in order to examine the protonated states and the changes in the interactions of carboxylic acids of Asp-96 and Asp-115 in these intermediates. Vibrational bands due to the protonated and unprotonated carboxylic acid were identified by isotope shift and band depletion upon substitution of Asp-96 or -115 by asparagine. While the signal due to the deprotonation of Asp-96 was clearly observed in the N intermediate, this residue remained protonated in L. Asp-115 was partially deprotonated in L. The C = O stretching vibration of protonated Asp-96 of L showed almost no shift upon 2H2O substitution, in contrast to the corresponding band of Asp-96 or Asp-115 of BR, which shifted by 9-12 cm-1 under the same conditions. In the model system of acetic acid in organic solvents, such an absence of the shift of the C = O stretching vibration of the protonated carboxylic acid upon 2H2O substitution was seen only when the O-H of acetic acid is hydrogen-bonded. The non-hydrogen-bonded monomer showed the 2H2O-dependent shift. Thus, the O-H bond of Asp-96 enters into hydrogen bonding upon conversion of BR to L. Its increased hydrogen bonding in L is consistent with the observed downshift of the O-H stretching vibration of the carboxylic acid of Asp-96.

  20. Methodology for detecting residual phosphoric acid in polybenzoxazole fibers.

    Science.gov (United States)

    Park, Eun Su; Sieber, John; Guttman, Charles; Rice, Kirk; Flynn, Kathleen; Watson, Stephanie; Holmes, Gale

    2009-12-01

    Because of the premature failure of in-service soft-body armor containing the ballistic fiber poly[(benzo-[1,2-d:5,4-d']-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), the Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology (NIST) initiated a research program to investigate the reasons for this failure and to develop testing methodologies and protocols to ensure that these types of failures do not reoccur. In a report that focused on the stability of the benzoxazole ring that is characteristic of PBO fibers, Holmes, G. A.; Rice, K.; Snyder, C. R. J. Mater. Sci. 2006, 41, 4105-4116, showed that the benzoxazole ring was susceptible to hydrolytic degradation under acid conditions. Because of the processing conditions for the fibers, it is suspected by many researchers that residual phosphoric acid may cause degradation of the benzoxazole ring resulting in a reduction of ballistic performance. Prior to this work, no definitive data have indicated the presence of phosphoric acid since the residual phosphorus is not easily extracted and the processed fibers are known to incorporate phosphorus containing processing aids. Methods to efficiently extract phosphorus from PBO are described in this article. Further, characterization determined that the majority of the extractable phosphorus in PBO was attributed to the octyldecyl phosphate processing aid with some phosphoric acid being detected. Analysis by matrix assisted laser desorption ionization of model PBO oligomers indicates that the nonextractable phosphorus is attached to the PBO polymer chain as a monoaryl phosphate ester. The response of model aryl phosphates to NaOH exposure indicates that monoaryl phosphate ester is stable to NaOH washes used in the manufacturing process to neutralize the phosphoric acid reaction medium and to extract residual phosphorus impurities.

  1. Effects of L-glutamate/D-aspartate and monensin on lactic acid production in retina and cultured retinal Müller cells

    OpenAIRE

    Winkler, Barry S.; Sauer, Michael W.; Starnes, Catherine A.

    2004-01-01

    We have investigated the dependence of the rate of lactic acid production on the rate of Na+ entry in cultured transformed rat Müller cells and in normal and dystrophic (RCS) rat retinas that lack photoreceptors. To modulate the rate of Na+ entry, two approaches were employed: (i) the addition of L-glutamate (D-aspartate) to stimulate coupled uptake of Na+ and the amino acid; and (ii) the addition of monensin to enhance Na+ exchange. Müller cells produced lactate aerobically and anaerobically...

  2. N-(5′-Phosphopyridoxyl)glutamic acid and N-(5′-phosphopyridoxyl)-2-oxopyrrolidine-5-carboxylic acid and their action on the apoenzyme of aspartate aminotransferase

    Science.gov (United States)

    Khomutov, Radiǐ M.; Dixon, Henry B. F.; Vdovina, Lyudmila V.; Kirpichnikov, Mikhaǐl P.; Morozov, Yuriǐ V.; Severin, Evgeniǐ S.; Khurs, Elena N.

    1971-01-01

    1. N-(5′-Phosphopyridoxyl)-l-glutamic acid (P-Pxy-Glu, compound I) is readily converted at pH3 into a substance (P-Pxy-Glp, compound II) characterized as N-(5′-phosphopyridoxyl)-2-oxopyrrolidine-5-carboxylic acid. 2. The u.v., i.r. and fluorescence spectra of P-Pxy-Glu and P-Pxy-Glp have been determined; from the u.v. spectra their pK values have been found and compared. 3. The apoenzyme of aspartate aminotransferase is rapidly and irreversibly inactivated by P-Pxy-Glu, but is inactivated more slowly by P-Pxy-Glp. The complex with P-Pxy-Glp is stable enough to be isolated, but it is slowly reactivated in the presence of excess of pyridoxal phosphate. 4. The u.v. spectrum of the complex of apoenzyme and P-Pxy-Glp suggests that it contains a hydrogen bond between the phenolic hydroxyl group and the pyrrolidone nitrogen; this specifies the conformation of most of the molecule of P-Pxy-Glp. This conformation is similar to that previously postulated for the enzyme–glutamate complex except for the side chain of glutamate. Hence both the affinity of P-Pxy-Glp for the apoenzyme and the fact that it is more easily removed than P-Pxy-Glu are explicable. PMID:5126478

  3. Composite poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/collagen nanofibrous scaffolds for dermal tissue regeneration.

    Science.gov (United States)

    Ravichandran, Rajeswari; Venugopal, Jayarama Reddy; Sundarrajan, Subramanian; Mukherjee, Shayanti; Sridhar, Radhakrishnan; Ramakrishna, Seeram

    2012-08-01

    Tissue engineering scaffolds for skin tissue regeneration is an ever expounding area of research, as the products that meet the necessary requirements are far and elite. The nanofibrous poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/Collagen (PLLA/PAA/Col I&III) scaffolds were fabricated by electrospinning and characterized by SEM, contact angle and FTIR analysis for skin tissue regeneration. The cell-scaffold interactions were analyzed by cell proliferation and their morphology observed in SEM. The results showed that the cell proliferation was significantly increased (p≤0.05) in PLLA/PAA/Col I&III scaffolds compared to PLLA and PLLA/PAA nanofibrous scaffolds. The abundance and accessibility of adipose derived stem cells (ADSCs) may prove to be novel cell therapeutics for dermal tissue regeneration. The differentiation of ADSCs was confirmed using collagen expression and their morphology by CMFDA dye extrusion technique. The current study focuses on the application of PLLA/PAA/Col I&III nanofibrous scaffolds for skin tissue engineering and their potential use as substrate for the culture and differentiation of ADSCs. The objective for inclusion of a novel cell binding moiety like PAA was to replace damaged extracellular matrix and to guide new cells directly into the wound bed with enhanced proliferation and overall organization. This combinatorial epitome of PLLA/PAA/Col I&III nanofibrous scaffold with stem cell therapy to induce the necessary paracrine signalling effect would favour faster regeneration of the damaged skin tissues.

  4. Computational Investigation and Hydrogen/Deuterium Exchange of the Fixed Charge Derivative Tris(2,4,6-Trimethoxyphenyl)Phosphonium: Implications for the Aspartic Acid Cleavage Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, Kristin A.; Wysocki, Vicki H.; Vorpagel, Erich R.

    2005-05-25

    Aspartic acid (Asp)-containing peptides with the fixed charge derivative tris(2,4,6-trimethoxyphenyl) phosphonium (tTMP-P+) were explored computationally and experimentally by H/D exchange and fragmentation studies in order to probe the phenomenon of selective cleavage C-terminal to Asp in the absence of a ''mobile'' proton. Ab initio modeling of the tTMP-P+ electrostatic potential demonstrates the positive charge is distributed on the phosphonium group and therefore is not initiating or directing fragmentation as would a ''mobile'' proton. Geometry optimizations and vibrational analyses of different aspartic acid conformations show the aspartic acid structure with a hydrogen bond between the side chain hydroxy and backbone carbonyl lies 2.8 kcal/mol above the lowest energy conformer. In reactions with D2O, the phosphonium-derived doubly charged peptide (H+)P+LDIFSDF rapidly exchanges all 12 of its exchangeable hydrogens for deuterium and also displays a non-exchanging population. With no added proton, P+LDIFSDF exchanges a maximum of four of eleven exchangeable hydrogens for deuterium. No exchange is observed when all acidic groups are converted to the corresponding methyl esters. Together, these H/D exchange results indicate that the acidic hydrogens are ''mobile locally'' because they are able to participate in exchange even in the absence of an added proton. Fragmentation of two distinct (H+)P+LDIFSDF ion populations shows the non-exchanging population displays selective cleavage, while the exchanging population fragments more evenly across the peptide backbone. This result demonstrates that H/D exchange can sometimes distinguish between and provide a means of separation of different protonation motifs, and that these protonation motifs can have an effect on the fragmentation.

  5. Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

    Science.gov (United States)

    Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

    2016-09-01

    There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe3+/Fe2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles' formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH.

  6. N-Linked Glycosyl Auxiliary-Mediated Native Chemical Ligation on Aspartic Acid: Application towards N-Glycopeptide Synthesis.

    Science.gov (United States)

    Chai, Hua; Le Mai Hoang, Kim; Vu, Minh Duy; Pasunooti, Kalyan; Liu, Chuan-Fa; Liu, Xue-Wei

    2016-08-22

    A practical approach towards N-glycopeptide synthesis using an auxiliary-mediated dual native chemical ligation (NCL) has been developed. The first NCL connects an N-linked glycosyl auxiliary to the thioester side chain of an N-terminal aspartate oligopeptide. This intermediate undergoes a second NCL with a C-terminal thioester oligopeptide. Mild cleavage provides the desired N-glycopeptide.

  7. Crystal structure of Clostridium acetobutylicum Aspartate kinase (CaAK): An important allosteric enzyme for amino acids production.

    Science.gov (United States)

    Manjasetty, Babu A; Chance, Mark R; Burley, Stephen K; Panjikar, Santosh; Almo, Steven C

    2014-09-01

    Aspartate kinase (AK) is an enzyme which is tightly regulated through feedback control and responsible for the synthesis of 4-phospho-L-aspartate from L-aspartate. This intermediate step is at an important branch point where one path leads to the synthesis of lysine and the other to threonine, methionine and isoleucine. Concerted feedback inhibition of AK is mediated by threonine and lysine and varies between the species. The crystal structure of biotechnologically important Clostridium acetobutylicum aspartate kinase (CaAK; E.C. 2.7.2.4; Mw=48,030Da; 437aa; SwissProt: Q97MC0) has been determined to 3Å resolution. CaAK acquires a protein fold similar to the other known structures of AKs despite the low sequence identity (Clostridium tetani (64% sequence identity) suggesting the potential of the structure solved here to be applied for modeling drug interactions. CaAK structure may serve as a guide to better understand and engineer lysine biosynthesis for the biotechnology industry.

  8. Leukotriene A4 hydrolase: Selective abrogation of leukotriene B4 formation by mutation of aspartic acid 375

    Science.gov (United States)

    Rudberg, Peter C.; Tholander, Fredrik; Thunnissen, Marjolein M. G. M.; Samuelsson, Bengt; Haeggström, Jesper Z.

    2002-01-01

    Leukotriene A4 (LTA4, 5S-trans-5,6-oxido-7,9-trans-11,14-cis-eicosatetraenoic acid) hydrolase (LTA4H)/aminopeptidase is a bifunctional zinc metalloenzyme that catalyzes the final and rate-limiting step in the biosynthesis of leukotriene B4 (LTB4, 5S,12R-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid), a classical chemoattractant and immune modulating lipid mediator. Two chemical features are key to the bioactivity of LTB4, namely, the chirality of the 12R-hydroxyl group and the cis-trans-trans geometry of the conjugated triene structure. From the crystal structure of LTA4H, a hydrophilic patch composed of Gln-134, Tyr-267, and Asp-375 was identified in a narrow and otherwise hydrophobic pocket, believed to bind LTA4. In addition, Asp-375 belongs to peptide K21, a previously characterized 21-residue active site-peptide to which LTA4 binds during suicide inactivation. In the present report we used site-directed mutagenesis and x-ray crystallography to show that Asp-375, but none of the other candidate residues, is specifically required for the epoxide hydrolase activity of LTA4H. Thus, mutation of Asp-375 leads to a selective loss of the enzyme's ability to generate LTB4 whereas the aminopeptidase activity is preserved. We propose that Asp-375, possibly assisted by Gln-134, acts as a critical determinant for the stereoselective introduction of the 12R-hydroxyl group and thus the biological activity of LTB4. PMID:11917124

  9. Aspartate aminotransferase – key enzyme in the human systemic metabolism

    Directory of Open Access Journals (Sweden)

    Dagmara Otto-Ślusarczyk

    2016-03-01

    Full Text Available Aspartate aminotransferase is an organ - nonspecific enzyme located in many tissues of the human body where it catalyzes reversible reaction of transamination. There are two aspartate aminotransferase isoforms - cytoplasmic (AST1 and mitochondrial (AST2, that usually occur together and interact with each other metabolically. Both isoforms are homodimers containing highly conservative regions responsible for catalytic properties of enzyme. The common feature of all aspartate aminotransfeses is Lys – 259 residue covalent binding with prosthetic group - pyridoxal phosphate. The differences in the primary structure of AST isoforms determine their physico-chemical, kinetic and immunological properties. Because of the low concentration of L-aspartate (L-Asp in the blood, AST is the only enzyme, which supply of this amino acid as a substrate for many metabolic processes, such as urea cycle or purine and pyrimidine nucleotides in the liver, synthesis of L-arginine in the kidney and purine nucleotide cycle in the brain and the skeletal muscle. AST is also involved in D-aspartate production that regulates the metabolic activity at the auto-, para- and endocrine level. Aspartate aminotransferase is a part of the malate-aspartate shuttle in the myocardium, is involved in gluconeogenesis in the liver and kidney, glyceroneogenesis in the adipose tissue, and synthesis of neurotransmitters and neuro-glial pathway in the brain. Recently, the significant role of AST in glutaminolysis - normal metabolic pathway in tumor cells, was demonstrated. The article is devoted the role of AST, known primarily as a diagnostic liver enzyme, in metabolism of various human tissues and organs.

  10. Contributions of Individual Amino Acid Residues to the Endogenous CLV3 Function in Shoot Apical Meristem Maintenance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Xiu-Fen Song; Da-Li Yu; Ting-Ting Xu; Shi-Chao Ren; Peng Guo; Chun-Ming Liu

    2012-01-01

    As a peptide hormone,CLV3 restricts the stem cell number in shoot apical meristem (SAM) by interacting with CLV1/CLV2/CRN/RPK2 receptor complexes.To elucidate howthe function of the CLV3 peptide in SAM maintenance is established at the amino acid (AA) level,alanine substitutions were performed by introducing point mutations to individual residues in the peptide-coding region of CLV3 and its flanking sequences.Constructs carrying such substitutions,expressed under the control of CLV3 regulatory elements,were transformed to the clv3-2 null mutant to evaluate their efficiencies in complementing its defects in SAMs in vivo.These studies showed that aspartate-8,histidine-11,glycine-6,proline-4,arginine-1,and proline-9,arranged in an order of importance,were critical,while threonine-2,valine-3,serine-5,and the previously assigned hydroxylation and arabinosylation residue proline-7 were trivial for the endogenous CLV3 function in SAM maintenance.In contrast,substitutions of flanking residues did not impose much damage on CLV3.Complementation of different alanine-substituted constructs was confirmed by measurements of the sizes of SAMs and the WUS expression levels in transgenic plants.These studies established a complete contribution map of individual residues in the peptide-coding region of CLV3 for its function in SAM,which may help to understand peptide hormones in general.

  11. Detection of Serine Octamer by Desorption Electrospray Ionization Mass Spectrometry in Resultant Mixture of Aspartic Acid Exposed to Sunshine Under Natural Conditions

    Institute of Scientific and Technical Information of China (English)

    CHEN Huan-wen; LI Ming; JIN Wei; JIN Qin-han; ZHENG Jian

    2007-01-01

    Serine, one of the nonessential amino acids, is of principal interest because of its capability to form magic-number ionic clusters, which provide a remarkable preference for homochirality. With L-aspartic acid as the precursor,this study provides experimental evidence for serine formation in weak acidified aqueous solutions in the presence of iron, with exposure to sunlight, which simulates the natural conditions of the prebiotic aqueous environment. The resultant mixture is directly analyzed via desorption electrospray ionization mass spectrometry( DESI-MS), without any sample preseparation. The serine monomer is successfully detected as protonated molecules, giving a peak at m/z 106, which is confirmed by the MS/MS fragments. Protonated serine octamer(m/z 841) is also observed with significant abundance in the MS spectra and is confirmed by the MS/MS data, which shows the formation of the serine octamer by a synthesized serine in the resultant mixture. It is also found that the serine octamer yielded equivalent abundance in the DESI mass spectra in a wide pH range(pH=1-5), and that existence of ferrous salt and sunshine are essential for the conversion of aspartic acid to serine in the acidic water solution.

  12. Solubilities of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid in water

    Energy Technology Data Exchange (ETDEWEB)

    Mishelevich, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel); Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel)], E-mail: apelblat@bgu.ac.il

    2008-05-15

    The solubility in water of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid was determined in the 278.15 K to 343.15 K temperature range. The solubility of these compounds served to permit the evaluation of the apparent molar enthalpies of solution.

  13. Reduction in crystal symmetry of a solid solution: A neutron diffraction study at 15 K of the host/guest system asparagine/aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Weisinger-Lewin, Y.; Frolow, F.; Lahav, M.; Leiserowitz, L. (Weizmann Institute of Science, Rehovot (Israel)); McMullan, R.K.; Koetzle, T.F. (Brookhaven National Lab., Upton, NY (USA))

    1989-02-01

    It has been demonstrated, for the first time by diffraction methods, that a solid solution composed of host and guest molecules can exhibit a crystal symmetry lower than that of the host. The study proves that the symmetry of a solid solution is dependent not only upon the host crystal structure and the guest molecular structure but also upon the surface structure and symmetry of the host crystal. The crystal structures of (S)-asparagine monohydrate (D{sub 2}NCOCH{sub 2}CH(ND{sub 3})CO{sub 2} {times} D{sub 2}O) and of the solid solution (0.848:0.152) (S)-asparagine/(S)-aspartic acid (DO{sub 2}CCD{sub 2}CD(ND{sub 3})CO{sub 2}) monohydrate were refined by using neutron diffraction data obtained at 15 K. The space group of the pure host crystal is P2{sub 1}2{sub 1}2{sub 1} (Z = 4), whereas that of the host/guest crystal is monoclinic P12{sub 1}1 with two molecular sites per asymmetric unit. The ratios of guest/host occupancies of the two independent sites are 0.173:0.827 and 0.132:0.868. The reduction in symmetry is in accordance with the preferred adsorption of guest aspartic acid on the (010) crystal face at half of the orthorhombic, symmetry-related surface sites. Aspartic acid mimics, at the preferred (010) surface sites, molecular asparagine, participating in all hydrogen bonds. At the less-favored (010) surface sites a normal N-H{hor ellipsis}O(host) hydrogen bond is replaced by O(hydroxyl){hor ellipsis}O(host) repulsion between lone-pair electrons. 21 refs., 5 figs., 6 tabs.

  14. Electrocatalytic oxidation and determination of dopamine at a carbon ionic liquid electrode modified with nafion-L-aspartic acid composite film

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The electrocatalytic oxidation of dopamine(DA)was studied by electrochemical approaches at a carbon ionic liquid electrode(CILE)modified with the composite film of nafion and L-aspartic acid(NL-CILE).The CILE was fabricated by replacing non-conductive organic binders with a room-temperature hydrophobic ionic liquid,1-butyl-3-methyl-imidazolium hexafluorophosphate.The composite film of NL was used as matrix to adsorb DA and catalyze the oxidation of DA in phosphate buffer solution(PBS).The electrochemical re...

  15. Synthesis, Characterization and Antibacterial Properties of Rare Earth (Ce3+, Pr3+, Nd3+, Sm3+, Er3+)Complexes with L-Aspartic Acid and o-Phenanthroline

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Five novel ternary complexes of rare earth ions with L-Aspartic acid (Asp) and o-phenanthroline (Phen) were synthesized in ethanol aqueous solution. Their compositions were characterized by elemental analysis, molar conductance, FT-IR, Raman, UV-VIS and TG-DTA. The compositions of the complexes were confirmed to be: RE(Asp)3PhenCl3·3H2O (RE: Ce3+, Pr3+, Nd3+, Sm3+, Er3+). The antibacterial activity test shows that all these complexes exhibit excellent antibacterial ability against Escherichia coli, Staphylococcus aureus and Candida albicans. The antimicrobial spectrum of the complexes are broad.

  16. [Present possibilities of age determination in forensic medicine with emphasis on the importance of measurement of D- and L- forms of aspartic acid. I. An overview].

    Science.gov (United States)

    Pilin, A; Pudil, F; Gross, R; Herrmannová, M

    1997-02-01

    Evaluation of age of unknown deceased persons belongs to the most important ways to identification. For the time being, morphological methods are used, namely evaluation of age according to Gustafson's method from tooth grindings or by macroscopical estimation of abrasion, transparency of root dentine, alveolar atrophy and number of missing teeth. Evaluation of the data can be influenced by an individual failure and experience showed an age related decrease of precision. Recently, some papers occurred estimating a relation of D, L-forms of aspartic acid which depends on the age with a significant precision.

  17. Crystal structure of Clostridium acetobutylicum aspartate kinase (CaAk: An important allosteric enzyme for amino acids production

    Directory of Open Access Journals (Sweden)

    Babu A. Manjasetty

    2014-09-01

    Full Text Available Aspartate kinase (AK is an enzyme which is tightly regulated through feedback control and responsible for the synthesis of 4-phospho-l-aspartate from l-aspartate. This intermediate step is at an important branch point where one path leads to the synthesis of lysine and the other to threonine, methionine and isoleucine. Concerted feedback inhibition of AK is mediated by threonine and lysine and varies between the species. The crystal structure of biotechnologically important Clostridium acetobutylicum aspartate kinase (CaAK; E.C. 2.7.2.4; Mw = 48,030 Da; 437aa; SwissProt: Q97MC0 has been determined to 3 Å resolution. CaAK acquires a protein fold similar to the other known structures of AKs despite the low sequence identity (<30%. It is composed of two domains: an N-terminal catalytic domain (kinase domain and a C-terminal regulatory domain further comprised of two small domains belonging to the ACT domain family. Pairwise comparison of 12 molecules in the asymmetric unit helped to identify the bending regions which are in the vicinity of ATP binding site involved in domain movements between the catalytic and regulatory domains. All 12 CaAK molecules adopt fully open T-state conformation leading to the formation of three tetramers unique among other similar AK structures. On the basis of comparative structural analysis, we discuss tetramer formation based on the large conformational changes in the catalytic domain associated with the lysine binding at the regulatory domains. The structure described herein is homologous to a target in wide-spread pathogenic (toxin producing bacteria such as Clostridium tetani (64% sequence identity suggesting the potential of the structure solved here to be applied for modeling drug interactions. CaAK structure may serve as a guide to better understand and engineer lysine biosynthesis for the biotechnology industry.

  18. Aspartate-444 is essential for productive substrate interactions in a neuronal glutamate transporter.

    Science.gov (United States)

    Teichman, Shlomit; Kanner, Baruch I

    2007-06-01

    In the central nervous system, electrogenic sodium- and potassium-coupled glutamate transporters terminate the synaptic actions of this neurotransmitter. In contrast to acidic amino acids, dicarboxylic acids are not recognized by glutamate transporters, but the related bacterial DctA transporters are capable of transporting succinate and other dicarboxylic acids. Transmembrane domain 8 contains several residues that differ between these two types of transporters. One of these, aspartate-444 of the neuronal glutamate transporter EAAC1, is conserved in glutamate transporters, but a serine residue occupies this position in DctA transporters. When aspartate-444 is mutated to serine, cysteine, alanine, or even to glutamate, uptake of D-[(3)H]-aspartate as well as the inwardly rectifying steady-state currents induced by acidic amino acids is impaired. Even though succinate was not capable of inducing any steady-state transport currents, the dicarboxylic acid inhibited the sodium-dependent transient currents by the mutants with a neutral substitution at position 444. In the neutral substitution mutants inhibition of the transients was also observed with acidic amino acids. In the D444E mutant, acidic amino acids were potent inhibitors of the transient currents, whereas the apparent affinity for succinate was lower by at least three orders of magnitude. Even though L-aspartate could bind to D444E with a high apparent affinity, this binding resulted in inhibition rather than stimulation of the uncoupled anion conductance. Thus, a carboxylic acid-containing side chain at position 444 prevents the interaction of glutamate transporters with succinate, and the presence of aspartate itself at this position is crucial for productive substrate binding compatible with substrate translocation.

  19. The First Aspartic Acid of the DQxD Motif for Human UDP-Glucuronosyltransferase 1A10 Interacts with UDP-Glucuronic Acid during Catalysis

    Science.gov (United States)

    Xiong, Yan; Patana, Anne-Sisko; Miley, Michael J.; Zielinska, Agnieszka K.; Bratton, Stacie M.; Miller, Grover P.; Goldman, Adrian; Finel, Moshe; Redinbo, Matt R.; Radominska-Pandya, Anna

    2008-01-01

    All UDP-glucuronosyltransferase enzymes (UGTs) share a common cofactor, UDP-glucuronic acid (UDP-GlcUA). The binding site for UDP-GlcUA is localized to the C-terminal domain of UGTs on the basis of amino acid sequence homology analysis and crystal structures of glycosyltransferases, including the C-terminal domain of human UGT2B7. We hypothesized that the 393DQMD-NAK399 region of human UGT1A10 interacts with the glucuronic acid moiety of UDP-GlcUA. Using site-directed mutagenesis and enzymatic analysis, we demonstrated that the D393A mutation abolished the glucuronidation activity of UGT1A10 toward all substrates. The effects of the alanine mutation at Q394, D396, and K399 on glucuronidation activities were substrate-dependent. Previously, we examined the importance of these residues in UGT2B7. Although D393 (D398 in UGT2B7) is similarly critical for UDP-GlcUA binding in both enzymes, the effects of Q394 (Q399 in UGT2B7) to Ala mutation on activity were significant but different between UGT1A10 and UGT2B7. A model of the UDP-GlcUA binding site suggests that the contribution of other residues to cosubstrate binding may explain these differences between UGT1A10 and UGT2B7. We thus postulate that D393 is critical for the binding of glucuronic acid and that proximal residues, e.g., Q394 (Q399 in UGT2B7), play a subtle role in cosubstrate binding in UGT1A10 and UGT2B7. Hence, this study provides important new information needed for the identification and understanding of the binding sites of UGTs, a major step forward in elucidating their molecular mechanism. PMID:18048489

  20. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid/Poly(vinyl alcohol IPN Hydrogel and Its Drug Controlled Release

    Directory of Open Access Journals (Sweden)

    Jingqiong Lu

    2015-01-01

    Full Text Available Modified poly(aspartic acid/poly(vinyl alcohol interpenetrating polymer network (KPAsp/PVA IPN hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid grafting 3-aminopropyltriethoxysilane (KH-550 and poly(vinyl alcohol (PVA as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM. The thermal stability was analyzed by thermogravimetric analysis (TGA. The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN, and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid and 62.5 wt% at pH = 7.4 (simulated intestinal fluid, respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery.

  1. Production of L-aspartic acid by bioreactors using immobilized microorganisms. Koteika biseibutsu wo mochiiru baio riakuta ni yoru L-asuparagin san no seizo

    Energy Technology Data Exchange (ETDEWEB)

    Sato, T. (Tanabe Seiyaku Co. Ltd., Osaka (Japan))

    1994-01-05

    A developmental progress of a continuous process is introduced, wherein L-aspartic acid is produced in an industrial scale from fumaric acid with immobilized aspartase. First, immobilization of aspartase extracted from Escherichia coli was tried by entrapping it in polyacryllamide gel. The enzyme was proved unstable to be used in an industrial scale because of being taken out of bacterial organism. It was found that E. coli with 10-fold high enzymic activity can be held by entrapping the bacteria in polyacrylamide gel without extracting enzyme. In consideration of optimum temperature, pH, heat resistance and other properties of E. coli, and of exothermic reaction, a continuous enzyme reactor was designed of a radiation (heat exchanger) type with E. coli packed multi-step columns. Using this reactor, the production cost of L-aspartic acid could be reduced to about 60 % of that by conventional batch-wise type. Further, the productivity has been raised remarkably by improving immobilizing efficiency with use of [kappa]-carrageenan instead of polyacrylamide and by using mutant strains with 7-fold high aspartase activity. 10 refs., 3 figs., 2 tabs.

  2. Possible modulation of N-methyl-D,L-aspartic acid induced prolactin release by testicular steroids in the adult male rhesus monkey

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, M.; Rizvi, S.S.R.; Jahan, S.; Zaidi, P.; Shahab, M. (Quaid-i-Azam Univ., Islamabad (Pakistan))

    1991-01-01

    N-methyl-D,L-aspartic acid (NMA), an agonist of the neurotransmitter glutamate has been shown to acutely stimulate the release of prolactin (PRL) in intact rats and monkeys. To further investigate the role of neuroexcitatory amino acids in PRL secretion, the effects of NMA administration were examined on PRL release in long term orchidectomized adult rhesus monkeys, in both the absence and presence of testosterone. Intact and long term castrated adult male monkeys weighing between 8-13 kg, were implanted with a catheter via the saphenous vein for blood withdrawal and drug infusion. Blood samples were collected at 10 min intervals for 50 min before and 70 min after administration of the drug or vehicle. Plasma PRL concentrations were estimated using radioimmunoassay. Whereas a single iv injection of NMA induced a prompt discharge of PRL in intact monkeys, an identical dose had surprisingly no effect on PRL secretion in orchidectomized animals. On the other hand, plasma PRL increases in response to a challenge dose of thyrotropin releasing hormone were similar in magnitude in the two groups of monkeys. Testosterone replacement in orchidectomized animals by parenteral administration of testosterone enanthate reinitiated the PRL responsiveness to acute NMA stimulation. These results indicate that N-methyl-D-aspartic acid (NMDA) dependent drive to PRL release in the adult male rhesus monkey may be overtly influenced by the sex steroid milieu.

  3. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release.

    Science.gov (United States)

    Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

    2015-01-01

    Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery.

  4. Composite poly-L-lactic acid/poly-({alpha},{beta})-DL-aspartic acid/collagen nanofibrous scaffolds for dermal tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Ravichandran, Rajeswari [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Venugopal, Jayarama Reddy, E-mail: nnijrv@nus.edu.sg [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Sundarrajan, Subramanian [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Mukherjee, Shayanti [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Sridhar, Radhakrishnan [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Ramakrishna, Seeram, E-mail: seeram@nus.edu.sg [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore)

    2012-08-01

    Tissue engineering scaffolds for skin tissue regeneration is an ever expounding area of research, as the products that meet the necessary requirements are far and elite. The nanofibrous poly-L-lactic acid/poly-({alpha},{beta})-DL-aspartic acid/Collagen (PLLA/PAA/Col I and III) scaffolds were fabricated by electrospinning and characterized by SEM, contact angle and FTIR analysis for skin tissue regeneration. The cell-scaffold interactions were analyzed by cell proliferation and their morphology observed in SEM. The results showed that the cell proliferation was significantly increased (p {<=} 0.05) in PLLA/PAA/Col I and III scaffolds compared to PLLA and PLLA/PAA nanofibrous scaffolds. The abundance and accessibility of adipose derived stem cells (ADSCs) may prove to be novel cell therapeutics for dermal tissue regeneration. The differentiation of ADSCs was confirmed using collagen expression and their morphology by CMFDA dye extrusion technique. The current study focuses on the application of PLLA/PAA/Col I and III nanofibrous scaffolds for skin tissue engineering and their potential use as substrate for the culture and differentiation of ADSCs. The objective for inclusion of a novel cell binding moiety like PAA was to replace damaged extracellular matrix and to guide new cells directly into the wound bed with enhanced proliferation and overall organization. This combinatorial epitome of PLLA/PAA/Col I and III nanofibrous scaffold with stem cell therapy to induce the necessary paracrine signalling effect would favour faster regeneration of the damaged skin tissues. - Highlights: Black-Right-Pointing-Pointer Differentiation of adipose derived stem cells in the presence of bFGF for wound healing Black-Right-Pointing-Pointer Introduction of PAA as ECM mimetic cell binding moiety Black-Right-Pointing-Pointer Combination of PLLA/PAA/Col I and III nanofibers and stem cell therapy for skin regeneration.

  5. Removal of coagulant aluminum from water treatment residuals by acid.

    Science.gov (United States)

    Okuda, Tetsuji; Nishijima, Wataru; Sugimoto, Mayo; Saka, Naoyuki; Nakai, Satoshi; Tanabe, Kazuyasu; Ito, Junki; Takenaka, Kenji; Okada, Mitsumasa

    2014-09-01

    Sediment sludge during coagulation and sedimentation in drinking water treatment is called "water treatment residuals (WTR)". Polyaluminum chloride (PAC) is mainly used as a coagulant in Japan. The recycling of WTR has been desired; one method for its reuse is as plowed soil. However, WTR reuse in this way is inhibited by the aluminum from the added PAC, because of its high adsorption capacity for phosphate and other fertilizer components. The removal of such aluminum from WTR would therefore be advantageous for its reuse as plowed soil; this research clarified the effect of acid washing on aluminum removal from WTR and on plant growth in the treated soil. The percentage of aluminum removal from raw WTR by sulphuric acid solution was around 90% at pH 3, the percentage decreasing to 40% in the case of a sun-dried sample. The maximum phosphate adsorption capacity was decreased and the available phosphorus was increased by acid washing, with 90% of aluminum removal. The enhancement of Japanese mustard spinach growth and the increased in plant uptake of phosphates following acid washing were observed.

  6. The role for an invariant aspartic acid in hypoxanthine phosphoribosyltransferases is examined using saturation mutagenesis, functional analysis, and X-ray crystallography.

    Science.gov (United States)

    Canyuk, B; Focia, P J; Eakin, A E

    2001-03-01

    The role of an invariant aspartic acid (Asp137) in hypoxanthine phosphoribosyltransferases (HPRTs) was examined by site-directed and saturation mutagenesis, functional analysis, and X-ray crystallography using the HPRT from Trypanosoma cruzi. Alanine substitution (D137A) resulted in a 30-fold decrease of k(cat), suggesting that Asp137 participates in catalysis. Saturation mutagenesis was used to generate a library of mutant HPRTs with random substitutions at position 137, and active enzymes were identified by complementation of a bacterial purine auxotroph. Functional analyses of the mutants, including determination of steady-state kinetic parameters and pH-rate dependence, indicate that glutamic acid or glutamine can replace the wild-type aspartate. However, the catalytic efficiency and pH-rate profile for the structural isosteric mutant, D137N, were similar to the D137A mutant. Crystal structures of four of the mutant enzymes were determined in ternary complex with substrate ligands. Structures of the D137E and D137Q mutants reveal potential hydrogen bonds, utilizing several bound water molecules in addition to protein atoms, that position these side chains within hydrogen bond distance of the bound purine analogue, similar in position to the aspartate in the wild-type structure. The crystal structure of the D137N mutant demonstrates that the Asn137 side chain does not form interactions with the purine substrate but instead forms novel interactions that cause the side chain to adopt a nonfunctional rotamer. The results from these structural and functional analyses demonstrate that HPRTs do not require a general base at position 137 for catalysis. Instead, hydrogen bonding sufficiently stabilizes the developing partial positive charge at the N7-atom of the purine substrate in the transition-state to promote catalysis.

  7. Total dietary fiber determined as neutral sugar residues, uronic acid residues, and Klason lignin (the Uppsala method): collaborative study.

    Science.gov (United States)

    Theander, O; Aman, P; Westerlund, E; Andersson, R; Pettersson, D

    1995-01-01

    A joint AOAC/American Association of Cereal Chemists (AACC) collaborative study was conducted to determine by the Uppsala method the dietary fiber content and its composition in various foods. The method includes preparation of a residue by treatment with thermostable alpha-amylase and amyloglucosidase and then ethanol precipitation of solubilized dietary fiber components while leaving low-molecular weight carbohydrates in solution. After acid hydrolysis of residue, neutral polysaccharide residues are determined as alditol acetates by gas-liquid chromatography, uronic acid residues are determined by colorimetry, and ash-free acid-insoluble residue (Klason lignin) is determined gravimetrically. Total dietary fiber, including enzyme-resistant starch, is calculated as the sum of nonstarch polysaccharide residues and Klason lignin. Nine laboratories completed the study, analyzing in duplicate 8 unknown dried products that included 4 cereal products, green peas, potato fiber, carrots, and apples. Total dietary fiber contents of products tested ranged from 4.6 to 84.3%, with an average RSDR value of 8.4% (range, 4.8-11.1%). Total neutral polysaccharide residues ranged from 3.8 to 64.1%, with an average RSDR value of 7.5% (range, 5.4-10.5%). Individual neutral sugars (rhamnose, arabinose, xylose, mannose, galactose, and glucose) and uronic acid residues present at more than 1% generally had good RSDR values (3.3-22.8%), whereas, as expected for Klason lignin, only the wheat bran sample with a high content (16%) had an excellent RSDR value (5.0%). The gas chromatographic-colorimetric-gravimetric method (Uppsala method) for determination of total dietary fiber (as neutral sugar residues, uronic acid residues, and Klason lignin) has been adopted first action by AOAC INTERNATIONAL.

  8. Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

    Science.gov (United States)

    Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali

    2017-02-01

    A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

  9. 聚天冬氨酸阻垢剂的制备及性能评价%Preparation and Performance Evaluation of Poly-aspartic Acid Scale Inhibitor

    Institute of Scientific and Technical Information of China (English)

    杨红丽; 姬彩云

    2015-01-01

    Poly-aspartic acid has good scale inhibition effect. Using maleic anhydride and ammonium chloride, poly-aspartic acid was prepared by hot-polymerization. And the optimum reaction conditions were obtained by or-thogonal experiment as follows:molar ratio of maleic anhydride/ammonium chloride was 1∶1. 2,reaction teampra-ture was 140℃,and reaction time was 5h.%聚天冬氨酸具有较好的阻垢效果。采用热引发聚合,以马来酸酐、氯化铵为原料,制备了绿色阻垢剂聚天冬氨酸,通过正交实验确定了最佳合成条件,并对其进行了性能评价。最佳合成条件为:马来酸酐和氯化铵的摩尔比为1∶1.2,反应温度为140℃,反应时间为5 h。

  10. Corticosterone, cortisol, triglycerides, aspartate aminotransferase and uric acid plasma concentrations during foie gras production in male mule ducks (Anas platyrhynchos × Cairina moschata).

    Science.gov (United States)

    Flament, A; Delleur, V; Poulipoulis, A; Marlier, D

    2012-01-01

    1. Corticosterone, cortisol, triglycerides, aspartate aminotransferase (AST) and uric acid (UA) plasma concentration were measured at 8 (7 days after group housing), 12 (after 7 days of force feeding) and 13 weeks of age (at slaughter after 12 days of force feeding), and 45 min after an adrenocorticotrophic hormone (ACTH) stimulation test at 8 weeks of age in 12 male mule ducks in an on-farm experiment. 2. No significant increase of corticosterone was found during the force-feeding period compared with the concentration after housing. 3. Comparison of corticosterone and cortisol values indicates that cortisol can be considered as a reliable acute stress indicator in future routine examinations. 4. Plasma concentrations of triglycerides and aspartate aminotransferase increased progressively from pre-force feeding period to slaughtering. 5. Plasma concentrations of uric acid increased from the start at 8 weeks of age to the mid-force feeding period but no difference was noticed between the mid-force feeding period and slaughtering. 6. It is concluded that acute stress induced by force-feeding is similar at the beginning and end of the commercial production of foie gras.

  11. Synthesis and characterization of aspartic acid-capped CdS/ZnS quantum dots in reverse micelles and its application to Hg(II) determination

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Mohammad Saeid, E-mail: mshosseini1336@yahoo.com; Kamali, Mohsen

    2015-11-15

    In this work, CdS/ZnS quantum dots (QDs) coated with aspartic acid (AsA) were synthesized in reverse micelles. The synthesized QDs were characterized by XRD, TEM, IR and photoluminescence (PL) spectroscopy. It was found that the intensity of CdS/ZnS QDs coated with AsA is much greater than CdS, and CdS/ZnS QDs. The interaction of some heavy metal ions with CdS/ZnS/AsA QDs was investigated at different buffering pH media. Based on the PL quenching of the QDs in the presence of each one of the metal ions, the feasibility of their determinations was examined according to the Stern–Volmer equation. The investigations showed that Hg(II) ions can be easily determined in contaminated atmospheric environments with the detection limit of 0.05 mg m{sup −3}. The results were satisfactorily confirmed by cold vapor atomic absorption spectrometric method. - Highlights: • A new CdS/ZnS quantum dot capped with aspartic acid (DDBA) was prepared. • The prepared QDs benefit from a favorable fluorescence. • Interaction of some metal ions with the QDs was examined according to the Stern–Volmer equation. • The determination of Hg(II) is feasible in the present of many co-existence metal ions. • The method benefits from a high-speed and considerable simplicity for Hg(II) determination.

  12. Role of lysine and acidic amino acid residues on the insecticidal activity of Jackbean urease.

    Science.gov (United States)

    Real-Guerra, Rafael; Carlini, Célia Regina; Stanisçuaski, Fernanda

    2013-09-01

    Canavalia ensiformis has three isoforms of urease: Jackbean urease (JBU), Jackbean urease II and canatoxin. These isoforms present several biological activities, independent from the enzymatic property, such as entomotoxicity and antifungal properties. The entomotoxic activity is a property of the whole protein, as well as of a 10 kDa peptide released by insect digestive enzymes. Here we have used chemical modification to observe the influence of lysines and acidic residues on JBU enzymatic and insecticidal activities. Chemical modification of lysine residues was performed with dimethylamine-borane complex and formaldehyde, and acidic residues were modified by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and ethylenediamine. Derivatized ureases, called JBU-Lys (lysine-modified) and JBU-Ac (acidic residues-modified), were assayed for their biochemical and insecticidal properties. Neither modification altered significantly the kinetic parameters analyzed, indicating that no residue critical for the enzyme activity was affected and that the modifications did not incur in any significant structural alteration. On the other hand, both modifications reduced the toxic activity of the native protein fed to Dysdercus peruvianus. The changes observed in the entomotoxic property of the derivatized proteins reflect alterations in different steps of JBU's toxicity towards insects. JBU-Ac is not susceptible to hydrolysis by insect digestive enzymes, hence impairing the release of toxic peptide(s), while JBU-Lys is processed as the native protein. On the other hand, the antidiuretic effect of JBU on Rhodnius prolixus is altered in JBU-Lys, but not in JBU-Ac. Altogether, these data emphasize the role of lysine and acidic residues on the insecticidal properties of ureases.

  13. Effect of propofol on the reactivity of acetylcholinesterase, N-methyl-D-aspartate receptors, and gamma-aminobutyric acid receptors in the hippocampus of aged rats after chronic cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    Gang Chen; Jiangbei Cao; Weidong Mi

    2011-01-01

    We induced ischemic brain injury in aging rats to examine the effects of varying doses of propofol on hippocampal activities of acetylcholinesterase, N-methyl-D-aspartate receptors, and γ-aminobutyric acid receptors. Propofol exhibited no obvious impact on acetylcholinesterase activity, but directly activated the γ-aminobutyric acid receptor. The neuroprotective function of propofol on the hippocampus of aging rats following cerebral ischemic injury may be related to altered activities of γ-aminobutyric acid receptors and N-methyl-D-aspartate receptors.

  14. 苯丙氨酸和天冬氨酸水溶液的纳滤分离过程研究%The Nanofiltration Process of Aqueous Solution of Phenylalanine and Aspartic Acid

    Institute of Scientific and Technical Information of China (English)

    营爱玲; 王晓琳

    2001-01-01

    The permeation experiments on the aqueous solution of phenylalanine and aspartic acid were carried out with nanofiltration membranes. Results show that amino acids with different isoelectric points (pI) can be separated satisfactorily by adjusting the pH values. The concentration and separation process of phenylalanine and aspartic acid solution was also simulated.%选择L-苯丙氨酸和L-天冬氨酸水溶液进行了纳滤分离过程研究,讨论了不同pH下氨基酸的透过特性,并进行了模拟计算.

  15. The Nature of Intermolecular Interactions Between Aromatic Amino Acid Residues

    Energy Technology Data Exchange (ETDEWEB)

    Gervasio, Francesco; Chelli, Riccardo; Procacci, Piero; Schettino, Vincenzo

    2002-05-01

    The nature of intermolecular interactions between aromatic amino acid residues has been investigated by a combination of molecular dynamics and ab initio methods. The potential energy surface of various interacting pairs, including tryptophan, phenilalanine, and tyrosine, was scanned for determining all the relevant local minima by a combined molecular dynamics and conjugate gradient methodology with the AMBER force field. For each of these minima, single-point correlated ab initio calculations of the binding energy were performed. The agreement between empirical force field and ab initio binding energies of the minimum energy structures is excellent. Aromatic-aromatic interactions can be rationalized on the basis of electrostatic and van der Waals interactions, whereas charge transfer or polarization phenomena are small for all intermolecular complexes and, particularly, for stacked structures.

  16. Proteomic Investigation of Protein Profile Changes and Amino Acid Residue Level Modification in Cooked Lamb Meat: The Effect of Boiling.

    Science.gov (United States)

    Yu, Tzer-Yang; Morton, James D; Clerens, Stefan; Dyer, Jolon M

    2015-10-21

    Hydrothermal treatment (heating in water) is a common method of general food processing and preparation. For red-meat-based foods, boiling is common; however, how the molecular level effects of this treatment correlate to the overall food properties is not yet well-understood. The effects of differing boiling times on lamb meat and the resultant cooking water were here examined through proteomic evaluation. The longer boiling time was found to result in increased protein aggregation involving particularly proteins such as glyceraldehyde-3-phosphate dehydrogenase, as well as truncation in proteins such as in α-actinin-2. Heat-induced protein backbone cleavage was observed adjacent to aspartic acid and asparagine residues. Side-chain modifications of amino acid residues resulting from the heating, including oxidation of phenylalanine and formation of carboxyethyllysine, were characterized in the cooked samples. Actin and myoglobin bands from the cooked meat per se remained visible on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, even after significant cooking time. These proteins were also found to be the major source of observed heat-induced modifications. This study provides new insights into molecular-level modifications occurring in lamb meat proteins during boiling and a protein chemistry basis for better understanding the effect of this common treatment on the nutritional and functional properties of red-meat-based foods.

  17. A colourimetric method for the determination of the degree of chemical cross-linking in aspartic acid-based polymer gels

    Directory of Open Access Journals (Sweden)

    B. Gyarmati

    2015-02-01

    Full Text Available A 2,4,6-trinitrobenzenesulphonic acid (TNBS-based assay is developed to determine the degree of chemical cross-linking in aspartic acid-based polymer gels. The conventional colourimetric method for the quantitative determination of amine groups is difficult to use in polymer networks; thus, an improved method is developed to analyse polymer gels swollen in dimethyl sulfoxide (DMSO. Reaction products of the derivatizing reaction are examined by NMR. The chemical stability of the reagent is increased in DMSO, and the method shows satisfactory linearity and accuracy. The degree of chemical cross-linking in the investigated gels is close to its theoretical maximum, but the conversion of the pendant amine groups to cross-linking points is strongly dependent on the feed composition of the gels.

  18. Synthesis and Anchoring of Antineoplastic Ferrocene and Phthalocyanine Derivatives on Water-Soluble Polymeric Drug Carriers Derived from Lysine and Aspartic Acid

    Science.gov (United States)

    Maree, M. David; Neuse, Eberhard W.; Erasmus, Elizabeth; Swarts, Jannie C.

    2008-01-01

    The general synthetic strategy towards water-soluble biodegradable drug carriers and the properties that they must have are discussed. The syntheses of water-soluble biodegradable copolymers of lysine and aspartic acid as potential drug-delivering devices, having amine-functionalised side chains are then described. Covalent anchoring of carboxylic acid derivatives of the antineoplastic ferrocene and photodynamically active phthalocyanine moieties to the amine-containing drug carrier copolymers under mild coupling conditions has been achieved utilising the coupling reagent O-benzotriazolyl-N,N,N′,N′-tetramethyluronium hexafluorophosphate to promote formation of the biodegradable amide bond. Even though the parent antineoplastic ferrocene and phthalocyanine derivatives are themselves insoluble in water at pH < 7, the new carrier-drug conjugates that were obtained are well water-soluble. PMID:18288243

  19. The crystal structure of asparaginyl-tRNA synthetase from Thermus thermophilus and its complexes with ATP and asparaginyl-adenylate: the mechanism of discrimination between asparagine and aspartic acid.

    Science.gov (United States)

    Berthet-Colominas, C; Seignovert, L; Härtlein, M; Grotli, M; Cusack, S; Leberman, R

    1998-01-01

    The crystal structure of Thermus thermophilus asparaginyl-tRNA synthetase has been solved by multiple isomorphous replacement and refined at 2.6 A resolution. This is the last of the three class IIb aminoacyl-tRNA synthetase structures to be determined. As expected from primary sequence comparisons, there are remarkable similarities between the tertiary structures of asparaginyl-tRNA synthetase and aspartyl-tRNA synthetase, and most of the active site residues are identical except for three key differences. The structure at 2.65 A of asparaginyl-tRNA synthetase complexed with a non-hydrolysable analogue of asparaginyl-adenylate permits a detailed explanation of how these three differences allow each enzyme to discriminate between their respective and very similar amino acid substrates, asparagine and aspartic acid. In addition, a structure of the complex of asparaginyl-tRNA synthetase with ATP shows exactly the same configuration of three divalent cations as previously observed in the seryl-tRNA synthetase-ATP complex, showing that this a general feature of class II synthetases. The structural similarity of asparaginyl- and aspartyl-tRNA synthetases as well as that of both enzymes to the ammonia-dependent asparagine synthetase suggests that these three enzymes have evolved relatively recently from a common ancestor. PMID:9582288

  20. 40 CFR 180.202 - p-Chlorophenoxyacetic acid; tolerances for residues.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false p-Chlorophenoxyacetic acid; tolerances... Tolerances § 180.202 p-Chlorophenoxyacetic acid; tolerances for residues. (a) General. A tolerance is established for the combined residues of the plant regulator p-chlorophenoxyacetic acid and its metabolite...

  1. Size dependent electrical and magnetic properties of ZnFe2O4 nanoparticles synthesized by the combustion method: Comparison between aspartic acid and glycine as fuels

    Science.gov (United States)

    Shanmugavani, A.; Kalai Selvan, R.; Layek, Samar; Sanjeeviraja, C.

    2014-03-01

    Using two different fuels such as aspartic acid and glycine, the spinel zinc ferrite nanoparticles were synthesized by the combustion method at different pH values. The thermochemical calculations for both the fuel assisted materials and its adiabatic flame temperature were calculated. The X-ray diffraction (XRD) pattern revealed the formation of single phase ZnFe2O4 with high crystallinity. The characteristic functional groups of Fe3O and Zn3O were identified through FTIR analysis. Uniform size distribution of spherical particle in the average size range of 35-100 nm was inferred from SEM images. The room temperature DC conductivities of ZnFe2O4 particles prepared by using aspartic and glycine are in the order of 10-7 and 10-8 respectively. The dielectric spectral analysis inferred that the obtained dielectric constant is high at low frequency and decreases with increase in frequency. This dielectric behavior is in accordance with the Maxwell-Wagner interfacial polarization. VSM and Mössbauer analysis revealed that the prepared material exhibits paramagnetic behavior and Fe3+ state of iron content in ZnFe2O4 at room temperature.

  2. Finding coevolving amino acid residues using row and column weighting of mutual information and multi-dimensional amino acid representation

    DEFF Research Database (Denmark)

    Oliveira, Rodrigo Gouveia; Pedersen, Anders Gorm

    2007-01-01

    ABSTRACT: BACKGROUND: Some amino acid residues functionally interact with each other. This interaction will result in an evolutionary co-variation between these residues - coevolution. Our goal is to find these coevolving residues. RESULTS: We present six new methods for detecting coevolving...... residues. Among other things, we suggest measures that are variants of Mutual Information, and measures that use a multidimensional representation of each residue in order to capture the physico-chemical similarities between amino acids. We created a benchmarking system, in silico, able to evaluate...

  3. N-叔丁氧羰基-L-天冬氨酸-β-苄酯的合成%Synthesis of N-tertbutyloxycarbonyl-L-aspartic acid-β-benzylester

    Institute of Scientific and Technical Information of China (English)

    钟飞; 党明珠

    2014-01-01

    从L-天冬氨酸出发,分两步反应,得到目标产物N-叔丁氧羰基-L-天冬氨酸-β-苄酯,总收率可达到58%,结构经ESI-MS、IR、1HNMR、13CNMR等表征。%The N-tertbutyloxycarbonyl-L-aspartic acid-β-benzylester was synthesized started from L-aspartic acid. The structure was characterized by ESI-MS, IR, 1HNMR and 13CNMR.

  4. Replacement of glycine 232 by aspartic acid in the KdpA subunit broadens the ion specificity of the K(+)-translocating KdpFABC complex.

    Science.gov (United States)

    Schrader, M; Fendler, K; Bamberg, E; Gassel, M; Epstein, W; Altendorf, K; Dröse, S

    2000-01-01

    Replacement of glycine residue 232 with aspartate in the KdpA subunit of the K(+)-translocating KdpFABC complex of Escherichia coli leads to a transport complex that has reduced affinity for K(+) and has lost the ability to discriminate Rb(+) ions (, J. Biol. Chem. 270:6678-6685). This glycine residue is the first in a highly conserved GGG motif that was aligned with the GYG sequence of the selectivity filter (P- or H5-loop) of K(+) channels (, Nature. 371:119-122). Investigations with the purified and reconstituted KdpFABC complex using the potential sensitive fluorescent dye DiSC(3)(5) and the "caged-ATP/planar bilayer method" confirm the altered ion specificity observed in uptake measurements with whole cells. In the absence of cations a transient current was observed in the planar bilayer measurements, a phenomenon that was previously observed with the wild-type enzyme and with another kdpA mutant (A:Q116R) and most likely represents the movement of a protein-fixed charge during a conformational transition. After addition of K(+) or Rb(+), a stationary current could be observed, representing the continuous pumping activity of the KdpFABC complex. In addition, DiSC(3)(5) and planar bilayer measurements indicate that the A:G232D Kdp-ATPase also transports Na(+), Li(+), and H(+) with a reduced rate. Similarities to mutations in the GYG motif of K(+) channels are discussed. PMID:10920013

  5. Arginine-glycine-aspartic acid-polyethylene glycol-polyamidoamine dendrimer conjugate improves liver-cell aggregation and function in 3-D spheroid culture.

    Science.gov (United States)

    Chen, Zhanfei; Lian, Fen; Wang, Xiaoqian; Chen, Yanling; Tang, Nanhong

    The polyamidoamine (PAMAM) dendrimer, a type of macromolecule material, has been used in spheroidal cell culture and drug delivery in recent years. However, PAMAM is not involved in the study of hepatic cell-spheroid culture or its biological activity, particularly in detoxification function. Here, we constructed a PAMAM-dendrimer conjugate decorated by an integrin ligand: arginine-glycine-aspartic acid (RGD) peptide. Our studies demonstrate that RGD-polyethylene glycol (PEG)-PAMAM conjugates can promote singly floating hepatic cells to aggregate together in a sphere-like growth with a weak reactive oxygen species. Moreover, RGD-PEG-PAMAM conjugates can activate the AKT-MAPK pathway in hepatic cells to promote cell proliferation and improve basic function and ammonia metabolism. Together, our data support the hepatocyte sphere treated by RGD-PEG-PAMAM conjugates as a potential source of hepatic cells for a biological artificial liver system.

  6. Optical reflectance, optical refractive index and optical conductivity measurements of nonlinear optics for L-aspartic acid nickel chloride single crystal

    Science.gov (United States)

    Anbazhagan, G.; Joseph, P. S.; Shankar, G.

    2013-03-01

    Single crystals of L-aspartic acid nickel chloride (LANC) were grown by the slow evaporation technique at room temperature. The grown crystals were subjected to Powder X-ray diffraction studies to confirm the crystal structure. The modes of vibration of different molecular groups present in LANC have been identified by FTIR spectral analysis. Optical transferency of the grown crystal was investigated by UV-Vis-NIR spectrum. The lower optical cut off wavelength for this crystal is observed at 240 nm and energy band gap 5.179 eV. The optical reflectance and optical refractive index studies have been carried out in this crystal. Finally, the optical conductivity and electrical conductivity studies have been carried out on LANC single crystal.

  7. Effect of Xingnaojing Injection (醒脑静注射液) on Hippocampal N-methyl-D-aspartic Acid Receptors of Focal Cerebral Ischemia in Rats

    Institute of Scientific and Technical Information of China (English)

    沈思钰; 蔡定芳; 陈伟华; 刘静; 陈虎; 应健

    2003-01-01

    Objective: To observe and elucidate the neuroprotective effect of Xingnaojing (XNJ) injection on hippocampal N-methyl-D-aspartic acid (NMDA) receptors of focal cerebral ischemia in rats. Methods: Cerebral ischemia was established by occluding the middle cerebral artery with an intraluminal suture technique in rats. Neurological deficit score, infarct volume and quantity of NMDA receptors were estimated in all groups and compared. Results: After being treated with XNJ, the score decreased in the initial 6 hours and infarct volume decreased in 24 hours. And within 24 hours,the quantity of NMDA receptors obviously decreased compared with the model group(P<0.01). It indicated that XNJ could ameliorate neurological behavior of middle cerebral artery occlusion rats and down-regulate the expression of hippocampal NMDA receptors. Conclusion: The neuroprotective effect of XNJ on focal cerebral ischemia is possibly related to down-regulating the expression of NMDA receptors in rats.

  8. Integrin αvβ3 as a Promising Target to Image Neoangiogenesis Using In-House Generator-Produced Positron Emitter (68)Ga-Labeled DOTA-Arginine-Glycine-Aspartic Acid (RGD) Ligand.

    Science.gov (United States)

    Vatsa, Rakhee; Bhusari, Priya; Kumar, Sunil; Chakraborty, Sudipta; Dash, Ashutosh; Singh, Gurpreet; Dhawan, Devinder Kumar; Shukla, Jaya; Mittal, Bhagwant Rai

    2015-06-01

    For the growth and spread of a tumor beyond 2 mm, angiogenesis plays a crucial role, and association of various integrins with angiogenesis is evidential. The aim of the study was radiolabeling of DOTA-chelated RGD (arginine-glycine-aspartic acid) peptide with (68)Ga for PET imaging in locally advanced breast carcinoma. DOTA-RGD was incubated with (68)GaCl3, eluted in 0.05 m HCl. Elution volume, peptide amount, and reaction pH were studied. Radio-ITLC, gas chromatography, endotoxin, and sterility testing were performed. Serial (n=3) and whole-body (n=2) PET/CT imaging was done on patients post i.v. injection of 111-185 MBq of (68)Ga-DOTA-RGD. Maximum radiolabeling yield was achieved with 3 mL elution volume of 15-20 μg peptide at pH 3.5-4.0 with 10 minutes of incubation at 95°C. Product samples were sterile having 99.5% radiochemical purity with residual ethanol content and endotoxins in injectable limits. Intense radiotracer uptake was noticed in the tumor with SUVmax 15.3 at 45 minutes in serial images. Physiological radiotracer uptake was seen in the liver, spleen, ventricles, and thyroid with excretion through the kidneys. The authors concluded that (68)Ga-DOTA-RGD has the potential for imaging α,vβ3 integrin-expressing tumors.

  9. Effect of Amino Acid Residue and Oligosaccharide Chain Chemical Modifications on Spectral and Hemagglutinating Activity of Millettia dielsiana Harms. ex Diels. Lectin

    Institute of Scientific and Technical Information of China (English)

    Shun GAO; Jie AN; Chuan-Fang WU; Ying GU; Fang CHEN; Yuan YU; Qia-Qing WU; Jin-Ku BAO

    2005-01-01

    The effects of modifying the carbohydrate chain and amino acids on the conformation and activity of Millettia dielsiana Harms. ex Diels. lectin (MDL) were studied by hemagglutination, fluorescence and circular dichroism analysis. The modification of tryptophan residues led to a compete loss of hemagglutinating activity; however, the addition of mannose was able to prevent this loss of activity. The results indicate that two tryptophan residues are involved in the carbohydrate-binding site. Modifications of the carboxyl group residues produced an 80% loss of activity, but the presence of mannose protected against the modification. The results suggest that the carboxyl groups of aspartic and glutamic acids are involved in the carbohydrate-binding site of the lectin. However, oxidation of the carbohydrate chain and modification of the histidine and arginine residues did not affect the hemagglutinating activity of MDL. Fluorescence studies of MDL indicate that tryptophan residues are present in a relatively hydrophobic region, and the binding of mannose to MDL could quench tryptophan fluorescence without any change in λmax. The circular dichroism spectrum showed that all of these modifications affected the conformation of the MDL molecule to different extents, except the modification of arginine residues. Fluorescence quenching showed that acrylamide and iodoacetic acids are able to quench 77% and 98% of the fluorescence of tryptophan in MDL, respectively.However, KI produced a barely perceptible effect on the fluorescence of MDL, even when the concentration of I- was 0.15 M. This demonstrates that most of tryptophan residues are located in relatively hydrophobic or negatively charged areas near the surface of the MDL molecule.

  10. Dihedral angle preferences of DNA and RNA binding amino acid residues in proteins.

    Science.gov (United States)

    Ponnuraj, Karthe; Saravanan, Konda Mani

    2017-04-01

    A protein can interact with DNA or RNA molecules to perform various cellular processes. Identifying or analyzing DNA/RNA binding site amino acid residues is important to understand molecular recognition process. It is quite possible to accurately model DNA/RNA binding amino acid residues in experimental protein-DNA/RNA complex by using the electron density map whereas, locating/modeling the binding site amino acid residues in the predicted three dimensional structures of DNA/RNA binding proteins is still a difficult task. Considering the above facts, in the present work, we have carried out a comprehensive analysis of dihedral angle preferences of DNA and RNA binding site amino acid residues by using a classical Ramachandran map. We have computed backbone dihedral angles of non-DNA/RNA binding residues and used as control dataset to make a comparative study. The dihedral angle preference of DNA and RNA binding site residues of twenty amino acid type is presented. Our analysis clearly revealed that the dihedral angles (φ, ψ) of DNA/RNA binding amino acid residues prefer to occupy (-89° to -60°, -59° to -30°) bins. The results presented in this paper will help to model/locate DNA/RNA binding amino acid residues with better accuracy.

  11. In vitro characterization of pH-sensitive azithromycin-loaded methoxy poly (ethylene glycol)-block-poly (aspartic acid-graft-imidazole) micelles.

    Science.gov (United States)

    Teng, Fangfang; Deng, Peizong; Song, Zhimei; Zhou, Feilong; Feng, Runliang; Liu, Na

    2017-02-09

    In order to improve azithromycin's antibacterial activity in acidic medium, monomethoxy poly (ethylene glycol)-block-poly (aspartic acid-graft-imidazole) copolymer was synthesized through allylation, free radical addition, ring-opening polymerization and amidation reactions with methoxy poly (ethylene glycol) as raw material. Drug loading capacity and encapsulation efficiency of azithromycin-loaded micelles prepared via thin film hydration method were 11.58±0.86% and 96.06±1.93%, respectively. The drug-loaded micelles showed pH-dependent property in the respects of particle size, zeta potential at the range of pH 5.5-7.8. It could control drug in vitro release and demonstrate higher release rate at pH 6.0 than that at pH 7.4. In vitro antibacterial experiment indicated that the activity of azithromycin-loaded micelles against S. aureus was superior to free azithromycin in medium at both pH 6.0 and pH 7.4. Using fluorescein as substitute with pH-dependent fluorescence decrease property, laser confocal fluorescence microscopy analysis confirmed that cellular uptake of micelles was improved due to protonation of copolymer's imidazole groups at pH 6.0. The enhanced cellular uptake and release of drug caused its activity enhancement in acidic medium when compared with free drug. The micellar drug delivery system should be potential application in the field of bacterial infection treatment.

  12. Phosphorous acid residues in apples after foliar fertilization: results of field trials.

    Science.gov (United States)

    Malusà, E; Tosi, L

    2005-06-01

    The levels of phosphorous acid residues in apples after foliar fertilization with P fertilizers and after treatment with a phosphonate fungicide (Fosetyl-Al) were determined and compared. Two field trials and a glasshouse experiment, using different genotypes and plants of different age, were carried out and monitored over a three-year period. Phosphorous acid residues were found in apples after application of foliar P fertilizers. Concentrations of the residues ranged between 0.02 and 14 mg kg(-1) depending on the phosphorous acid content in the fertilizer used and the plant size and yield. The treatments induced an accumulation of the residue in the course of the experiments, which in some cases reached a level exceeding the maximum limit set by EU legislation. Residues were also detected in other plant organs, i.e., roots and buds. Plants treated with Fosetyl-Al contained phosphorous acid residues in their fruits and buds two years after the suspension of the treatment, suggesting a long-term persistence of the substance in plant storage organs. A second experiment, involving treatment of trees with seven foliar fertilizers of different composition, also induced accumulation of phosphorous acid residues in fruits. It is concluded that a wide array of foliar products containing phosphorous acid, even as a minor component, could mimic the residue effect of phosphonate fungicide treatments.

  13. IgE binding to peanut allergens is inhibited by combined D-aspartic and D-glutamic acids

    Science.gov (United States)

    D-amino acids (D-aas) are reported to bind to IgE antibodies from people with allergy and asthma. The objectives of this study were to determine if D-aas bind or inhibit IgE binding to peanut allergens, and if they are more effective than L-amino acids (L-aas) in this respect. Several D-aa cocktails...

  14. Centrally mediated ejaculatory response via sympathetic outflow in rats: role of N-methyl-D-aspartic acid receptors in paraventricular nucleus.

    Science.gov (United States)

    Xia, J-D; Chen, J; Sun, H-J; Zhou, L-H; Zhu, G-Q; Chen, Y; Dai, Y-T

    2017-01-01

    Ejaculation is mediated by a spinal generator, which integrates inputs related to the sexual activity and coordinates sympathetic, parasympathetic, and motor outflow. Previous clinical studies indicate that primary premature ejaculation is related to the hyperactivity of the sympathetic nervous system. In this study, we explored the roles of N-methyl-D-aspartic acid (NMDA) receptors in paraventricular nucleus of the hypothalamus (PVN) on ejaculatory responses and its potential mechanism in the rats. We found that microinjection of 0.20 nmol NMDA into the PVN reduced the latency of intromission and facilitated ejaculation during copulation. Moreover, delayed ejaculation and intromission were observed after the rats were microinjected with NMDA receptor antagonist D (-)-2-Amino-5-phosphonopentanoic acid (AP-5). However, we discovered that microinjection of NMDA into PVN significantly increased baseline lumbar splanchnic nerve activity (LSNA), and the NMDA dose was positively correlated with the increased LSNA (r = 0.875, p = 0.04). Meanwhile, the plasma norepinephrine level in rats injected with NMDA was much higher than that in rats injected with saline (1453.4 ± 136.4 pg/mL vs. 492.3 ± 36.8 pg/mL, p ejaculation through enhancing the activity of sympathetic system.

  15. Synthesis and characterization of novel water-soluble polyamide based on spermine and aspartic acid as a potential gene delivery vehicle

    Directory of Open Access Journals (Sweden)

    2008-05-01

    Full Text Available We developed a novel and convenient method for the synthesis of a potentially safe non-viral gene delivery vehicle based on the cationic block copolymer of spermine and aspartic acid (ASSP and coupled it with polyethylene glycol (PEG. The copolymer ASSP was prepared by direct polycondensation in the ionic liquid, butylmethylimidazolium hexafluorophosphate, using triphenyl phosphite as the condensing agent under mild reaction conditions. The highly hydrophobic ASSP was transformed into a water soluble hydrophilic micelle by coupling ASSP with polyethylene glycol (PEG using the same ionic liquid and 1,1-carbonyl diimidazole as the condensing agent without harsh conditions. The polycationic ASSP-PEG was then used to condense calf thymus and plasmid deoxyribonuclceic acids (DNAs in Tris-HCl buffer (pH 7.4 to get a series of block ionomer complexes with various charge ratios. The physicochemical properties of the copolymer micelle and the DNA polyplexes were studied using fourier transform-infrared (FTIR, nuclear magnetic resonance (NMR and circular dichroism (CD spectroscopy, matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS, differential scanning calorimetry (DSC, transmission electron microscopy (TEM and particle size measurements. It was observed that the DNA was condensed to compact particles by its interaction with the copolymer. Since DNA condensation to nano/micrometer sized particles is essential for gene delivery, our results indicate a potential use of the copolymer for gene delivery applications.

  16. The calmodulin-dependent protein kinase II inhibitor KN-93 protects rat cerebral cortical neurons from N-methyl-D-aspartic acid-induced injury

    Institute of Scientific and Technical Information of China (English)

    Xuewen Liu; Cui Ma; Ruixian Xing; Weiwei Zhang; Buxian Tian; Xidong Li; Qiushi Li; Yanhui Zhang

    2013-01-01

    In this study, primary cultured cerebral cortical neurons of Sprague-Dawley neonatal rats were treated with 0.25, 0.5, and 1.0 μM calmodulin-dependent protein kinase II inhibitor KN-93 after 50 μM N-methyl-D-aspartic acid-induced injury. Results showed that, compared with N-methyl-Daspartic acid-induced injury neurons, the activity of cells markedly increased, apoptosis was significantly reduced, leakage of lactate dehydrogenase decreased, and intracellular Ca2+ concentrations in neurons reduced after KN-93 treatment. The expression of caspase-3, phosphorylated calmodulin-dependent protein kinase II and total calmodulin-dependent protein kinase II protein decreased after KN-93 treatment. And the effect was apparent at a dose of 1.0 μM KN-93. Experimental findings suggest that KN-93 can induce a dose-dependent neuroprotective effect, and that the underlying mechanism may be related to the down-regulation of caspase-3 and calmodulin- dependent protein kinase II expression.

  17. Endocytosis of the Aspartic Acid/Glutamic Acid Transporter Dip5 Is Triggered by Substrate-Dependent Recruitment of the Rsp5 Ubiquitin Ligase via the Arrestin-Like Protein Aly2 ▿

    Science.gov (United States)

    Hatakeyama, Riko; Kamiya, Masao; Takahara, Terunao; Maeda, Tatsuya

    2010-01-01

    Endocytosis of nutrient transporters is stimulated under various conditions, such as elevated nutrient availability. In Saccharomyces cerevisiae, endocytosis is triggered by ubiquitination of transporters catalyzed by the E3 ubiquitin ligase Rsp5. However, how the ubiquitination is accelerated under certain conditions remains obscure. Here we demonstrate that closely related proteins Aly2/Art3 and Aly1/Art6, which are poorly characterized members of the arrestin-like protein family, mediate endocytosis of the aspartic acid/glutamic acid transporter Dip5. In aly2Δ cells, Dip5 is stabilized at the plasma membrane and is not endocytosed efficiently. Efficient ubiquitination of Dip5 is dependent on Aly2. aly1Δ cells also show deficiency in Dip5 endocytosis, although less remarkably than aly2Δ cells. Aly2 physically interacts in vivo with Rsp5 at its PY motif and also with Dip5, thus serving as an adaptor linking Rsp5 with Dip5 to achieve Dip5 ubiquitination. Importantly, the interaction between Aly2 and Dip5 is accelerated in response to elevated aspartic acid availability. This result indicates that the regulation of Dip5 endocytosis is accomplished by dynamic recruitment of Rsp5 via Aly2. PMID:20956561

  18. Fractional Precipitation of Amino Acids from Agro-industrial Residues Using Ethanol

    NARCIS (Netherlands)

    Widyarani, Rani; Bowden, Nathan A.; Kolfschoten, Ruben C.; Sanders, Johan P.M.; Bruins, Marieke E.

    2016-01-01

    Amino acids are important in human and animal diet, as well as being potential feedstocks for chemical production. Amino acids can be obtained from protein after hydrolysis. In addition, several agro-industrial residues already contain a mixture of free amino acids. The objective of this study wa

  19. The effect of delignification process with alkaline peroxide on lactic acid production from furfural residues

    Directory of Open Access Journals (Sweden)

    Yong Tang

    2012-11-01

    Full Text Available Furfural residues produced from the furfural industry were investigated as a substrate for lactic acid production by simultaneous saccharification and fermentation (SSF. Alkaline peroxide was used for delignification of furfural residues to improve the final lactic acid concentration. The residue was treated with 1.3% to 1.7% hydrogen peroxide at 80 °C for 1 h with a substrate concentration of 3.33%. SSF of furfural residues with different delignification degrees were carried out to evaluate the effect of delignification degree on lactic acid production. Using corn hydrolysates/ furfural residues as substrates, SSF with different media were carried out to investigate the effect of lignin on the interaction between enzymes and lactic acid bacteria. Lactic acid bacteria had a negative effect on cellulase, thus resulting in the reduction of enzyme activity. Lignin and nutrients slowed down the decreasing trend of enzyme activity. A higher delignification resulted in a slower fermentation rate and lower yield due to degradation products of lignin and the effect of lignin on the interaction between enzymes and lactic acid bacteria. For the purpose of lactic acid production, a moderate delignification (furfural residues with the lignin content of 14.8% was optimum.

  20. Selective retrograde labeling of lateral olivocochlear neurons in the brainstem based on preferential uptake of 3H-D-aspartic acid in the cochlea

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, A.F.; Schwartz, I.R.; Helfert, R.H.; Keithley, E.; Wang, Z.X.

    1987-01-22

    We have previously shown that perfusion of the gerbil cochlea with probe concentrations of /sup 3/H-D-aspartic acid (D-ASP) results in immediate, selective labeling of 50-60% of the efferent terminals under the inner hair cells, presumably by high-affinity uptake. The present study was undertaken to determine the origin of these endings. Twenty-four hours after cochlear perfusion with D-ASP, labeled neurons were observed in the ipsilateral, and to a much lesser extent in the contralateral, lateral superior olivary nucleus (LSO). The cells were small, primarily fusiform, and showed fewer synaptic contacts than other LSO cells. Combined transport of D-ASP and horseradish peroxidase indicated that all olivocochlear neurons within the LSO that projected to the injected cochlea were labeled by D-ASP. Labeled fibers coursed dorsally from the LSO, joined contralateral fibers that had passed under the floor of the fourth ventricle, and entered the VIIIth nerve root at its ventromedial edge. Adjacent to the ventral cochlear nucleus (VCN), densely labeled collateral fibers crossed the nerve root to enter the VCN. Labeled fibers and terminals were prominent in the central VCN. Neither retrograde transport of D-ASP by medial olivocochlear and vestibular efferents nor anterograde transport by VIIIth nerve afferents was observed. The D-ASP-labeled cells and fibers are clearly lateral olivocochlear efferents. Retrograde transport of D-ASP thus allows the cells, axons, and collaterals of the lateral olivocochlear system to be studied, morphologically, in isolation from other cells that project to the cochlea. Since the olivocochlear neurons are almost certainly cholinergic, retrograde amino acid transport does not necessarily identify the primary neurotransmitter of a neuron. Rather, it indicates the presence of selective uptake by the processes of that neuron at the site of amino acid injection.

  1. In silico identification and crystal structure validation of caspase-3 inhibitors without a P1 aspartic acid moiety

    Science.gov (United States)

    Ganesan, Rajkumar; Jelakovic, Stjepan; Mittl, Peer R. E.; Caflisch, Amedeo; Grütter, Markus G.

    2011-01-01

    Using a fragment-based docking procedure, several small-molecule inhibitors of caspase-3 were identified and tested and the crystal structures of three inhibitor complexes were determined. The crystal structures revealed that one inhibitor (NSC 18508) occupies only the S1 subsite, while two other inhibitors (NSC 89167 and NSC 251810) bind only to the prime part of the substrate-binding site. One of the major conformational changes observed in all three caspase-3–inhibitor complexes is a rotation of the Tyr204 side chain, which blocks the S2 subsite. In addition, the structural variability of the residues shaping the S1–S4 as well as the S1′ subsites supports an induced-fit mechanism for the binding of the inhibitors in the active site. The high-resolution crystal structures reported here provide novel insights into the architecture of the substrate-binding site, which might be useful for the design of more potent caspase inhibitors. PMID:21821879

  2. Finding coevolving amino acid residues using row and column weighting of mutual information and multi-dimensional amino acid representation

    Directory of Open Access Journals (Sweden)

    Pedersen Anders G

    2007-10-01

    Full Text Available Abstract Background Some amino acid residues functionally interact with each other. This interaction will result in an evolutionary co-variation between these residues – coevolution. Our goal is to find these coevolving residues. Results We present six new methods for detecting coevolving residues. Among other things, we suggest measures that are variants of Mutual Information, and measures that use a multidimensional representation of each residue in order to capture the physico-chemical similarities between amino acids. We created a benchmarking system, in silico, able to evaluate these methods through a wide range of realistic conditions. Finally, we use the combination of different methods as a way of improving performance. Conclusion Our best method (Row and Column Weighed Mutual Information has an estimated accuracy increase of 63% over Mutual Information. Furthermore, we show that the combination of different methods is efficient, and that the methods are quite sensitive to the different conditions tested.

  3. An aspartic acid at amino acid 108 is required to rescue infectious virus after transfection of a poliovirus cDNA containing a CGDD but not SGDD amino acid motif in 3Dpol.

    Science.gov (United States)

    Walker, D E; McPherson, D; Jablonski, S A; McPherson, S; Morrow, C D

    1995-01-01

    The poliovirus RNA-dependent RNA polymerase (3Dpol) contains a region of homology centered around the amino acid motif YGDD (amino acids 326 to 329), which has been postulated to be involved in the catalytic activity of the enzyme. Previous studies from this laboratory have used oligonucleotide site-directed mutagenesis to substitute the tyrosine amino acid at this motif with other amino acids (S. A. Jablonski and C. D. Morrow, J. Virol. 67:373-381, 1993). The viruses recovered with 3Dpol genes with a methionine mutation also contained a second mutation at amino acid 108 resulting in a glutamic acid-to-aspartic acid change (3D-E-108 to 3D-D-108) in the poliovirus RNA polymerase. On the basis of these results, we suggested that the amino acid at position 108 might interact with the YGDD region of the poliovirus polymerase. To further investigate this possibility, we have constructed a series of constructs in which the poliovirus RNA polymerases contained a mutation at amino acid 108 (3D-E-108 to 3D-D-108) as well as a mutation in which the tyrosine amino acid (3D-Y-326) was substituted with cysteine (3D-C-326) or serine (3D-S-326). The mutant 3Dpol polymerases were expressed in Escherichia coli, and in vitro enzyme activity was analyzed. Enzymes containing the 3D-D-108 mutation with the wild-type amino acid (3D-Y-326) demonstrated in vitro enzyme activity similar to that of the wild-type enzyme containing 3D-E-108. In contrast, enzymes with the 3D-C-326 or 3D-S-326 mutation had less in vitro activity than the wild type. The inclusion of the second mutation at amino acid 3D-D-108 did not significantly affect the in vitro activity of the polymerases containing 3D-C-326 or 3D-S-326 mutation. Transfections of poliovirus cDNAs containing the substitution at amino acid 326 with or without the second mutation at amino acid 108 were performed. Consistent with previous findings, we found that transfection of poliovirus cDNAs containing the 3D-C-326 or 3D-S-326 mutation in 3

  4. Aspartic acid functionalized water-soluble perylene diimide as “Off-On” fluorescent sensor for selective detection Cu2+ and ATP

    Science.gov (United States)

    Zhong, Lina; Xing, Feifei; Bai, Yueling; Zhao, Yongmei; Zhu, Shourong

    2013-11-01

    Aspartic functionalized water-soluble perylene diimide, N,N‧-di(2-succinic acid)-perylene-3,4,9,10-tetracarboxylic diimide (PASP) has two absorbance maximums at 527 and 498 nm (ε ≈ 1.7 × 104 L cm-1 mol-1) and two emission peaks at 547 and 587 nm respectively. Emission intensities decrease with the increase of PASP concentrations in 20-100 μM ranges. Spectral titrations demonstrate that each PASP can coordinate to two Cu2+ ions in the absence of HEPES buffer. Its stability constant is estimated to be about 1.0 × 1012 L2 mol-2 at pH 7.20 and its coordinate stoichiometry increased to 7.5 in the same pH in the presence of HEPES buffer. The emission of PASP will be completely quenched upon formation of Cu2+ complex. The lowest "turn-off" fluorescence detection limit was calculated to be 0.3 μM Cu2+. PASP-Cu solution was used as a "turn-on" fluorescence biosensor to detect ATP. The sensitivity towards ATP is 0.3 μM in 50 mM HEPES buffer at pH 7.20, which is one of the most sensitive fluorescence sensors.

  5. Interactions of L-Aspartic Acid with Aqueous Solution of 1,2-Propanediol at Different Temperatures: A Volumetric, Compressibility and Viscometric Approach.

    Science.gov (United States)

    Rani, Ruby; Kumar, Ashwani; Sharma, Tanu; Saini, Balwinder; Bamezai, Rajinder Kumar

    2016-01-01

    The volumetric, acoustic and viscometric methods are used for investigating the interactions of L-aspartic acid (Asp) in aqueous solution of 1,2-propanediol (PD) over a temperature of (298.15, 303.15 and 308.15) K at atmospheric pressure. Using the experimental results, the apparent molar volume, Vφ, limiting apparent molar volume, V0φ, the slope, Sv, and partial molar volume of transfer, V0φ,tr, have been calculated from density data. The apparent molar isentropic compressibility, K φ,s, limiting apparent molar isentropic compressibility, K0φ,s, its slope, Sk, and partial molar compressibility of transfer, K0φ,s, tr, have been calculated from speed of sound data. These values are also used for calculating the number of water molecules hydrated, nH, to the Asp. The viscosity data has also been used to determine relative viscosity ηr, viscosity B-coefficients, temperature derivative of B-coefficients, dB/dT and viscosity B-coefficients of transfer, Btr. The calculated parameters have been discussed in terms of various solute-solute and solute-solvent interactions prevailing in these solutions. Further, a detailed insight into the physicochemical interactions between Asp and aqueous PD, e.g., ion-hydrophilic and hydrophilic-hydrophilic interactions along with the structure-making tendency have been retrieved through the perusal of these calculated parameters.

  6. Static and dynamic investigations of poly(aspartic acid) and Pluronic F127 complex prepared by self-assembling in aqueous solution

    Science.gov (United States)

    Nita, Loredana E.; Chiriac, Aurica P.; Bercea, Maria; Nistor, Manuela T.

    2015-12-01

    The present investigation is focused on evaluation of self-assembling ability in aqueous solutions of two water soluble polymers: poly(aspartic acid) (PAS) and Pluronic F127 (PL). The intermolecular complexes, realized between polyacid and neutral copolymer surfactant in different ratios, have been studied by combining various characterization techniques as rheology, DLS, spectroscopy, microscopy, chemical imaging, and zeta potential determination, measurements performed in static and/or dynamic conditions. In static conditions, when the equilibrium state between PAS/PL polymeric pair was reached, and depending on the polymers mixture composition, and of experimental rheological conditions, positive or negative deviations from the additive rule are registered. Conformational changes of the macromolecular chains and correspondingly physical interactions are generated between PL and PAS for self-assembly and the formation of interpolymer complex as suprastructure with micellar configuration. The phenomenon was better evidenced in case of 1/1 wt ratio between the two polymers. In dynamic conditions of determination, during "in situ" evaluation of the hydrodynamic diameter, zeta potential and conductivity, when the equilibrium state is not reached and as result either the intermolecular bonds are not achieved, the self-assembling process is not so obvious evidenced.

  7. Characterization, Genome Sequence, and Analysis of Escherichia Phage CICC 80001, a Bacteriophage Infecting an Efficient L-Aspartic Acid Producing Escherichia coli.

    Science.gov (United States)

    Xu, Youqiang; Ma, Yuyue; Yao, Su; Jiang, Zengyan; Pei, Jiangsen; Cheng, Chi

    2016-03-01

    Escherichia phage CICC 80001 was isolated from the bacteriophage contaminated medium of an Escherichia coli strain HY-05C (CICC 11022S) which could produce L-aspartic acid. The phage had a head diameter of 45-50 nm and a tail of about 10 nm. The one-step growth curve showed a latent period of 10 min and a rise period of about 20 min. The average burst size was about 198 phage particles per infected cell. Tests were conducted on the plaques, multiplicity of infection, and host range. The genome of CICC 80001 was sequenced with a length of 38,810 bp, and annotated. The key proteins leading to host-cell lysis were phylogenetically analyzed. One protein belonged to class II holin, and the other two belonged to the endopeptidase family and N-acetylmuramoyl-L-alanine amidase family, respectively. The genome showed the sequence identity of 82.7% with that of Enterobacteria phage T7, and carried ten unique open reading frames. The bacteriophage resistant E. coli strain designated CICC 11021S was breeding and its L-aspartase activity was 84.4% of that of CICC 11022S.

  8. Cell-free production of integral membrane aspartic acid proteases reveals zinc-dependent methyltransferase activity of the Pseudomonas aeruginosa prepilin peptidase PilD

    Science.gov (United States)

    Aly, Khaled A; Beebe, Emily T; Chan, Chi H; Goren, Michael A; Sepúlveda, Carolina; Makino, Shin-ichi; Fox, Brian G; Forest, Katrina T

    2013-01-01

    Integral membrane aspartic acid proteases are receiving growing recognition for their fundamental roles in cellular physiology of eukaryotes and prokaryotes, and may be medically important pharmaceutical targets. The Gram-negative Pseudomonas aeruginosa PilD and the archaeal Methanococcus voltae FlaK were synthesized in the presence of unilamellar liposomes in a cell-free translation system. Cosynthesis of PilD with its full-length substrate, PilA, or of FlaK with its full-length substrate, FlaB2, led to complete cleavage of the substrate signal peptides. Scaled-up synthesis of PilD, followed by solubilization in dodecyl-β-d-maltoside and chromatography, led to a pure enzyme that retained both of its known biochemical activities: cleavage of the PilA signal peptide and S-adenosyl methionine-dependent methylation of the mature pilin. X-ray fluorescence scans show for the first time that PilD is a zinc-binding protein. Zinc is required for the N-terminal methylation of the mature pilin, but not for signal peptide cleavage. Taken together, our work identifies the P. aeruginosa prepilin peptidase PilD as a zinc-dependent N-methyltransferase and provides a new platform for large-scale synthesis of PilD and other integral membrane proteases important for basic microbial physiology and virulence. PMID:23255525

  9. Accumulation of radioactivity in rat brain and peripheral tissues including salivary gland after intravenous administration of {sup 14}C-D-aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Imai, Kazuhiro; Fukushima, Takeshi; Santa, Tomofumi; Homma, Hiroshi [Tokyo Univ. (Japan). Faculty of Pharmaceutical Sciences; Sugihara, Juko; Kodama, Hirohiko; Yoshikawa, Masayoshi

    1997-03-01

    After the intravenous administration of {sup 14}C-D-aspartic acid (Asp) into Sprague-Dawley rats (male, 7-week-old), the distribution and elimination of radioactivity was investigated by the whole body autoradiography. High radioactivities were detected in pineal gland, pituitary gland and salivary gland at 30 min after administration. The other tissues detected were liver, lung, adrenal gland, pancreas and spleen where D-Asp was reported to occur naturally. After 24 hr, the radioactivities were still detected at high levels in the pineal, pituitary and salivary glands. The data suggested the natural occurrence of D-Asp in salivary gland. After careful examination utilizing fluorescent derivatization and chiral separation by high-performance liquid chromatography, the presence of D-Asp was, for the first time, demonstrated in salivary gland in situ, the concentration of which was 7.85 {+-} 1.0 nmol/g. The administration of {sup 14}C-L-Asp was also carried out. The data suggested that D-Asp in the circulating blood is one of the sources of the tissue D-Asp. (author)

  10. N-methyl-D-aspartic acid receptor 1 (NMDAR1) aggravates secondary inflammatory damage induced by hemin-NLRP3 pathway after intracerebral hemorrhage

    Institute of Scientific and Technical Information of China (English)

    Xun Weng; Yan Tan; Xiang Chu; Xiao-Feng Wu; Rui Liu; Yue Tian; Lin Li

    2015-01-01

    Objective:Inflammation plays a critical role in secondary brain damage after intracerebral hemorrhage (ICH).However,the mechanisms of inflammatory injury following ICH are still unclear,particularly the involvement of NLRP3 inflammasome,which are crucial to sterile inflammatory responses.In this study,we aim to test the hypothesis that NLRP3 signaling pathway takes a vital position in ICH-induced secondary inflammatory damage and detect the role of N-methyl-D-aspartic acid receptor 1 (NMDAR1) in this progress.Methods:ICH was induced in mice by microinjection of hemin into the striatum.The protein levels of NMDAR1,NMDAR1 phosphorylation,NLRP3 and IL-1β were measured by Western blot.The binding of NMDAR1 to NLRP3 was detected by immunoprecipitation.Results:The expression of NMDAR1,NMDAR1 phosphorylation,NLRP3 and IL-1 β were rapidly increased after ICH.Hemin treatment enhanced NMDAR1 expression and NMDAR1 phosphorylation,as well in cultured microglial cells treated by hemin.Hemin up-regulated NLRP3 and IL-1β level,which was reversed by MK801 (NMDAR antagonist) in vitro.Hemin also promoted the binding of NMDAR1 to NLRP3.Conclusion:Our findings suggest that NMDAR1 plays a pivotal role in hemin-induced NLRP3-mediated inflammatory damage through synergistic activation.

  11. Effect of Xingnaojing Injection(醒脑静注射液)on Hippocampal N—methyl—D—aspartic Acid Receptors of Focal Cerebral Ischemia in Rats

    Institute of Scientific and Technical Information of China (English)

    SHENSi-yu; CAIDing-fang; 等

    2003-01-01

    Objective:To observe and elucidate the neuroprotective effect of Xingnaojing(XNJ) injec-tion on hippocampal N-methyl-D-aspartic acid(NMDA) receptors of focal cerebral ischemia in rats.Meth-ods:Cerebral ischemia was established by occluding the middle cerebral artery with an intraluminal suture technique in rats.Neurological deficit score,infarct volume and quantity of NMDA receptors were esti-mated in all groups and compared.Results:After being treated with XNJ,the score decreased in the initial 6 hours and infarct volume decreased in 24 hours.And within 24 hours,the quantity of NMDA receptors obviously decreased compared with the model group(P<0.01).It indicated that XNJ could ameliorate neurological behavior of middle cerebral artery occlusion rats and down-regulate the expression of hipp-ocampal NMDA receptors.Conclusion:The neuroprotective effect of XNJ on focal cerebral ischemia is possibly related to down-regulating the expression of NMDA receptors in rats.

  12. Application of L-Aspartic Acid-Capped ZnS:Mn Colloidal Nanocrystals as a Photosensor for the Detection of Copper (II Ions in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Jungho Heo

    2016-04-01

    Full Text Available Water-dispersible ZnS:Mn nanocrystals (NCs were synthesized by capping the surface with polar L-aspartic acid (Asp molecules. The obtained ZnS:Mn-Asp NC product was optically and physically characterized using the corresponding spectroscopic methods. The ultra violet-visible (UV-VIS absorption spectrum and photoluminescence (PL emission spectrum of the NCs showed broad peaks at 320 and 590 nm, respectively. The average particle size measured from the obtained high resolution-transmission electron microscopy (HR-TEM image was 5.25 nm, which was also in accordance with the Debye-Scherrer calculations using the X-ray diffraction (XRD data. Moreover, the surface charge and degree of aggregation of the ZnS:Mn-Asp NCs were determined by electrophoretic and hydrodynamic light scattering methods, respectively. These results indicated the formation of agglomerates in water with an average size of 19.8 nm, and a negative surface charge (−4.58 mV in water at ambient temperature. The negatively-charged NCs were applied as a photosensor for the detection of specific cations in aqueous solution. Accordingly, the ZnS:Mn-Asp NCs showed an exclusive luminescence quenching upon addition of copper (II cations. The kinetic mechanism study on the luminescence quenching of the NCs by the addition of the Cu2+ ions proposed an energy transfer through the ionic binding between the two oppositely-charged ZnS:Mn-Asp NCs and Cu2+ ions.

  13. Water-soluble lipopolymer delivery of N-methyl-D-aspartic acid receptor 2B siRNA relieves chronic neuropathic pain in rats

    Institute of Scientific and Technical Information of China (English)

    Jianhua Lu; Yuanxiang Tao; Xue Yang; Weifeng Tu; Hao Chen; Jiaxiang Xiong; Chungui Hu

    2011-01-01

    Spinal dorsal horn N-Methyl-D-aspartic acid receptor 2B (NR2B) overexpression plays an important role in the production and maintenance of neuropathic pain. Because small interfering RNA (siRNA) can inhibit NR2B expression, siRNA may provide a novel approach to treat neuropathic pain and possibly nerve injury. However, an efficient and safe vector for NR2B siRNA has not been discovered. This study shows that a water soluble lipopolymer (WSLP) comprised of low molecular weight polyethyleneimine (PEI) and cholesterol can deliver siRNA targeting NR2B for the treatment of neuropathic pain. Results show that intrathecal injection of WSLP/siRNA complexes for 3 days inhibit NR2B gene expression with reductions in mRNA and protein levels by 59% and 54%, respectively, compared with control rats (P < 0.01). Injection of WSLP complexed with scrambled siRNA, or PEI with siRNA did not show this inhibitory effect. Moreover, injection of WSLP/siRNA complexes significantly relieved neuropathic pain at 3, 7, 12, and 21 days, while injection of WSLP with scrambled siRNA or PEI with siRNA did not. These results demonstrate that WSLP can efficiently deliver siRNA targeting NR2B in vivo and relieve neuropathic pain.

  14. Study of interactions of L-aspartic acid and L-glutamic acid with some metal acetates through volumetric behaviour over the temperature range (288.15 to 318.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Banipal, Tarlok S. [Department of Applied Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India)], E-mail: tsbanipal@yahoo.com; Singh, Kultar [Department of Applied Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India); Banipal, Parampaul K. [Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India); Kaur, Jasbir [Department of Applied Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India)

    2008-07-15

    Apparent molar volumes, V{sub 2,{phi}}, of L-aspartic acid and L-glutamic acid have been determined in aqueous solutions of (0.1, 0.25, 0.5, and 1.0) mol . kg{sup -1} of lithium acetate dihydrate, magnesium acetate tetrahydrate, and calcium acetate at T = (288.15, 298.15, 308.15, and 318.15) K by density measurements. The data have been used to calculate partial molar volume, V{sub 2}{sup 0}, and transfer function, {delta}{sub t}V{sup 0}, at infinite dilution from water to aqueous solutions of co-solutes by applying the correction due to ionisation of amino acids. Partial molar expansibilities, V{sub E}{sup 0}, hydration numbers, n{sub H}, and interaction coefficients of amino acids have also been determined. The dependence of above thermodynamic functions on concentration, temperature and nature of co-solute has been discussed in terms of various interactions taking place between hydrophobic and hydrophilic parts of amino acids and ions of co-solutes. Further, a comparison between present work and data reported in the literature for neutral amino acids DL-alanine, DL-{alpha}-amino-n-butyric acid and their corresponding hydroxy derivatives, L-serine and L-threonine in aqueous solutions of these co-solutes has been made.

  15. Toxicity assessment of repeated intravenous injections of arginine–glycine–aspartic acid peptide conjugated CdSeTe/ZnS quantum dots in mice

    Directory of Open Access Journals (Sweden)

    Wang YW

    2014-10-01

    Full Text Available You-Wei Wang, Kai Yang, Hong Tang, Dan Chen, Yun-Long Bai Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China Background: Nanotechnology-based near-infrared quantum dots (NIR QDs have many excellent optical properties, such as high fluorescence intensity, good fluorescence stability, and strong tissue-penetrating ability. Integrin αvß3 is highly and specifically expressed in tumor angiogenic vessel endothelial cells of almost all carcinomas. Recent studies have shown that NIR QDs linked to peptides containing the arginine–glycine–aspartic acid (RGD sequence (NIR QDs-RGD can specifically target integrin αvß3 expressed in endothelial cells of tumor angiogenic vessels in vivo, and they offer great potential for early cancer diagnosis, in vivo tumor imaging, and tumor individualized therapy. However, the toxicity profile of NIR QDs-RGD has not been reported. This study was conducted to investigate the toxicity of NIR QDs-RGD when intravenously administered to mice singly and repeatedly at the dose required for successful tumor imaging in vivo.Materials and methods: A NIR QDs-RGD probe was prepared by linking NIR QDs with the maximum emission wavelength of 800 nm (QD800 to the RGD peptide (QD800-RGD. QD800-RGD was intravenously injected to BALB/C mice once or twice (200 pmol equivalent of QD800 for each injection. phosphate-buffered saline solution was used as control. Fourteen days postinjection, toxicity tests were performed, including complete blood count (white blood cell, red blood cell, hemoglobin, platelets, lymphocytes, and neutrophils and serum biochemical analysis (total protein, albumin, albumin/globulin, aspartate aminotransferase, alanine aminotransferase, and blood urea nitrogen. The coefficients of liver, spleen, kidney, and lung weight to body weight were measured, as well as their oxidation and antioxidation indicators, including

  16. Plant residues: short term effect on sulphate, borate, zinc and copper adsorption by an acid oxisol

    Directory of Open Access Journals (Sweden)

    Dias Ana Cristi Basile

    2003-01-01

    Full Text Available Laboratory experiments were carried out to examine the effects of plant residues on Cu, Zn, B and S adsorption by an acidic oxisol. The plant residues were: black oats (Avena strigosa, oil seed radish(Raphanus sativus, velvet beans (Stizolobium cinereum, and pigeon pea (Cajanus cajan collected at flowering stage. Plant residues increased Cu and Zn adsorptions and decreased B and S adsorptions. The results indicated that for short term effect plant residues decreased the availabilities of Cu and Zn through metal organic complex reactions and increased availabilities of S and B through competition with organic anions by the adsorption sites on soil.

  17. Entropy reduction in unfolded peptides (and proteins) due to conformational preferences of amino acid residues.

    Science.gov (United States)

    Schweitzer-Stenner, Reinhard; Toal, Siobhan E

    2014-11-07

    As established by several groups over the last 20 years, amino acid residues in unfolded peptides and proteins do not exhibit the unspecific random distribution as assumed by the classical random coil model. Individual amino acid residues in small peptides were found to exhibit different conformational preferences. Here, we utilize recently obtained conformational distributions of guest amino acid residues in GxG peptides to estimate their conformational entropy, which we find to be significantly lower than the entropy of an assumed random coil like distribution. Only at high temperature do backbone entropies approach random coil like values. We utilized the obtained backbone entropies of the investigated amino acid residues to estimate the loss of conformational entropy caused by a coil → helix transition and identified two subsets of amino acid residues for which the thus calculated entropy losses correlate well with the respective Gibbs energy of helix formation obtained for alanine based host-guest systems. Calculated and experimentally derived entropic losses were found to be in good agreement. For most of the amino acid residues investigated entropic losses derived from our GxG distributions correlate very well with corresponding values recently obtained from MD simulations biased by conformational propensities derived from truncated coil libraries. Both, conformational entropy and the entropy of solvation exhibit a strong, residue specific temperature dependence, which can be expected to substantially affect the stability of unfolded states. Altogether, our results provide strong evidence for the notion that conformational preferences of amino acid residues matter with regard to the thermodynamics of peptide and protein folding.

  18. Replacement of aspartic acid-96 by asparagine in bacteriorhodopsin slows both the decay of the M intermediate and the associated proton movement.

    Science.gov (United States)

    Holz, M; Drachev, L A; Mogi, T; Otto, H; Kaulen, A D; Heyn, M P; Skulachev, V P; Khorana, H G

    1989-01-01

    The photocycle, electrical charge translocation, and release and uptake of protons from the aqueous phase and release and uptake of protons from the aqueous phase were investigated for bacteriorhodopsin mutants with aspartic acid-96 replaced by asparagine or glutamic acid. At neutral pH the main effect of the Asp-96----Asn mutation is to slow by 2 orders of magnitude the decay of the M intermediate and the concomitant charge displacement associated with the reprotonation of the Schiff base from the cytoplasmic side of the membrane. The proton uptake measured with the indicator dye pyranine is likewise slowed without affecting the stoichiometry of proton pumping. The corresponding results for the Asp-96----Glu mutant, on the other hand, are very close to those for the wild-type protein. These results provide a kinetic explanation for the fact that at pH 7 and saturating light intensities the steady-state proton pumping is almost abolished in the Asp-96----Asn mutant but is close to normal in the Asp-96----Glu mutant. Thus, the pump is simply turning over much more slowly in the Asp-96----Asn mutant. The time constants of the decay of M and the associated charge translocation increase strongly with increasing pH for the Asp-96----Asn mutant but are virtually pH-independent for the Asp-96----Glu mutant and wild-type bacteriorhodopsin. At pH 5 the M decay of the Asp-96----Asn mutant is as fast as for wild type. These results suggest that Asp-96 serves as an internal proton donor in the proton-uptake pathway from the cytoplasm to the Schiff base. PMID:2648392

  19. Dizocilpine (MK-801) induces distinct changes of N-methyl-D-aspartic acid receptor subunits in parvalbumin-containing interneurons in young adult rat prefrontal cortex.

    Science.gov (United States)

    Xi, Dong; Zhang, Wentong; Wang, Huai-Xing; Stradtman, George G; Gao, Wen-Jun

    2009-11-01

    N-methyl-D-aspartic acid receptor (NMDAR) hypofunction has long been implicated in schizophrenia and NMDARs on gamma-aminobutyric acid (GABA)ergic interneurons are proposed to play an essential role in the pathogenesis. However, controversial results have been reported regarding the regulation of NMDAR expression, and direct evidence of how NMDAR antagonists act on specific subpopulations of prefrontal interneurons is missing. We investigated the effects of the NMDAR antagonist dizocilpine (MK-801) on the expression of NMDAR subtypes in the identified interneurons in young adult rat prefrontal cortex (PFC) by using laser microdissection and real-time polymerase chain reaction, combined with Western blotting and immunofluorescent staining. We found that MK-801 induced distinct changes of NMDAR subunits in the parvalbumin-immunoreactive (PV-ir) interneurons vs. pyramidal neurons in the PFC circuitry. The messenger RNA (mRNA) expression of all NMDAR subtypes, including NR1 and NR2A to 2D, exhibited inverted-U dose-dependent changes in response to MK-801 treatment in the PFC. In contrast, subunit mRNAs of NMDARs in PV-ir interneurons were significantly down-regulated at low doses, unaltered at medium doses, and significantly decreased again at high doses, suggesting a biphasic dose response to MK-801. The differential effects of MK-801 in mRNA expression of NMDAR subunits were consistent with the protein expression of NR2A and NR2B subunits revealed with Western blotting and double immunofluorescent staining. These results suggest that PV-containing interneurons in the PFC exhibit a distinct responsiveness to NMDAR antagonism and that NMDA antagonist can differentially and dose-dependently regulate the functions of pyramidal neurons and GABAergic interneurons in the prefrontal cortical circuitry.

  20. An aspartate and a water molecule mediate efficient acid-base catalysis in a tailored antibody pocket.

    Science.gov (United States)

    Debler, Erik W; Müller, Roger; Hilvert, Donald; Wilson, Ian A

    2009-11-03

    Design of catalysts featuring multiple functional groups is a desirable, yet formidable goal. Antibody 13G5, which accelerates the cleavage of unactivated benzisoxazoles, is one of few artificial enzymes that harness an acid and a base to achieve efficient proton transfer. X-ray structures of the Fab-hapten complexes of wild-type 13G5 and active-site variants now afford detailed insights into its mechanism. The parent antibody preorganizes Asp(H35) and Glu(L34) to abstract a proton from substrate and to orient a water molecule for leaving group stabilization, respectively. Remodeling the environment of the hydrogen bond donor with a compensatory network of ordered waters, as seen in the Glu(L34) to alanine mutant, leads to an impressive 10(9)-fold rate acceleration over the nonenzymatic reaction with acetate, illustrating the utility of buried water molecules in bifunctional catalysis. Generalization of these design principles may aid in creation of catalysts for other important chemical transformations.

  1. Coevolution of amino acid residues in the key photosynthetic enzyme Rubisco

    Directory of Open Access Journals (Sweden)

    Kapralov Maxim V

    2011-09-01

    Full Text Available Abstract Background One of the key forces shaping proteins is coevolution of amino acid residues. Knowing which residues coevolve in a particular protein may facilitate our understanding of protein evolution, structure and function, and help to identify substitutions that may lead to desired changes in enzyme kinetics. Rubisco, the most abundant enzyme in biosphere, plays an essential role in the process of carbon fixation through photosynthesis, thus facilitating life on Earth. This makes Rubisco an important model system for studying the dynamics of protein fitness optimization on the evolutionary landscape. In this study we investigated the selective and coevolutionary forces acting on large subunit of land plants Rubisco using Markov models of codon substitution and clustering approaches applied to amino acid substitution histories. Results We found that both selection and coevolution shape Rubisco, and that positively selected and coevolving residues have their specifically favored amino acid composition and pairing preference. The mapping of these residues on the known Rubisco tertiary structures showed that the coevolving residues tend to be in closer proximity with each other compared to the background, while positively selected residues tend to be further away from each other. This study also reveals that the residues under positive selection or coevolutionary force are located within functionally important regions and that some residues are targets of both positive selection and coevolution at the same time. Conclusion Our results demonstrate that coevolution of residues is common in Rubisco of land plants and that there is an overlap between coevolving and positively selected residues. Knowledge of which Rubisco residues are coevolving and positively selected could be used for further work on structural modeling and identification of substitutions that may be changed in order to improve efficiency of this important enzyme in crops.

  2. A conserved aspartic acid is important for agonist (VUAA1 and odorant/tuning receptor-dependent activation of the insect odorant co-receptor (Orco.

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    Brijesh N Kumar

    Full Text Available Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco. An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca(2+ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ~2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels.

  3. A Conserved Aspartic Acid Is Important for Agonist (VUAA1) and Odorant/Tuning Receptor-Dependent Activation of the Insect Odorant Co-Receptor (Orco)

    Science.gov (United States)

    Kumar, Brijesh N.; Taylor, Robert W.; Pask, Gregory M.; Zwiebel, Laurence J.; Newcomb, Richard D.; Christie, David L.

    2013-01-01

    Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco). An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca2+ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ∼2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels. PMID:23894621

  4. Pharmacological characterization of LY233053: A structurally novel tetrazole-substituted competitive N-methyl-D-aspartic acid antagonist with a short duration of action

    Energy Technology Data Exchange (ETDEWEB)

    Schoepp, D.D.; Ornstein, P.L.; Leander, J.D.; Lodge, D.; Salhoff, C.R.; Zeman, S.; Zimmerman, D.M. (Eli Lilly and Company, Indianapolis, IN (USA))

    1990-12-01

    This study reports the activity of a structurally novel excitatory amino acid receptor antagonist, LY233053 (cis-(+-)-4-((2H-tetrazol-5-yl)methyl)piperidine-2-carboxylic acid), the first tetrazole-containing competitive N-methyl-D-aspartic acid (NMDA) antagonist. LY233053 potently inhibited NMDA receptor binding to rat brain membranes as shown by the in vitro displacement of (3H) CGS19755 (IC50 = 107 +/- 7 nM). No appreciable affinity in (3H)alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) or (3H)kainate binding assays was observed (IC50 values greater than 10,000 nM). In vitro NMDA receptor antagonist activity was further demonstrated by selective inhibition of NMDA-induced depolarization in cortical wedges (IC50 = 4.2 +/- 0.4 microM vs. 40 microM NMDA). LY233053 was effective after in vivo systemic administration in a number of animal models. In neonatal rats, LY233053 selectively blocked NMDA-induced convulsions (ED50 = 14.5 mg/kg i.p.) with a relatively short duration of action (2-4 hr). In pigeons, LY233053 potently antagonized (ED50 = 1.3 mg/kg i.m.) the behavioral suppressant effects of 10 mg/kg of NMDA. However, a dose of 160 mg/kg, i.m., was required to produce phencyclidine-like catalepsy in pigeons. In mice, LY233053 protected against maximal electroshock-induced seizures at lower doses (ED50 = 19.9 mg/kg i.p.) than those that impaired horizontal screen performance (ED50 = 40.9 mg/kg i.p.). Cholinergic and GABAergic neuronal degenerations after striatal infusion of NMDA were prevented by single or multiple i.p. doses of LY233053. In summary, the antagonist activity of LY233053 after systemic administration demonstrates potential therapeutic value in conditions of neuronal cell loss due to NMDA receptor excitotoxicity.

  5. Demonstration on Fertilizer Effect of Poly Aspartic Acid on Rice%聚天冬氨酸增效肥在水稻上的应用效果示范

    Institute of Scientific and Technical Information of China (English)

    李梅; 沈文忠; 左其东; 张绪美

    2015-01-01

    Objective] The aim was to provide references for poly aspartic acid applied on rice. [Method] The fertilizer effect of poly aspartic acid on rice was studied, by conducting test. [Result] The results showed that rice plant height increased 2.67 cm compared with conventional fertilization way, and increased 2.97%, by applying poly aspartic acid on rice. The effective panicles increased 25500 ears, and increased the amplitude of 0.85%. Empty abortive rate decreased by 7.26%. Rice yield increased significantly with increase of 635.7 kg/hm2, with the production rate of 8.11%. [Conclusion] Application of poly aspartic acid could obtain obvious increase production effect in the process of rice production.%[目的]为聚天冬氨酸增效肥在水稻上的应用提供技术支撑。[方法]针对聚天冬氨酸增效肥在水稻上应用的实际效果进行试验。[结果]结果表明,与常规施肥方式相比,施用了聚天冬氨酸增效肥的水稻株高增加了2.67 cm,增幅为2.97%;有效穗数增加2.55万穗,增幅为0.85%;空秕率减少了7.26%;水稻产量明显增加,增产635.7 kg/hm2,增产率为8.11%。[结论]水稻生产过程中施用聚天冬氨酸增效肥可取得明显增产增收效果。

  6. Microwave-assisted synthesis, crystal structure and toxicity of L-aspartic acid zinc spiral linear supramolecular polymer

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Youming; LIN; Qi; WEI; Taibao

    2004-01-01

    [1]Prasad, A.S. Nutritional metabolic role of zinc, Fed. Proc., 1967,26(1): 172-185.[2]Slagueiro, M. J., Zubillaga, M. B., Lysionek, A. E. et al., The role of zinc in the growth and development of children, Nutrition,2002, 18: 510-519.[3]Mossad, S. B., Zinc and the common cold: Are we close to a true?Nutrition, 1997, 13: 708-709.[4]Prasad, A. S., Clinical and biochemical manifestations of zinc deficiency in human subjects, J. Am. Coll. Nutr., 1985, 4(1):73-82.[5]Prasad, A. S., Zinc deficiency in sickle cell disease, Prog. Clin.Biol. Res., 1984, 165: 49-58.[6]Prasad, A. S., Discovery of zinc deficiency: Impact on human health, Nutrition, 2001, 17: 685-687.[7]Gao, S. -L., Fan, Y., Hu, R. -Z. et al., Synthesis, properties and phase equilibrian of Zn(NO3)2-Leu-H2O system (25℃), Chem. J.Chinese Universities (in Chinese), 2003, 24(2): 195-199.[8]Viladkar, S., Kamaluddin, Nath, M., Hydrolysis of phosphate by (amino acidato)zinc complexes, Bull. Chem. Soc. Jpn., 1993,66(10): 2922-2926.[9]Ashby, C. I. H., Paton, W. F., Brown, T. L., Nitrogen-14 nuclear quadrupole resonance spectra of the coordinated amino group and of coordinated imidazole. Crystal and molecular structures of chloroglycylglycinato(imidazole)cadmium, J. Am. Chem. Soc.,1980, 102(9): 2990-2998.[10]Jia, D. -Z., Yang, L. -X., Xia, X. et al., Studies on application of microwave heating techniques for the solid state reactions of coordination Compounds (Ⅰ), Chem. J. Chinese Universities (in Chinese), 1997, 18(9): 1432-1435.[11]Lidstrom, P., Tierney, J., Wathey, B. et al., Microwave assisted organic synthesis-a review, Tetrahedron, 2001, 57: 9925-9283.[12]Zhang, Y. M., Bai, J. F., Lu, M. Q. et al., Preparation of amino-acid Zinc and its character, Huaxue Shijie (in Chinese),1997, (2): 82-84.

  7. Structure-function relationships in the Na,K-ATPase. cap alpha. subunit: site-directed mutagenesis of glutamine-111 to arginine and asparagine-122 to aspartic acid generates a ouabain-resistant enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Price, E.M.; Lingrel, J.B.

    1988-11-01

    Na,K-ATPases from various species differ greatly in their sensitivity to cardiac glycosides such as ouabain. The sheep and human enzymes are a thousand times more sensitive than the corresponding ones from rat and mouse. To define the region of the ..cap alpha..1 subunit responsible for this differential sensitivity, chimeric cDNAs of sheep and rat were constructed and expressed in ouabain-sensitive HeLa cells. The construct containing the amino-terminal half of the rat ..cap alpha..1 subunit coding region and carboxyl-terminal half of the sheep conferred the ouabain-resistant phenotype to HeLa cells while the reverse construct did not. This indicates that the determinants involved in ouabain sensitivity are located in the amino-terminal half of the Na,K-ATPase ..cap alpha.. subunit. By use of site-directed mutagenesis, the amino acid sequence of the first extracellular domain (H1-H2) of the sheep ..cap alpha..1 subunit was changed to that of the rat. When expressed in HeLa cells, this mutated sheep ..cap alpha..1 construct, like the rat/sheep chimera, was able to confer ouabain resistance to these cells. Furthermore, similar results were observed when HeLa cells were transfected with a sheep ..cap alpha..1 cDNA containing only two amino acid substitutions. The resistant cells, whether transfected with the rat ..cap alpha..1 cDNA, the rat/sheep chimera, or the mutant sheep ..cap alpha..1 cDNAs, exhibited identical biochemical characteristics including ouabain-inhibitable cell growth, /sup 86/Rb/sup +/ uptake, and Na,K-ATPase activity. These results demonstrate that the presence of arginine and aspartic acid on the amino end and carboxyl end, respectively, of the H1-H2 extracellular domain of the Na,K-ATPase ..cap alpha.. subunit together is responsible for the ouabain-resistant character of the rat enzyme and the corresponding residues in the sheep ..cap alpha..1 subunit (glutamine and asparagine) are somehow involved in ouabain binding.

  8. Preparation of hardened body in calcium carbonate-aspartic acid-chitosan system by using amorphous calcium carbonate; Hishoshitsu tansan calcium wo genryo to suru tansan calcium-asuparaginsan-kitosankei kokatai no sakusei

    Energy Technology Data Exchange (ETDEWEB)

    Yasue, T.; Aigami, H.; Arai, Y. [Nihon University, Tokyo (Japan). Faculty of Science and Engineering

    1998-11-01

    Notice was given on chitosan to discuss fabrication of hardened body in calcium carbonate-aspartic acid-chitosan system. First, aspartic acid (Asp) was adsorbed into surface of amorphous calcium carbonate (ACC). Then, discussions were given on effects of water-solid mass ratio and chitosan amount on compressive strength of the hardened body in the calcium carbonate-chitosan system made by using a flow-in molding process. As a result, approximately the same compressive strength as that of calcium carbonate (calcite type) was obtained when anhydrous ACC as a product of ACC heated at 250 deg C is used as the raw material. Thus, the hardened body in calcium carbonate-aspartic acid-chitosan system was fabricated by using the Asp adsorbed anhydrous ACC as the starting material. The compressive strength decreased with increasing Asp adsorption amount. Therefore, a hardened body was fabricated by using compression molding at 10 MPa, rather than using the flow-in molding process. It was revealed from the results of infrared absorption spectroscopy that the compression molding strengthens the compounding of Asp chemically adsorbed on the ACC surface with chtosan, and improves the compression strength. 23 refs., 8 figs.

  9. Aspartate embedding depth affects pHLIP's insertion pKa.

    Science.gov (United States)

    Fendos, Justin; Barrera, Francisco N; Engelman, Donald M

    2013-07-09

    We have used the pHlow insertion peptide (pHLIP) family to study the role of aspartate embedding depth in pH-dependent transmembrane peptide insertion. pHLIP binds to the surface of a lipid bilayer as a largely unstructured monomer at neutral pH. When the pH is lowered, pHLIP inserts spontaneously across the membrane as a spanning α-helix. pHLIP insertion is reversible when the pH is adjusted back to a neutral value. One of the critical events facilitating pHLIP insertion is the protonation of aspartates in the spanning domain of the peptide: the negative side chains of these residues convert to uncharged, polar forms, facilitating insertion by altering the hydrophobicity of the spanning domain. To examine this protonation mechanism further, we created pHLIP sequence variants in which the two spanning aspartates (D14 and D25) were moved up or down in the sequence. We hypothesized that the aspartate depth in the inserted state would directly affect the proton affinity of the acidic side chains, altering the pKa of pH-dependent insertion. To this end, we also mutated the arginine at position 11 to determine whether arginine snorkeling modulates the insertion pKa by affecting the aspartate depth. Our results indicate that both types of mutations change the insertion pKa, supporting the idea that the aspartate depth is a participating parameter in determining the pH dependence. We also show that pHLIP's resistance to aggregation can be altered with our mutations, identifying a new criterion for improving the performance of pHLIP in vivo when targeting acidic disease tissues such as cancer and inflammation.

  10. The 4-pyridylmethyl ester as a protecting group for glutamic and aspartic acids: 'flipping' peptide charge states for characterization by positive ion mode ESI-MS.

    Science.gov (United States)

    Garapati, Sriramya; Burns, Colin S

    2014-03-01

    Use of the 4-pyridylmethyl ester group for side-chain protection of glutamic acid residues in solid-phase peptide synthesis enables switching of the charge state of a peptide from negative to positive, thus making detection by positive ion mode ESI-MS possible. The pyridylmethyl ester moiety is readily removed from peptides in high yield by hydrogenation. Combining the 4-pyridylmethyl ester protecting group with benzyl ester protection reduces the number of the former needed to produce a net positive charge and allows for purification by RP HPLC. This protecting group is useful in the synthesis of highly acidic peptide sequences, which are often beset by problems with purification by standard RP HPLC and characterization by ESI-MS.

  11. MicroRNA-217 suppresses homocysteine-induced proliferation and migration of vascular smooth muscle cells via N-methyl-D-aspartic acid receptor inhibition.

    Science.gov (United States)

    Duan, Hongyan; Li, Yongqiang; Yan, Lijie; Yang, Haitao; Wu, Jintao; Qian, Peng; Li, Bing; Wang, Shanling

    2016-10-01

    Hyperhomocysteine has become a critical risk for atherosclerosis and can stimulate proliferation and migration of vascular smooth muscle cells (VSMCs). N-methyl-D-aspartic acid receptor (NMDAR) is a receptor of homocysteine and mediates the effects of homocysteine on VSMCs. Bioinformatics analysis has shown NMDAR is a potential target of microRNA-217 (miR-217), which exerts multiple functions in cancer tumorigenesis and carotid plaque progression. In this study, we sought to investigate the role of miR-217 in VSMCs phenotype transition under homocysteine exposure and elucidate its effect on atherosclerotic plaque formation. After treating with several doses of homocysteine (0-8 × 10(-4)  mol/L) for 24 hours, the expression of miR-217 in HA-VSMCs and rat aortic VSMCs was not altered. Intriguingly, the expression of NMDAR mRNA and protein was reduced by homocysteine in a dose-dependent manner. Transfection of miR-217 mimic significantly inhibited the proliferation and migration of VSMCs with homocysteine treatment, while transfection of miR-217 inhibitor promoted VSMCs migration. Moreover, miR-217 mimic down-regulated while miR-217 inhibitor up-regulated NMDAR protein expression but not NMDAR mRNA expression. Through luciferase reporter assay, we showed that miR-217 could directly bind to the 3'-UTR of NMDAR. MiR-217 mimic transfection also released the inhibition of cAMP-response element-binding protein (CREB)-PGC-1α signalling induced by homocysteine. Additionally, restoration of PGC-1α expression via AdPGC-1α infection markedly suppressed VSMCs proliferation through the degradation of NADPH oxidase (NOX1) and reduction of reactive oxygen species (ROS). Collectively, our study identified the role of miR-217 in regulating VSMCs proliferation and migration, which might serve as a target for atherosclerosis therapy.

  12. Agmatine protects Müller cells from high-concentration glucose-induced cell damage via N-methyl-D-aspartic acid receptor inhibition.

    Science.gov (United States)

    Han, Ning; Yu, Li; Song, Zhidu; Luo, Lifu; Wu, Yazhen

    2015-07-01

    Neural injury is associated with the development of diabetic retinopathy. Müller cells provide structural and metabolic support for retinal neurons. High glucose concentrations are known to induce Müller cell activity. Agmatine is an endogenous polyamine, which is enzymatically formed in the mammalian brain and has exhibited neuroprotective effects in a number of experimental models. The aims of the present study were to investigate whether agmatine protects Müller cells from glucose-induced damage and to explore the mechanisms underlying this process. Lactate dehydrogenase activity and tumor necrosis factor-α mRNA expression were significantly reduced in Müller cells exposed to a high glucose concentration, following agmatine treatment, compared with cells not treated with agmatine. In addition, agmatine treatment inhibited glucose-induced Müller cell apoptosis, which was associated with the regulation of Bax and Bcl-2 expression. Agmatine treatment suppressed glucose-induced phosphorylation of mitogen-activated protein kinase (MAPK) protein in Müller cells. The present study demonstrated that the protective effects of agmatine on Müller cells were inhibited by N-methyl-D-aspartic acid (NMDA). The results of the present study suggested that agmatine treatment protects Müller cells from high-concentration glucose-induced cell damage. The underlying mechanisms may relate to the anti-inflammatory and antiapoptotic effects of agmatine, as well as to the inhibition of the MAPK pathway, via NMDA receptor suppression. Agmatine may be of use in the development of novel therapeutic approaches for patients with diabetic retinopathy.

  13. P2X7 receptor antagonists protect against N-methyl-D-aspartic acid-induced neuronal injury in the rat retina.

    Science.gov (United States)

    Sakamoto, Kenji; Endo, Kanako; Suzuki, Taishi; Fujimura, Kyosuke; Kurauchi, Yuki; Mori, Asami; Nakahara, Tsutomu; Ishii, Kunio

    2015-06-05

    Activation of N-methyl-d-aspartic acid (NMDA) receptors followed by a large Ca(2+) influx is thought to be a mechanism of glaucoma-induced neuronal cell death. It is possible that damage-associated molecular patterns leak from injured cells, such as adenosine triphosphate, causing retinal ganglion cell death in glaucoma. In the present study, we histologically investigated whether antagonists of the P2X7 receptor protected against NMDA-induced retinal injury in the rat in vivo. Under ketamine/xylazine anesthesia, male Sprague-Dawley rats were subjected to intravitreal injection of NMDA. We used A438079 (3-(5-(2,3-dichlorophenyl)-1H-tetrazol-1-yl)methyl pyridine) and brilliant blue G as P2X7 receptor antagonists. Upon morphometric evaluation 7 days after an intravitreal injection (200 nmol/eye), NMDA-induced cell loss was apparent in the ganglion cell layer. Intravitreal A438079 (50 pmol/eye) simultaneously injected with NMDA and intraperitoneal brilliant blue G (50 mg/kg) administered just before the NMDA injection as well as 24 and 48h after significantly reduced cell loss. In addition, A438079 decreased the number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells 12h after NMDA injection. P2X7 receptors were immunolocalized in the ganglion cell layer and the inner and outer plexiform layers, whereas the immunopositive P2X7 receptor signal was not detected on the Iba1-positive microglial cells that infiltrated the retina 12h after NMDA injection. The present study shows that stimulation of the P2X7 receptor is involved in NMDA-induced histological damage in the rat retina in vivo. P2X7 receptor antagonists may be effective in preventing retinal diseases caused by glutamate excitotoxicity, such as glaucoma and retinal artery occlusion.

  14. Size dependent electrical and magnetic properties of ZnFe{sub 2}O{sub 4} nanoparticles synthesized by the combustion method: Comparison between aspartic acid and glycine as fuels

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugavani, A. [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Kalai Selvan, R., E-mail: selvankram@buc.edu.in [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Layek, Samar [Department of Physics, Indian institute of Technology, Kanpur 208016 (India); Sanjeeviraja, C. [Department of Physics, Alagappa Chettiar College of Engineering and Technology, Karaikudi- 630 004, Tamil Nadu (India)

    2014-03-15

    Using two different fuels such as aspartic acid and glycine, the spinel zinc ferrite nanoparticles were synthesized by the combustion method at different pH values. The thermochemical calculations for both the fuel assisted materials and its adiabatic flame temperature were calculated. The X-ray diffraction (XRD) pattern revealed the formation of single phase ZnFe{sub 2}O{sub 4} with high crystallinity. The characteristic functional groups of Fe3O and Zn3O were identified through FTIR analysis. Uniform size distribution of spherical particle in the average size range of 35–100 nm was inferred from SEM images. The room temperature DC conductivities of ZnFe{sub 2}O{sub 4} particles prepared by using aspartic and glycine are in the order of 10{sup −7} and 10{sup −8} respectively. The dielectric spectral analysis inferred that the obtained dielectric constant is high at low frequency and decreases with increase in frequency. This dielectric behavior is in accordance with the Maxwell–Wagner interfacial polarization. VSM and Mössbauer analysis revealed that the prepared material exhibits paramagnetic behavior and Fe{sup 3+} state of iron content in ZnFe{sub 2}O{sub 4} at room temperature. - Highlights: • For the first time aspartic acid is used as a fuel to synthesize ZnFe{sub 2}O{sub 4} nanoparticles. • Theoretical adiabatic flame temperature for the formation of ZnFe{sub 2}O{sub 4} is calculated. • Individual spherical shape particles are achieved by combustion synthesis. • Enhanced room temperature conductivity for aspartic acid assisted particles are revealed. • Size dependent electrical and magnetic properties are demonstrated.

  15. A Soluble, Folded Protein without Charged Amino Acid Residues

    DEFF Research Database (Denmark)

    Højgaard, Casper; Kofoed, Christian; Espersen, Roall;

    2016-01-01

    Charges are considered an integral part of protein structure and function, enhancing solubility and providing specificity in molecular interactions. We wished to investigate whether charged amino acids are indeed required for protein biogenesis and whether a protein completely free of titratable ...

  16. Preparation of arginine-glycine-aspartic acid-modified biopolymeric nanoparticles containing epigalloccatechin-3-gallate for targeting vascular endothelial cells to inhibit corneal neovascularization.

    Science.gov (United States)

    Chang, Che-Yi; Wang, Ming-Chen; Miyagawa, Takuya; Chen, Zhi-Yu; Lin, Feng-Huei; Chen, Ko-Hua; Liu, Guei-Sheung; Tseng, Ching-Li

    2017-01-01

    Neovascularization (NV) of the cornea can disrupt visual function, causing ocular diseases, including blindness. Therefore, treatment of corneal NV has a high public health impact. Epigalloccatechin-3-gallate (EGCG), presenting antiangiogenesis effects, was chosen as an inhibitor to treat human vascular endothelial cells for corneal NV treatment. An arginine-glycine-aspartic acid (RGD) peptide-hyaluronic acid (HA)-conjugated complex coating on the gelatin/EGCG self-assembly nanoparticles (GEH-RGD NPs) was synthesized for targeting the αvβ3 integrin on human umbilical vein endothelial cells (HUVECs) in this study, and a corneal NV mouse model was used to evaluate the therapeutic effect of this nanomedicine used as eyedrops. HA-RGD conjugation via COOH and amine groups was confirmed by (1)H-nuclear magnetic resonance and Fourier-transform infrared spectroscopy. The average diameter of GEH-RGD NPs was 168.87±22.5 nm with positive charge (19.7±2 mV), with an EGCG-loading efficiency up to 95%. Images of GEH-RGD NPs acquired from transmission electron microscopy showed a spherical shape and shell structure of about 200 nm. A slow-release pattern was observed in the nanoformulation at about 30% after 30 hours. Surface plasmon resonance confirmed that GEH-RGD NPs specifically bound to the integrin αvβ3. In vitro cell-viability assay showed that GEH-RGD efficiently inhibited HUVEC proliferation at low EGCG concentrations (20 μg/mL) when compared with EGCG or non-RGD-modified NPs. Furthermore, GEH-RGD NPs significantly inhibited HUVEC migration down to 58%, lasting for 24 hours. In the corneal NV mouse model, fewer and thinner vessels were observed in the alkali-burned cornea after treatment with GEH-RGD NP eyedrops. Overall, this study indicates that GEH-RGD NPs were successfully developed and synthesized as an inhibitor of vascular endothelial cells with specific targeting capacity. Moreover, they can be used in eyedrops to inhibit angiogenesis in corneal NV mice.

  17. The Role of Glutamic or Aspartic Acid in Position Four of the Epitope Binding Motif and Thyrotropin Receptor-Extracellular Domain Epitope Selection in Graves' Disease

    Science.gov (United States)

    Inaba, Hidefumi; Martin, William; Ardito, Matt; De Groot, Anne Searls; De Groot, Leslie J.

    2010-01-01

    Context: Development of Graves' disease (GD) is related to HLA-DRB1*0301 (DR3),and more specifically to arginine at position 74 of the DRB1 molecule. The extracellular domain (ECD) of human TSH receptor (hTSH-R) contains the target antigen. Objective and Design: We analyzed the relation between hTSH-R-ECD peptides and DR molecules to determine whether aspartic acid (D) or glutamic acid (E) at position four in the binding motif influenced selection of functional epitopes. Results: Peptide epitopes from TSH-R-ECD with D or E in position four (D/E+) had higher affinity for binding to DR3 than peptides without D/E (D/E−) (IC50 29.3 vs. 61.4, P = 0.0024). HLA-DR7, negatively correlated with GD, and DRB1*0302 (HLA-DR18), not associated with GD, had different profiles of epitope binding. Toxic GD patients who are DR3+ had higher responses to D/E+ peptides than D/E− peptides (stimulation index 1.42 vs. 1.22, P = 0.028). All DR3+ GD patients (toxic + euthyroid) had higher responses, with borderline significance (Sl; 1.32 vs. 1.18, P = 0.051). Splenocytes of DR3 transgenic mice immunized to TSH-R-ECD responded to D/E+ peptides more than D/E− peptides (stimulation index 1.95 vs. 1.69, P = 0.036). Seven of nine hTSH-R-ECD peptide epitopes reported to be reactive with GD patients' peripheral blood mononuclear cells contain binding motifs with D/E at position four. Conclusions: TSH-R-ECD epitopes with D/E in position four of the binding motif bind more strongly to DRB1*0301 than epitopes that are D/E− and are more stimulatory to GD patients' peripheral blood mononuclear cells and to splenocytes from mice immunized to hTSH-R. These epitopes appear important in immunogenicity to TSH-R due to their favored binding to HLA-DR3, thus increasing presentation to T cells. PMID:20392871

  18. Expression of N-methyl-D-aspartic acid 2A-B and 2B receptors in anterior thalamic nucleus and subiculum complex of rats

    Institute of Scientific and Technical Information of China (English)

    Yuanshan Fu; Xiaokai Ma; Xiaoling Yue; Bin Wang

    2008-01-01

    BACKGROUND: Glutamate acid ionotropic receptor N-methyl-D-aspartic acid (NMDA) takes part in long-term potentiation, thereby influencing the process of learning and memory.OBJECTIVE: To verify expression of NMDA 2A/B and 2B receptors in the anterior thalamic nucleus and subieulum complex of rats.DESIGN, TIME AND SETTING: A single-sample observation was performed at Department of Anatomy in Dalian Mcdical University (Dalian, Liaoning, China) from April to September in 2007.MATERIALS: Ten adult Wistar rats were used for this study, as well as rabbit anti-NMDA 2A/B and 2Bantibodies.METHODS: The rats were anesthetized and perfused, followed by brain resection and coronal sectioning of the brain tissue. A 1:3 series was selected for immunohistochemistry, using antibodies specific to NMDA 2A/B and 2B receptors. Photos were taken using the Nikon image analysis system.MAIN OUTCOME MEASURES: Expression and distribution of immunohistochemistry staining of NMDA 2A/B and 2B receptor subunits.RESULTS: There were a large number of NMDA 2A/B and 2B receptor-positive neurons distributed throughout the anterior dorsal thalamic nucleus. In the anterior ventral thalamic nucleus, distribution of positive neurons was rare, staining intensity was lighter, and cell bodies were smaller compared with the anterior dorsal thalamic nucleus. In the subiculum complex, staining intensity of NMDA 2A/B and 2B-positive neurons was weakest in the molecular layer and stronger in the pyramidal layer, in particular the region with large cell bodies adjacent to the molecular layer. In the multiform layer, more positive neurons of various sizes were detected.CONCLUSION: NMDA 2A/B and 2B receptor subunits were richly distributed in the anterior thalamic nucleus, with a small difference existing between the anterior dorsal nucleus and anterior ventral nucleus.These neurons were also differentially distributed within the three layers of the subiculum complex.

  19. Preparation of arginine–glycine–aspartic acid-modified biopolymeric nanoparticles containing epigalloccatechin-3-gallate for targeting vascular endothelial cells to inhibit corneal neovascularization

    Science.gov (United States)

    Chang, Che-Yi; Wang, Ming-Chen; Miyagawa, Takuya; Chen, Zhi-Yu; Lin, Feng-Huei; Chen, Ko-Hua; Liu, Guei-Sheung; Tseng, Ching-Li

    2017-01-01

    Neovascularization (NV) of the cornea can disrupt visual function, causing ocular diseases, including blindness. Therefore, treatment of corneal NV has a high public health impact. Epigalloccatechin-3-gallate (EGCG), presenting antiangiogenesis effects, was chosen as an inhibitor to treat human vascular endothelial cells for corneal NV treatment. An arginine–glycine–aspartic acid (RGD) peptide–hyaluronic acid (HA)-conjugated complex coating on the gelatin/EGCG self-assembly nanoparticles (GEH-RGD NPs) was synthesized for targeting the αvβ3 integrin on human umbilical vein endothelial cells (HUVECs) in this study, and a corneal NV mouse model was used to evaluate the therapeutic effect of this nanomedicine used as eyedrops. HA-RGD conjugation via COOH and amine groups was confirmed by 1H-nuclear magnetic resonance and Fourier-transform infrared spectroscopy. The average diameter of GEH-RGD NPs was 168.87±22.5 nm with positive charge (19.7±2 mV), with an EGCG-loading efficiency up to 95%. Images of GEH-RGD NPs acquired from transmission electron microscopy showed a spherical shape and shell structure of about 200 nm. A slow-release pattern was observed in the nanoformulation at about 30% after 30 hours. Surface plasmon resonance confirmed that GEH-RGD NPs specifically bound to the integrin αvβ3. In vitro cell-viability assay showed that GEH-RGD efficiently inhibited HUVEC proliferation at low EGCG concentrations (20 μg/mL) when compared with EGCG or non-RGD-modified NPs. Furthermore, GEH-RGD NPs significantly inhibited HUVEC migration down to 58%, lasting for 24 hours. In the corneal NV mouse model, fewer and thinner vessels were observed in the alkali-burned cornea after treatment with GEH-RGD NP eyedrops. Overall, this study indicates that GEH-RGD NPs were successfully developed and synthesized as an inhibitor of vascular endothelial cells with specific targeting capacity. Moreover, they can be used in eyedrops to inhibit angiogenesis in corneal NV

  20. Decreased Degradation of Internalized Follicle-Stimulating Hormone Caused by Mutation of Aspartic Acid 6.30550 in a Protein Kinase-CK2 Consensus Sequence in the Third Intracellular Loop of Human Follicle-Stimulating Hormone Receptor1

    Science.gov (United States)

    Kluetzman, Kerri S.; Thomas, Richard M.; Nechamen, Cheryl A.; Dias, James A.

    2011-01-01

    A naturally occurring mutation in follicle-stimulating hormone receptor (FSHR) gene has been reported: an amino acid change to glycine occurs at a conserved aspartic acid 550 (D550, D567, D6.30567). This residue is contained in a protein kinase-CK2 consensus site present in human FSHR (hFSHR) intracellular loop 3 (iL3). Because CK2 has been reported to play a role in trafficking of some receptors, the potential roles for CK2 and D550 in FSHR function were evaluated by generating a D550A mutation in the hFSHR. The hFSHR-D550A binds hormone similarly to WT-hFSHR when expressed in HEK293T cells. Western blot analyses showed lower levels of mature hFSHR-D550A. Maximal cAMP production of both hFSHR-D550A as well as the naturally occurring mutation hFSHR-D550G was diminished, but constitutive activity was not observed. Unexpectedly, when 125I-hFSH bound to hFSHR-D550A or hFSHR-D550G, intracellular accumulation of radiolabeled FSH was observed. Both sucrose and dominant-negative dynamin blocked internalization of radiolabeled FSH and its commensurate intracellular accumulation. Accumulation of radiolabeled FSH in cells transfected with hFSHR-D550A is due to a defect in degradation of hFSH as measured in pulse chase studies, and confocal microscopy imaging revealed that FSH accumulated in large intracellular structures. CK2 kinase activity is not required for proper degradation of internalized FSH because inhibition of CK2 kinase activity in cells expressing hFSHR did not uncouple degradation of internalized radiolabeled FSH. Additionally, the CK2 consensus site in FSHR iL3 is not required for binding because CK2alpha coimmunoprecipitated with hFSHR-D550A. Thus, mutation of D550 uncouples the link between internalization and degradation of hFSH. PMID:21270425

  1. Dataset of cocoa aspartic protease cleavage sites

    Directory of Open Access Journals (Sweden)

    Katharina Janek

    2016-09-01

    Full Text Available The data provide information in support of the research article, “The cleavage specificity of the aspartic protease of cocoa beans involved in the generation of the cocoa-specific aroma precursors” (Janek et al., 2016 [1]. Three different protein substrates were partially digested with the aspartic protease isolated from cocoa beans and commercial pepsin, respectively. The obtained peptide fragments were analyzed by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS/MS and identified using the MASCOT server. The N- and C-terminal ends of the peptide fragments were used to identify the corresponding in-vitro cleavage sites by comparison with the amino acid sequences of the substrate proteins. The same procedure was applied to identify the cleavage sites used by the cocoa aspartic protease during cocoa fermentation starting from the published amino acid sequences of oligopeptides isolated from fermented cocoa beans.

  2. A microalgae residue based carbon solid acid catalyst for biodiesel production.

    Science.gov (United States)

    Fu, Xiaobo; Li, Dianhong; Chen, Jie; Zhang, Yuanming; Huang, Weiya; Zhu, Yi; Yang, Jun; Zhang, Chengwu

    2013-10-01

    Biodiesel production from microalgae is recognized as one of the best solutions to deal with the energy crisis issues. However, after the oil extraction from the microalgae, the microalgae residue was generally discarded or burned. Here a novel carbon-based solid acid catalyst derived from microalgae residue by in situ hydrothermal partially carbonization were synthesized. The obtained catalyst was characterized and subjected to both the esterification of oleic acid and transesterification of triglyceride to produce biodiesel. The catalyst showed high catalytic activity and can be regenerated while its activity can be well maintained after five cycles.

  3. Effect of the secondary structure of carbohydrate residues of alpha 1-acid glycoprotein (orosomucoid) on the local dynamics of Trp residues.

    Science.gov (United States)

    Albani, Jihad René

    2004-01-01

    We studied in this work the relation between the secondary structure of the carbohydrate residues of alpha1-acid glycoprotein and the local motions of Trp residues of the protein. We measured for this purpose the fluorescence emission intensity and anisotropy of the Trp residues between -46 and +30 degrees of the sialylated and asialylated protein. Our results indicate that, in both forms, the global profile of the emission intensity with temperature shows that Trp residues display static and collisional interaction with the neighboring amino acids. However, the profile of the asialylated form is more structured than that observed for the sialylated protein. The Y-plot analysis of the emission-anisotropy results indicated that the frictional resistance to rotation of the surface Trp residue is less important in the sialylated protein than in the asialylated form. This result is in good agreement with the fact that, in the asialylated conformation, the carbohydrate residues are closer to the protein surface than in the sialylated form, thereby increasing the contact of the surface Trp residue with the neighboring amino acids. Also, the interaction between the carbohydrate residues and the surface Trp residue contributes to the modification of the frictional resistance to rotation of the fluorophore.

  4. Prazosin blocks the glutamatergic effects of N-methyl-D-aspartic acid on lordosis behavior and luteinizing hormone secretion in the estrogen-primed female rat

    Directory of Open Access Journals (Sweden)

    Landa A.I.

    2006-01-01

    Full Text Available We have observed that intracerebroventricular (icv injection of selective N-methyl-D-aspartic acid (NMDA-type glutamatergic receptor antagonists inhibits lordosis in ovariectomized (OVX, estrogen-primed rats receiving progesterone or luteinizing hormone-releasing hormone (LHRH. When NMDA was injected into OVX estrogen-primed rats, it induced a significant increase in lordosis. The interaction between LHRH and glutamate was previously explored by us and another groups. The noradrenergic systems have a functional role in the regulation of LHRH release. The purpose of the present study was to explore the interaction between glutamatergic and noradrenergic transmission. The action of prazosin, an alpha1- and alpha2b-noradrenergic antagonist, was studied here by injecting it icv (1.75 and 3.5 µg/6 µL prior to NMDA administration (1 µg/2 µL in OVX estrogen-primed Sprague-Dawley rats (240-270 g. Rats manually restrained were injected over a period of 2 min, and tested 1.5 h later. The enhancing effect induced by NMDA on the lordosis/mount ratio at high doses (67.06 ± 3.28, N = 28 when compared to saline controls (6 and 2 µL, 16.59 ± 3.20, N = 27 was abolished by prazosin administration (17.04 ± 5.52, N = 17, and 9.33 ± 3.21, N = 20, P < 0.001 for both doses. Plasma LH levels decreased significantly only with the higher dose of prazosin (1.99 ± 0.24 ng/mL, N = 18, compared to saline-NMDA effect, 5.96 ± 2.01 ng/mL, N = 13, P < 0.05. Behavioral effects seem to be more sensitive to the alpha-blockade than hormonal effects. These findings strongly suggest that the facilitatory effects of NMDA on both lordosis and LH secretion in this model are mediated by alpha-noradrenergic transmission.

  5. Un-catalyzed peptide bond formation between two monomers of glycine, alanine, serine, threonine, and aspartic acid in gas phase: a density functional theory study

    Science.gov (United States)

    Bhunia, Snehasis; Singh, Ajeet; Ojha, Animesh K.

    2016-05-01

    In the present report, un-catalyzed peptide bond formation between two monomers of glycine (Gly), alanine (Ala), serine (Ser), threonine (Thr), and aspartic acid (Asp) has been investigated in gas phase via two steps reaction mechanism and concerted mechanism at B3LYP/6-31G(d,p) and M062X/6-31G(d,p) level of theories. The peptide bond is formed through a nucleophilic reaction via transition states, TS1 and TS2 in stepwise mechanism. The TS1 reveals formation of a new C-N bond while TS2 illustrate the formation of C=O bond. In case of concerted mechanism, C-N bond is formed by a single four-centre transition state (TS3). The energy barrier is used to explain the involvement of energy at each step of the reaction. The energy barrier (20-48 kcal/mol) is required for the transformation of reactant state R1 to TS1 state and intermediate state I1 to TS2 state. The large value of energy barrier is explained in terms of distortion and interaction energies for stepwise mechanism. The energy barrier of TS3 in concerted mechanism is very close to the energy barrier of the first transition state (TS1) of the stepwise mechanism for the formation of Gly-Gly and Ala-Ala di- peptide. However, in case of Ser-Ser, Thr-Thr and Asp-Asp di-peptide, the energy barrier of TS3 is relatively high than that of the energy barrier of TS1 calculated at B3LYP/6-31G(d,p) and M062X/6-31G(d,p) level of theories. In both the mechanisms, the value of energy barrier calculated at B3LYP/6-31G(d,p) level of theory is greater than that of the value calculated at M062X/6-31G(d,p) level of theory.

  6. [Review of the psychiatric aspects of anti-NMDA (N-methyl-D-aspartic acid) receptor encephalitis, case report, and our plans for a future study].

    Science.gov (United States)

    Herman, Levente; Zsigmond, Ildiko Reka; Peter, Laszlo; Rethelyi, Janos M

    2016-12-01

    Anti-NMDAR (N-methyl-D-aspartic acid receptor) encephalitis, first described in 2007, is a rare, autoimmune limbic encephalitis. In half of the cases anti-NMDAR antibodies are paraneoplastic manifestations of an underlying tumor (mostly ovarian teratoma). In the early stage of the disease psychiatric symptoms are prominent, therefore 60-70% of the patients are first treated in a psychiatric department. In most of the cases, typical neurological symptoms appear later. Besides the clinical picture and typical symptoms, verifying presence of IgG antibodies in the serum or CSF is necessary to set up the diagnosis. Other diagnostic tools, including laboratory tests, MRI, lumbar puncture or EEG are neither specific, nor sensitive enough. Therapy is based on supportive care, plasma exchange and immune suppression, intensive care administration can be necessary. If there is an underlying tumor, tumor removal is the first-line treatment. The disease can cause fatal complications in the acute phase but with adequate therapy long-term prognosis is good, although rehabilitation can last for months. In the past few years besides the typical clinical picture and illness course an increasing number of case reports described no typical neurological symptoms, only psychiatric symptoms, including psychosis, disorganized behavior, and catatonic symptoms. Immune suppressive treatment was still effective in most of these cases. Such cases present a difficult diagnostic challenge. These patients may receive unnecessary antipsychotic treatment because of the suspected schizophrenia, although they often suffer from serious extrapyramidal side effects. A few years ago there was a hypothesis that a small part of the patients who are treated with therapy-resistant schizophrenia may suffer from anti-NMDAR encephalitis, so they require a different kind of medication. Evidence from the latest publications did not confirm this hypothesis, although the connection between anti-NMDAR antibodies and

  7. Optical imaging of head and neck squamous cell carcinoma in vivo using arginine-glycine- aspartic acid peptide conjugated near-infrared quantum dots

    Directory of Open Access Journals (Sweden)

    Huang H

    2013-12-01

    Full Text Available Hao Huang, Yun-Long Bai, Kai Yang, Hong Tang, You-Wei WangDepartment of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of ChinaAbstract: Molecular imaging plays a key role in personalized medicine and tumor diagnosis. Quantum dots with near-infrared emission spectra demonstrate excellent tissue penetration and photostability, and have recently emerged as important tools for in vivo tumor imaging. Integrin αvβ3 has been shown to be highly and specifically expressed in endothelial cells of tumor angiogenic vessels in almost all types of tumors, and specifically binds to the peptide containing arginine-glycine-aspartic acid (RGD. In this study, we conjugated RGD with quantum dots with emission wavelength of 800 nm (QD800 to generate QD800-RGD, and used it via intravenous injection as a probe to image tumors in nude mice bearing head and neck squamous cell carcinoma (HNSCC. Twelve hours after the injection, the mice were still alive and were sacrificed to isolate tumors and ten major organs for ex vivo analysis to localize the probe in these tissues. The results showed that QD800-RGD was specifically targeted to integrin αvβ3 in vitro and in vivo, producing clear tumor fluorescence images after the intravenous injection. The tumor-to-background ratio and size of tumor image were highest within 6 hours of the injection and declined significantly at 9 hours after the injection, but there was still a clearly visible tumor image at 12 hours. The greatest amount of QD800-RGD was found in liver and spleen, followed by tumor and lung, and a weak fluorescence signal was seen in tibia. No detectable signal of QD800-RGD was found in brain, heart, kidney, testis, stomach, or intestine. Our study demonstrated that using integrin αvβ3 as target, it is possible to use intravenously injected QD800-RGD to generate high quality images of HNSCC, and the technique offers great potential

  8. A multi-matrix HILIC-MS/MS method for the quantitation of endogenous small molecule neurological biomarker N-acetyl aspartic acid (NAA).

    Science.gov (United States)

    Sangaraju, Dewakar; Shahidi-Latham, Sheerin K; Burgess, Braydon L; Dean, Brian; Ding, Xiao

    2017-03-14

    A multi-matrix hydrophilic interaction liquid chromatography tandem mass spectrometric method (HILIC-MS/MS) was developed for the quantitation of N-Acetyl Aspartic acid (NAA) using stable isotope labeled internal standard, D3-NAA in various biological matrices such as human plasma, human CSF, mouse plasma, brain and spinal cord. A high throughput 96-well plate format supported liquid extraction (SLE) procedure was developed and used for sample preparation. Mass spectrometric analysis of NAA was performed using selected reaction monitoring transitions in positive electrospray ionization mode. As NAA is endogenously present, a surrogate matrix approach was used for quantitation of NAA and the method was qualified over linear calibration curve range of 0.01-10μg/mL. Intra and inter assay precision indicated by percent relative standard deviation (%RSD) was less than 7.1% for low, medium, medium high and high QCs. The accuracy of the method ranged from 92.6-107.0% of nominal concentration for within-run and between-run for the same QCs. Extraction recovery of NAA and D3-NAA was greater than 76%. Stability of NAA was established in the above biological matrices under bench top (RT, 5h), freeze thaw (-20±10°C, 3 cycles) and moues/human plasma sample collection (Wet ice, RT) conditions. HILIC-MS/MS method was then used to quantify and compare the NAA levels in human plasma and CSF of ALS patients versus control human subjects. NAA CSF levels in control human subjects (73.3±31.0ng/mL,N=10) were found to be slightly higher than ALS patients (46.1±22.6ng/mL, N=10) (P=0.04). No differences were observed in NAA plasma levels in human control subjects (49.7±13.8ng/mL,N=9) as compared to ALS patients (49.6±8.1ng/mL, N=10) (P=0.983). NAA endogenous concentrations in mouse plasma, brain and spinal cord were found to be 243.8±56.8ng/mL (N=6), 1029.8±115.2μg/g tissue weight (N=5) and 487.6±178.4μg/g tissue weight (N=5) respectively.

  9. Anti-N-methyl-D-aspartic acid receptor encephalitis: clinical analysis of 7 cases%抗NMDA受体脑炎七例临床分析

    Institute of Scientific and Technical Information of China (English)

    宋璐; 刘爱华

    2013-01-01

    目的 总结抗NMDA受体脑炎的临床及辅助检查的特点、提高对该病的认识.方法 分析2010年1月至2012年12月在宣武医院神经内科就诊的7例抗NMDA受体脑炎患者的临床特征、辅助检查,总结不同治疗方案的预后.结果 7例患者表现为显著的精神症状、癫痫、运动障碍,部分患者伴随自主神经功能异常,MRI显示边缘系统异常信号;CSF及血清NMDA受体抗体阳性,5例患者预后良好.结论 及时的诊断及治疗有助于抗NMDA受体脑炎患者的恢复.%Objective To summarize the clinical manifestations,immunotherapeutic response and prognosis of anti-N-methyl-D-aspartic acid (NMDA) receptor encephalitis.Methods We analyzed the clinical features,tumor markers,serum/cerebrospinal fluid (CSF) antibodies of seven cases with antiNMDA receptor encephalitis.And the prognosis of different treatments was observed.Results Seven patients presented with significant psychiatric symptoms,memory loss,epilepsy,movement disorders and decrease consciousness.And some patients required assisted ventilation because of dysautonomia.All electroencephalographs showed slow wave activity without epileptic form discharges.Magnetic resonance imaging was normal or showed T2W and Flair-phase high signal in limbic system,cortex,thalamus.And CSF and serum anti-NMDA receptor antibodieswere positive (n =6).Conclusion Anti-NMDA receptor encephalitis is a kind of fatal but treatable condition.And timely diagnosis and treatment may yield a favorable prognosis.

  10. Evolutionary diversification of aminopeptidase N in Lepidoptera by conserved clade-specific amino acid residues.

    Science.gov (United States)

    Hughes, Austin L

    2014-07-01

    Members of the aminopepidase N (APN) gene family of the insect order Lepidoptera (moths and butterflies) bind the naturally insecticidal Cry toxins produced by the bacterium Bacillus thuringiensis. Phylogenetic analysis of amino acid sequences of seven lepidopteran APN classes provided strong support for the hypothesis that lepidopteran APN2 class arose by gene duplication prior to the most recent common ancestor of Lepidoptera and Diptera. The Cry toxin-binding region (BR) of lepidopteran and dipteran APNs was subject to stronger purifying selection within APN classes than was the remainder of the molecule, reflecting conservation of catalytic site and adjoining residues within the BR. Of lepidopteran APN classes, APN2, APN6, and APN8 showed the strongest evidence of functional specialization, both in expression patterns and in the occurrence of conserved derived amino acid residues. The latter three APN classes also shared a convergently evolved conserved residue close to the catalytic site. APN8 showed a particularly strong tendency towards class-specific conserved residues, including one of the catalytic site residues in the BR and ten others in close vicinity to the catalytic site residues. The occurrence of class-specific sequences along with the conservation of enzymatic function is consistent with the hypothesis that the presence of Cry toxins in the environment has been a factor shaping the evolution of this multi-gene family.

  11. Preparation of arginine–glycine–aspartic acid-modified biopolymeric nanoparticles containing epigalloccatechin-3-gallate for targeting vascular endothelial cells to inhibit corneal neovascularization

    Directory of Open Access Journals (Sweden)

    Chang CY

    2016-12-01

    Full Text Available Che-Yi Chang,1,2,* Ming-Chen Wang,2,* Takuya Miyagawa,1 Zhi-Yu Chen,1 Feng-Huei Lin,3,4 Ko-Hua Chen,5,6 Guei-Sheung Liu,7 Ching-Li Tseng1 1Graduate Institute of Biomedical Materials and Tissue Engineering, College of Biomedical Engineering, Taipei Medical University, Taipei, 2Department of Biomedical Engineering, Chung Yuan Christian University, Taoyuan, 3Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan, 4Institute of Biomedical Engineering, National Taiwan University, 5Department of Ophthalmology, Taipei Veterans General Hospital, 6Department of Ophthalmology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; 7Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia *These authors contributed equally to this work Abstract: Neovascularization (NV of the cornea can disrupt visual function, causing ocular diseases, including blindness. Therefore, treatment of corneal NV has a high public health impact. Epigalloccatechin-3-gallate (EGCG, presenting antiangiogenesis effects, was chosen as an inhibitor to treat human vascular endothelial cells for corneal NV treatment. An arginine–glycine–aspartic acid (RGD peptide–hyaluronic acid (HA-conjugated complex coating on the gelatin/EGCG self-assembly nanoparticles (GEH-RGD NPs was synthesized for targeting the αvβ3 integrin on human umbilical vein endothelial cells (HUVECs in this study, and a corneal NV mouse model was used to evaluate the therapeutic effect of this nanomedicine used as eyedrops. HA-RGD conjugation via COOH and amine groups was confirmed by 1H-nuclear magnetic resonance and Fourier-transform infrared spectroscopy. The average diameter of GEH-RGD NPs was 168.87±22.5 nm with positive charge (19.7±2 mV, with an EGCG-loading efficiency up to 95%. Images of GEH-RGD NPs acquired from transmission electron microscopy showed a

  12. Mutagenesis and modeling of the peroxiredoxin (Prx) complex with the NMR structure of ATP-bound human sulfiredoxin implicate aspartate 187 of Prx I as the catalytic residue in ATP hydrolysis.

    Science.gov (United States)

    Lee, Duck-Yeon; Park, Sung Jun; Jeong, Woojin; Sung, Ho Jin; Oho, Taena; Wu, Xiongwu; Rhee, Sue Goo; Gruschus, James M

    2006-12-26

    The catalytic cysteine of certain members of the peroxiredoxin (Prx) family can be hyperoxidized to cysteinesulfinic acid during reduction of peroxides. Sulfiredoxin is responsible for the ATP-dependent reduction of cysteinesulfinic acid (SO2H) of hyperoxidized Prx. Here we report the NMR solution structure of human sulfiredoxin (hSrx), both with and without bound ATP, and we model the complex of ATP-bound hSrx with Prx. Binding ATP causes only small changes in the NMR structure of hSrx, and the bound ATP conformation is quite similar to that seen for the previously reported X-ray structure of the ADP-hSrx complex. Although hSrx binds ATP, it does not catalyze hydrolysis by itself and has no catalytic acid residue typical of most ATPase and kinase family proteins. For modeling the complex, the ATP-bound hSrx was docked to hyperoxidized Prx II using EMAP of CHARMM. In the model complex, Asn186 of Prx II (Asp187 of Prx I) is in contact with the hSrx-bound ATP beta- and gamma-phosphate groups. Asp187 of Prx I was mutated to alanine and asparagine, and binding and activity of the mutants with hSrx were compared to those of the wild type. For the D187N mutant, both binding and hydrolysis and reduction activities were comparable to those of the wild type, whereas for D187A, binding was unimpaired but ATP hydrolysis and reduction did not occur. The modeling and mutagenesis analyses strongly implicate Asp187 of Prx I as the catalytic residue responsible for ATP hydrolysis in the cysteinesulfinic acid reduction of Prx by hSrx.

  13. Isoelectric Point, Electric Charge, and Nomenclature of the Acid-Base Residues of Proteins

    Science.gov (United States)

    Maldonado, Andres A.; Ribeiro, Joao M.; Sillero, Antonio

    2010-01-01

    The main object of this work is to present the pedagogical usefulness of the theoretical methods, developed in this laboratory, for the determination of the isoelectric point (pI) and the net electric charge of proteins together with some comments on the naming of the acid-base residues of proteins. (Contains 8 figures and 4 tables.)

  14. Simultaneous analysis of D-alanine, D-aspartic acid, and D-serine using chiral high-performance liquid chromatography-tandem mass spectrometry and its application to the rat plasma and tissues.

    Science.gov (United States)

    Karakawa, Sachise; Shimbo, Kazutaka; Yamada, Naoyuki; Mizukoshi, Toshimi; Miyano, Hiroshi; Mita, Masashi; Lindner, Wolfgang; Hamase, Kenji

    2015-11-10

    A highly sensitive and selective chiral LC-MS/MS method for D-alanine, D-aspartic acid and D-serine has been developed using the precolumn derivatization reagents, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AccQ-Tag) or p-N,N,N-trimethylammonioanilyl N'-hydroxysuccinimidyl carbamate iodide (TAHS). The thus N-tagged enantiomers of the derivatized amino acids were nicely separated within 20min using the cinchona alkaloid-based zwittterionic ion-exchange type enantioselective column, Chiralpak ZWIX(+). The selected reaction monitoring was applied for detecting the target d-amino acids in biological matrices. By using the present chiral LC-MS/MS method, the three d-amino acids and their l-forms could be simultaneously determined in the range of 0.1-500nmol/mL. Finally, the technique was successfully applied to rat plasma and tissue samples.

  15. 生物医用类聚天冬氨酸衍生物的研究进展%Research on Biomedical Properties of Poly(aspartic acid) Derivatives

    Institute of Scientific and Technical Information of China (English)

    王晓娟; 逯彩彩; 伍国琳; 王亦农; 马建标

    2013-01-01

    Poly (amino acid) s have been extensively studied in biomedical applications, due to their excellent biocompatibility, biodegradability and various side groups for further functionalization. Poly (aspartic acid) can be synthesized by thermal polycondensation of L-aspartic acid, which is easily controlled and not costly. Its metabolites are non-toxic and would not produce toxic side effects to the surrounding tissue, liver, kidney, and red blood cells. It would be a good candidate for preparing polypeptide derivatives and was widely studied as the drug carriers, tissue engineering materials, etc. In this paper, research on poly (aspartic acid) s in the field of biomedical materials in recent years was reviewed, and mainly focused on the design and synthesis of poly (alpha, beta-L-aspartic acid) derivatives and their biomedical properties.%聚氨基酸类高分子材料因其良好的生物相容性、生物可吸收性及化学结构匹配性,在生物医用高分子领域有着无法比拟的优点和广泛的应用前景.特别是聚天冬氨酸,具有良好的生物相容性、生物降解性和可吸收性,合成方法简单,成本较低,易于功能化修饰等诸多优点.且在体内能够被逐渐吸收代谢,其代谢产物对人体无毒,不会对周围组织、肝肾、血红细胞等产生毒副作用.因此聚天冬氨酸及其衍生物,被广泛用于药物载体、组织工程等生物医药领域相关材料的制备研究.本文综述了近几年来聚天冬氨酸在生物医用高分子领域内的应用,重点介绍了聚(α,β-L-天冬氨酸)衍生物的设计合成及其生物医学性能.

  16. Ionic interaction of positive amino acid residues of fungal hydrophobin RolA with acidic amino acid residues of cutinase CutL1.

    Science.gov (United States)

    Takahashi, Toru; Tanaka, Takumi; Tsushima, Yusei; Muragaki, Kimihide; Uehara, Kenji; Takeuchi, Shunsuke; Maeda, Hiroshi; Yamagata, Youhei; Nakayama, Mayumi; Yoshimi, Akira; Abe, Keietsu

    2015-04-01

    Hydrophobins are amphipathic proteins secreted by filamentous fungi. When the industrial fungus Aspergillus oryzae is grown in a liquid medium containing the polyester polybutylene succinate co-adipate (PBSA), it produces RolA, a hydrophobin, and CutL1, a PBSA-degrading cutinase. Secreted RolA attaches to the surface of the PBSA particles and recruits CutL1, which then condenses on the particles and stimulates the hydrolysis of PBSA. Here, we identified amino acid residues that are required for the RolA-CutL1 interaction by using site-directed mutagenesis. We quantitatively analyzed kinetic profiles of the interactions between RolA variants and CutL1 variants by using a quartz crystal microbalance (QCM). The QCM analyses revealed that Asp142, Asp171 and Glu31, located on the hydrophilic molecular surface of CutL1, and His32 and Lys34, located in the N-terminus of RolA, play crucial roles in the RolA-CutL1 interaction via ionic interactions. RolA immobilized on a QCM electrode strongly interacted with CutL1 (K(D)  = 6.5 nM); however, RolA with CutL1 variants, or RolA variants with CutL1, showed markedly larger KD values, particularly in the interaction between the double variant RolA-H32S/K34S and the triple variant CutL1-E31S/D142S/D171S (K(D)  = 78.0 nM). We discuss a molecular prototype model of hydrophobin-based enzyme recruitment at the solid-water interface.

  17. Thorium aspartate tetrahydrate precursor to ThO2: Comparison of hydrothermal and thermal conversions

    Science.gov (United States)

    Clavier, N.; Maynadié, J.; Mesbah, A.; Hidalgo, J.; Lauwerier, R.; Nkou Bouala, G. I.; Parrès-Maynadié, S.; Meyer, D.; Dacheux, N.; Podor, R.

    2017-04-01

    The synthesis of original crystalline thorium aspartate tetrahydrate, Th(C4NO4H6)4.4H2O, was performed using two different wet-chemistry routes, involving either L-asparagine or L-aspartic acid as complexing agent. Characterization of this compound through 13C NMR and PXRD led to confirm the terminal coordination mode of the aspartate group and to suggest a potential cubic lattice (Pn-3 space group). Vibrational spectroscopy data were also collected. The conversion of thorium aspartate tetrahydrate into thorium dioxide was further performed through classical high temperature heat treatment or under hydrothermal conditions. On the one hand, thermal treatment provided a pseudomorphic conversion which retained the starting morphology, and favored the increase of the average crystallite size, as well as the complete elimination of the residual carbon content. On the other, hydrothermal conversion could be used to tune the morphology of the final oxide, ThO2.nH2O microspheres being prepared when starting from L-asparagine.

  18. Opposing effects of D-aspartic acid and nitric oxide on tuning of testosterone production in mallard testis during the reproductive cycle

    Directory of Open Access Journals (Sweden)

    Assisi Loredana

    2008-07-01

    Full Text Available Abstract Background D-Aspartic acid (D-Asp and nitric oxide (NO play an important role in tuning testosterone production in the gonads of male vertebrates. In particular, D-Asp promotes either the synthesis or the release of testosterone, whereas NO inhibits it. In this study, we have investigated for the first time in birds the putative effects of D-Asp and NO on testicular testosterone production in relation to two phases of the reproductive cycle of the adult captive wild-strain mallard (Anas platyrhynchos drake. It is a typical seasonal breeder and its cycle consists of a short reproductive period (RP in the spring (April-May and a non reproductive period (NRP in the summer (July, a time when the gonads are quiescent. The presence and the localization of D-Asp and NO in the testis and the trends of D-Asp, NO and testosterone levels were assessed during the main phases of the bird's reproductive cycle. Furthermore, in vitro experiments revealed the direct effect of exogenously administered D-Asp and NO on testosterone steroidogenesis. Methods By using immunohistochemical (IHC techniques, we studied the presence and the distributional pattern of D-Asp and NO in the testes of RP and NRP drakes. D-Asp levels were evaluated by an enzymatic method, whereas NO content, via nitrite, was assessed using biochemical measurements. Finally, immunoenzymatic techniques determined testicular testosterone levels. Results IHC analyses revealed the presence of D-Asp and NO in Leydig cells. The distributional pattern of both molecules was in some way correlated to the steroidogenic pathway, which is involved in autocrine testosterone production. Indeed, whereas NO was present only during the NRP, D-Asp was almost exclusively present during the RP. Consistently, the high testosterone testicular content occurring during RP was coupled to a high D-Asp level and a low NO content in the gonad. By contrast, in sexually inactive drakes (NRP, the low testosterone

  19. The cleavage specificity of the aspartic protease of cocoa beans involved in the generation of the cocoa-specific aroma precursors.

    Science.gov (United States)

    Janek, Katharina; Niewienda, Agathe; Wöstemeyer, Johannes; Voigt, Jürgen

    2016-11-15

    Particular peptides generated from the vicilin-class(7S) globulin of the cocoa beans by acid-induced proteolysis during cocoa fermentation are essential precursors of the cocoa-specific aroma notes. As revealed by in vitro studies, the formation of the cocoa-specific aroma precursors depends on the particular cleavage specificity of the cocoa aspartic protease, which cannot be substituted by pepsin. Therefore, we have investigated the effects of aspartic protease inhibitors on both enzymes and comparatively studied their cleavage specificities using different protein substrates and MALDI-TOF mass spectrometric analyses of the generated oligopeptides. Three classes of cleavage sites have been identified and characterized: (I) sequences exclusively cleaved by the cocoa enzyme, (II) sequences cleaved by both pepsin and the cocoa enzyme, and (III) those cleaved exclusively by pepsin. In contrast to most aspartic proteases from other origins, basic amino acid residues, particularly lysine, were found to be abundant in the specific cleavage sites of the cocoa enzyme.

  20. Residual mitochondrial transmembrane potential decreases unsaturated fatty acid level in sake yeast during alcoholic fermentation

    Directory of Open Access Journals (Sweden)

    Kazutaka Sawada

    2016-01-01

    Full Text Available Oxygen, a key nutrient in alcoholic fermentation, is rapidly depleted during this process. Several pathways of oxygen utilization have been reported in the yeast Saccharomyces cerevisiae during alcoholic fermentation, namely synthesis of unsaturated fatty acid, sterols and heme, and the mitochondrial electron transport chain. However, the interaction between these pathways has not been investigated. In this study, we showed that the major proportion of unsaturated fatty acids of ester-linked lipids in sake fermentation mash is derived from the sake yeast rather than from rice or koji (rice fermented with Aspergillus. Additionally, during alcoholic fermentation, inhibition of the residual mitochondrial activity of sake yeast increases the levels of unsaturated fatty acids of ester-linked lipids. These findings indicate that the residual activity of the mitochondrial electron transport chain reduces molecular oxygen levels and decreases the synthesis of unsaturated fatty acids, thereby increasing the synthesis of estery flavors by sake yeast. This is the first report of a novel link between residual mitochondrial transmembrane potential and the synthesis of unsaturated fatty acids by the brewery yeast during alcoholic fermentation.

  1. Residual mitochondrial transmembrane potential decreases unsaturated fatty acid level in sake yeast during alcoholic fermentation.

    Science.gov (United States)

    Sawada, Kazutaka; Kitagaki, Hiroshi

    2016-01-01

    Oxygen, a key nutrient in alcoholic fermentation, is rapidly depleted during this process. Several pathways of oxygen utilization have been reported in the yeast Saccharomyces cerevisiae during alcoholic fermentation, namely synthesis of unsaturated fatty acid, sterols and heme, and the mitochondrial electron transport chain. However, the interaction between these pathways has not been investigated. In this study, we showed that the major proportion of unsaturated fatty acids of ester-linked lipids in sake fermentation mash is derived from the sake yeast rather than from rice or koji (rice fermented with Aspergillus). Additionally, during alcoholic fermentation, inhibition of the residual mitochondrial activity of sake yeast increases the levels of unsaturated fatty acids of ester-linked lipids. These findings indicate that the residual activity of the mitochondrial electron transport chain reduces molecular oxygen levels and decreases the synthesis of unsaturated fatty acids, thereby increasing the synthesis of estery flavors by sake yeast. This is the first report of a novel link between residual mitochondrial transmembrane potential and the synthesis of unsaturated fatty acids by the brewery yeast during alcoholic fermentation.

  2. Oligo-aspartic acid conjugates with benzo[c][2,6]naphthyridine-8-carboxylic acid scaffold as picomolar inhibitors of CK2.

    Science.gov (United States)

    Vahter, Jürgen; Viht, Kaido; Uri, Asko; Enkvist, Erki

    2017-02-28

    Structurally diverse inhibitors of the protein kinase CK2 are required for regulation of this ubiquitous protein to establish biological roles of the enzyme which catalyzes the phosphorylation of a vast number of substrate proteins. In this article we disclose a series of new bisubstrate inhibitors of CK2 that are structurally represented by the oligo(l-Asp) peptide conjugates of benzo[c][2,6]naphthyridine-8-carboxylic acid. This fragment originated from CX-4945, the first in class inhibitor taken to clinical trials. The most potent conjugates possessed two-digit picomolar affinity and clear selectivity for CK2α in a panel of 140 protein kinases. Labeling of the inhibitors with a fluorescent dye yielded probes for a fluorescence anisotropy-based binding/displacement assay which can be used for analysis of CK2 and precise determination of affinity of the highly potent (tight-binding) CK2-targeting inhibitors.

  3. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The optimum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liquid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  4. Characteristics of lactic acid bacteria isolates and their effect on silage fermentation of fruit residues.

    Science.gov (United States)

    Yang, Jinsong; Tan, Haisheng; Cai, Yimin

    2016-07-01

    The natural lactic acid bacteria (LAB) population, chemical composition, and silage fermentation of fruit residues were studied. Eighty-two strains of LAB were isolated from fruit residues such as banana leaf and stem, pineapple peel, and papaya peel. All strains were gram-positive and catalase-negative bacteria, and they were divided into 7 groups (A-G) according to morphological and biochemical characters. Strains in groups A to F were rods, and group G was cocci. Group F produced gas from glucose; other groups did not. Groups A to C and F formed dl-lactic acid, whereas groups D, E, and G formed l-lactic acid. Based on the 16S rRNA gene sequence and DNA-DNA hybridization analysis, groups A to G strains were identified as Lactobacillus plantarum (54.9% of the total isolates), Lactobacillus paraplantarum (3.6%), Lactobacillus nagelii (8.5%), Lactobacillus perolens (4.9%), Lactobacillus casei (11.0%), Lactobacillus fermentum (9.8%), and Enterococcus gallinarum (7.3%), respectively. Lactobacillus plantarum and Lactobacillus casei are the most frequently isolated from fruit residues as a dominant species, and they could grow at a lower pH conditions and produce more lactic acid than other isolates. Pineapple and papaya peels contained higher crude protein (11.5-13.8%) and water-soluble carbohydrate (16.8-22.4%), but lower acid detergent fiber contents (21.2 to 26.4%) than banana stems and leaves (8.2% crude protein, 42.8% acid detergent fiber, and 5.1% water-soluble carbohydrate). Compared with banana stem and leaf silages, the pineapple and papaya peel silages were well preserved with a lower pH and higher lactate content. The study suggests that the fruit residues contain excellent LAB species and abundant feed nutrients, and that they can be preserved as silage to be potential food resources for livestock.

  5. Physicochemical pretreatments and hydrolysis of furfural residues via carbon-based sulfonated solid acid.

    Science.gov (United States)

    Ma, Bao Jun; Sun, Yuan; Lin, Ke Ying; Li, Bing; Liu, Wan Yi

    2014-03-01

    Potential commercial physicochemical pretreatment methods, NaOH/microwave and NaOH/ultrasound were developed, and the carbon-based sulfonated solid acid catalysts were prepared for furfural residues conversion into reducing sugars. After the two optimum pretreatments, both the content of cellulose increased (74.03%, 72.28%, respectively) and the content of hemicellulose (94.11%, 94.17% of removal rate, respectively) and lignin (91.75%, 92.09% of removal rate, respectively) decreased in furfural residues. The reducing sugar yields of furfural residues with the two physicochemical pretreatments on coal tar-based solid acid reached 33.94% and 33.13%, respectively, higher than that pretreated via NaOH alone (27%) and comparable to that pretreated via NaOH/H2O2 (35.67%). The XRD patterns, IR spectra and SEM images show microwave and ultrasound improve the pretreatment effect. The results demonstrate the carbon-based sulfonated solid acids and the physicochemical pretreatments are green, effective, low-cost for furfural residues conversion.

  6. Effect of Dodecylbenzene Sulfonic Acid Used as Additive on Residue Hydrotreating

    Institute of Scientific and Technical Information of China (English)

    Sun Yudong; Yang Chaohe

    2015-01-01

    The effect of additive—dodecylbenzene sulfonic acid (DBSA)—on residue hydrotreating was studied in the au-toclave. The results showed that the additive improved stabilization of the colloid system of residue, which could delay the aggregation and coke formation from asphaltenes on the catalyst, and make heavy components transformed into light oil. The residue conversion in the presence of this additive increased by 1.94%, and the yield of light oil increased by 1.53% when the reaction time was 90 min. The surface properties of the catalyst in the presence of this additive were better than that of the blank test within a very short time (30 min) and deteriorated rapidly after a longer reaction time due to higher conversion and coke deposition. Compared with the blank test, the case using the said additive had shown that the structure of hydrotreated asphaltene units was smaller and the condensation degrees were higher. The test results indicated that the additive could improve the hydrotreating reactivity of residue via permeation and depolymerization, the heavier components could be transformed into light oil more easily, and the light oil yield and residue conversion were higher for the case using the said additive in residue hydrotreating process.

  7. Identification of the amino acid residues rendering TI-VAMP insensitive toward botulinum neurotoxin B.

    Science.gov (United States)

    Sikorra, Stefan; Henke, Tina; Swaminathan, Subramanyam; Galli, Thierry; Binz, Thomas

    2006-03-24

    Botulinum neurotoxins types B, D, F, and G, and tetanus neurotoxin inhibit vesicular fusion via proteolytic cleavage of VAMP/Synaptobrevin, a core component of the membrane fusion machinery. Thus, these neurotoxins became widely used tools for investigating vesicular trafficking routes. Except for VAMP-1, VAMP-2, and Cellubrevin, no other member of the VAMP family represents a substrate for these neurotoxins. The molecular basis for this discrepancy is not known. A 34 amino acid residue segment of VAMP-2 was previously suggested to mediate the interaction with botulinum neurotoxin B, but the validity of the data was later questioned. To check whether this segment alone controls the susceptibility toward botulinum neurotoxin B, it was used to replace the corresponding segment in TI-VAMP. The resulting VAMP hybrid and VAMP-2 were hydrolysed at virtually identical rates. Resetting the VAMP-2 portion in the hybrid from either end to TI-VAMP residues gradually reduced the cleavability. A hybrid encompassing merely the VAMP-2 segment 71-80 around the Gln76/Phe77 scissile bond was still hydrolysed, albeit at a approximately tenfold lower cleavage rate. The contribution of each non-conserved amino acid of the whole 34-mer segment to the interaction was investigated employing VAMP-2. We find that the eight non-conserved residues of the 71-80 segment are all necessary for efficient cleavage. Mutation of an additional six residues located upstream and downstream of this segment affects substrate hydrolysis as well. Vice versa, a readily cleavable TI-VAMP molecule requires at the least the replacement of Ile158, Thr161, and the section 165-174 by Asp64, Ala67, and the 71-80 segment of VAMP-2, respectively. However, the insensitivity of TI-VAMP to botulinum neurotoxin B relies on at least 12 amino acid changes versus VAMP-2. These are scattered along an interface of 22 amino acid residues in length.

  8. R76 in transmembrane domain 3 of the aspartate:alanine transporter AspT is involved in substrate transport.

    Science.gov (United States)

    Suzuki, Satomi; Nanatani, Kei; Abe, Keietsu

    2016-01-01

    The L-aspartate:L-alanine antiporter of Tetragenococcus halophilus (AspT) possesses an arginine residue (R76) within the GxxxG motif in the central part of transmembrane domain 3 (TM3)-a residue that has been estimated to transport function. In this study, we carried out amino acid substitutions of R76 and used proteoliposome reconstitution for analyzing the transport function of each substitution. Both l-aspartate and l-alanine transport assays showed that R76K has higher activity than the AspT-WT (R76), whereas R76D and R76E have lower activity than the AspT-WT. These results suggest that R76 is involved in AspT substrate transport.

  9. Critical Amino Acid Residues for Nicotine 5' -Hydroxylation in Human CYP2A Enzymes

    Institute of Scientific and Technical Information of China (English)

    Xiaoyang He Xiaoyang He; Xu Xu; Jian Shen; Li Sun; Anthony Y. H. Lu; Clifford Weisel; Junyan Hong

    2008-01-01

    Objective: We have continued previous work in which we demonstrated that #117 and #372 amino acids contrib-uted to the high activities of human CYP2A13 in catalyzing 4-methylnitrosamino-1-(3-pyridyl)-1-hutanone(NNK) and aflatoxin B1(AFB1) carcinogenic activation. The present study was designed to identify other potential amino acid residues that contribute to the different catalytic characteristics of two CYP2A enzymes, CYP2A6 and CYP2A13, in nicotine metabolism and provide insights of the substrate and related amino acid residues interactions. Methods: A series of reciprocally substituted mutants of CYP2A6IIe'300→Phe, CYP2A6Gly'301Ala, CYP2A6Ser'369→Gly, CYP2A13Phe'300→Ile, CYP2A13AIa'301→Gly and CYP2A13Gly'369→Ser were generated by site-directed mutagenesis/baculovirus-Sf9 insect cells expression. Comparative kinetic analysis of nicotine 5'hydroxylatin by wild type and mutant CYP2A proteins was performed. Results:All amino acid residue substitutions at 300, 301 and 369 caused significant kinetic property changes in nicotine metabolism. While CYP2A6Ile'300→Phe and CYP2A6Gly'301→Ala mutations had notable catalytic efficiency increases compared to that for the wild type CYP2A6, CYP2A13Phe'300→Ile and CYP2A13Ala'301→Gly replacement introduced remarkable catalytic efficiency decreases. In addition, all these catalytic efficiency alterations were caused by V,maxvariations rather than K,m changes. Substi-tution of #369 residue significantly affected both K,m and V,max values. CYP2A6Ser'369→Gly increase the catalytic efficiency via a significant Km decrease versus V,max enhancement, while the opposite effects were seen with CYP2A13Gly'369→Ser. Conclusion:#300, #301 and #369 residues in human CYP2A6/13 play important roles in nicotine 5' -oxidation. Switching #300 or #301 residues did not affect the CYP2A protein affinities toward nicotine, although these amino acids are located in the active center. Seta69 to Gly substitution indirectly affected

  10. The sodium effect of Bacillus subtilis growth on aspartate.

    Science.gov (United States)

    Whiteman, P; Marks, C; Freese, E

    1980-08-01

    aspH mutants of Bacillus subtilis have a constitutive aspartase activity and grow well on aspartate as sole carbon source. aspH aspT mutants, which are deficient in high affinity aspartate transport as a result of the aspT mutation, grow as well as aspH mutants in medium containing high concentrations of aspartate and Na+. This Na+ effect is not due to an enhancement of aspartate transport but is the result of increased cellular metabolism. The ability to grow rapidly in sodium aspartate is induced by prior growth in the presence of Na+. In potassium aspartate, the addition of arginine, citrulline, ornithine, delta 1-pyrroline-5-carboxylase or proline instead of Na+ also allows rapid growth; but in a mutant deficient in ornithine--oxo-acid aminotransferase, only pyrroline-carboxylate or proline can replace Na+. The amino acid pool of cells growing slowly in potassium aspartate contains proline at a low concentration which increases upon addition of proline (but not Na+) to the medium. Thus, Na+ addition does not increase the synthesis of proline, but proline or pyrroline-carboxylate acts similarly to Na+ either in preventing some inhibitory effect (by aspartate or the accumulating NH4+) or in overcoming some deficiency (e.g. in further proline metabolism.

  11. Site-directed mutagenesis of amino acid residues of D1 protein interacting with phosphatidylglycerol affects the function of plastoquinone QB in photosystem II.

    Science.gov (United States)

    Endo, Kaichiro; Mizusawa, Naoki; Shen, Jian-Ren; Yamada, Masato; Tomo, Tatsuya; Komatsu, Hirohisa; Kobayashi, Masami; Kobayashi, Koichi; Wada, Hajime

    2015-12-01

    Recent X-ray crystallographic analysis of photosystem (PS) II at 1.9-Å resolution identified 20 lipid molecules in the complex, five of which are phosphatidylglycerol (PG). In this study, we mutagenized amino acid residues S232 and N234 of D1, which interact with two of the PG molecules (PG664 and PG694), by site-directed mutagenesis in Synechocystis sp. PCC 6803 to investigate the role of the interaction in PSII. The serine and asparagine residues at positions 232 and 234 from the N-terminus were mutagenized to alanine and aspartic acid, respectively, and a mutant carrying both amino acid substitutions was also produced. Although the obtained mutants, S232A, N234D, and S232AN234D, exhibited normal growth, they showed decreased photosynthetic activities and slower electron transport from QA to QB than the control strain. Thermoluminescence analysis suggested that this slower electron transfer in the mutants was caused by more negative redox potential of QB, but not in those of QA and S2. In addition, the levels of extrinsic proteins, PsbV and PsbU, were decreased in PSII monomer purified from the S232AN234D mutant, while that of Psb28 was increased. In the S232AN234D mutant, the content of PG in PSII was slightly decreased, whereas that of monogalactosyldiacylglycerol was increased compared with the control strain. These results suggest that the interactions of S232 and N234 with PG664 and PG694 are important to maintain the function of QB and to stabilize the binding of extrinsic proteins to PSII.

  12. Relation between the secondary structure of carbohydrate residues of alpha1-acid glycoprotein (orosomucoid) and the fluorescence of the protein.

    Science.gov (United States)

    Albani, Jihad R

    2003-05-01

    We studied in this work the relation that exists between the secondary structure of the glycans of alpha(1)-acid glycoprotein and the fluorescence of the Trp residues of the protein. We calculated for that the efficiency of quenching and the radiative and non-radiative constants. Our results indicate that the glycans display a spatial structure that is modified upon asialylation. The asialylated conformation is closer to the protein matrix than the sialylated form, inducing by that a decrease in the fluorescence parameters of the Trp residues. In fact, the mean quantum yield of Trp residues in sialylated and asialylated alpha(1)-acid glycoprotein are 0.0645 and 0.0385, respectively. Analysis of the fluorescence emission of alpha(1)-acid glycoprotein as the result of two contributions (surface and hydrophobic domains) indicates that quantum yields of both classes of Trp residues are lower when the protein is in the asialylated form. Also, the mean fluorescence lifetime of Trp residues decreases from 2.285 ns in the sialylated protein to 1.948 ns in the asialylated one. The radiative rate constant k(r) of the Trp residues in the sialylated alpha(1)-acid glycoprotein is higher than that in the asialylated protein. Thus, the carbohydrate residues are closer to the Trp residues in the absence of sialic acid. The modification of the spatial conformation of the glycans upon asialylation is confirmed by the decrease of the fluorescence lifetimes of Calcofluor, a fluorophore that binds to the carbohydrate residues. Finally, thermal intensity quenching of Calcofluor bound to alpha(1)-acid glycoprotein shows that the carbohydrate residues have slower residual motions in the absence of sialic acid residues.

  13. Natural populations of lactic acid bacteria isolated from vegetable residues and silage fermentation.

    Science.gov (United States)

    Yang, J; Cao, Y; Cai, Y; Terada, F

    2010-07-01

    Natural populations of lactic acid bacteria (LAB) and silage fermentation of vegetable residues were studied. Fifty-two strains of LAB isolated from cabbage, Chinese cabbage, and lettuce residues were identified and characterized. The LAB strains were gram-positive and catalase-negative bacteria, which were divided into 6 groups (A to F) according to morphological and biochemical characteristics. The strains in group A were rods that did not produce gas from glucose and formed the d and l isomers of lactate. Groups B and C were homofermentative cocci that formed l-lactic acid. Groups D, E, and F were heterofermentative cocci that formed d-lactic acid. Based on 16S rDNA gene sequence analysis, group A to F strains were identified as Lactobacillus plantarum, Lactococcus piscium, Lactococcus lactis, Leuconostoc citreum, Weissella soli and Leuconostoc gelidum, respectively. The prevalent LAB, predominantly homofermentative lactobacilli, consisted of Lactobacillus plantarum (34.6%), Weissella soli (19.2%), Leuconostoc gelidum (15.4%), Leuconostoc citreum (13.5%), Lactococcus lactis (9.6%), and Lactococcus piscium (7.7%). Lactobacillus plantarum was the dominant member of the LAB population in 3 types of vegetable residues. These vegetable residues contained a high level of crude protein (20.2 to 28.4% of dry matter). These silages prepared by using a small-scale fermentation system were well preserved, with low pH and a relatively high content of lactate. This study suggests that the vegetable residues contain abundant LAB species and nutrients, and that they could be well preserved by making silage, which is a potentially good vegetable protein source for livestock diets.

  14. Comparison between liquid and solid acids catalysts on reducing sugars conversion from furfural residues via pretreatments.

    Science.gov (United States)

    Lin, Keying; Ma, Baojun; Sun, Yuan; Liu, Wanyi

    2014-09-01

    Liquid sulphuric acid is adopted and compared with carbon-based sulfonated solid acids (coal tar-based and active carbon-based) for furfural residues conversion into reducing sugars. The optimum hydrolysis conditions of liquid acid are at 4% of sulphuric acid, 25:1 of liquid and solid ratio, 175°C of reaction temperature and 120 min of reaction time. The reducing sugar yields are reached over 60% on liquid acid via NaOH/H2O2, NaOH/microwave and NaOH/ultrasonic pretreatments, whereas only over 30% on solid acids. The TOFs (turnover number frequency) via NaOH/H2O2 pretreatments are 0.093, 0.020 and 0.023 h(-1) for liquid sulphuric acid, coal tar-based and active carbon-based solid acids catalysts, respectively. Considering the efficiency, cost and environment factors, the liquid and solid acids have their own advantages of potential commercial application values.

  15. [Aspartate kinase from the cyanobacteriium Plectonema boryanum infected with the cyanophage LPP-3].

    Science.gov (United States)

    Perepelitsa, S I; Koltukova, N V; Mendzhul, M I

    1995-01-01

    The effect of development of cyanophage infection on the activity of aspartate kinase of Plectonema boryanum has been studied. It has been determined that activity of aspartate kinase increased during early period of reproduction of cyanophage. It coincided in time with the increase of the level of amino acids of aspartate family. Isoenzymes of aspartate kinase were isolated from the infected cells purified and studied. Expression of viral genome is accompanied with the appearance of four new isoenzymes determined by virus. The revealed aspartate kinases are not subject of regulation by amino acids (the end-products of biosynthesis) according to the principle of feed-back inhibition.

  16. Lactobacillus plantarum BL011 cultivation in industrial isolated soybean protein acid residue

    Directory of Open Access Journals (Sweden)

    Chaline Caren Coghetto

    Full Text Available Abstract In this study, physiological aspects of Lactobacillus plantarum BL011 growing in a new, all-animal free medium in bioreactors were evaluated aiming at the production of this important lactic acid bacterium. Cultivations were performed in submerged batch bioreactors using the Plackett-Burman methodology to evaluate the influence of temperature, aeration rate and stirring speed as well as the concentrations of liquid acid protein residue of soybean, soy peptone, corn steep liquor, and raw yeast extract. The results showed that all variables, except for corn steep liquor, significantly influenced biomass production. The best condition was applied to bioreactor cultures, which produced a maximal biomass of 17.87 g L-1, whereas lactic acid, the most important lactic acid bacteria metabolite, peaked at 37.59 g L-1, corresponding to a productivity of 1.46 g L-1 h-1. This is the first report on the use of liquid acid protein residue of soybean medium for L. plantarum growth. These results support the industrial use of this system as an alternative to produce probiotics without animal-derived ingredients to obtain high biomass concentrations in batch bioreactors.

  17. Lactobacillus plantarum BL011 cultivation in industrial isolated soybean protein acid residue.

    Science.gov (United States)

    Coghetto, Chaline Caren; Vasconcelos, Carolina Bettker; Brinques, Graziela Brusch; Ayub, Marco Antônio Záchia

    In this study, physiological aspects of Lactobacillus plantarum BL011 growing in a new, all-animal free medium in bioreactors were evaluated aiming at the production of this important lactic acid bacterium. Cultivations were performed in submerged batch bioreactors using the Plackett-Burman methodology to evaluate the influence of temperature, aeration rate and stirring speed as well as the concentrations of liquid acid protein residue of soybean, soy peptone, corn steep liquor, and raw yeast extract. The results showed that all variables, except for corn steep liquor, significantly influenced biomass production. The best condition was applied to bioreactor cultures, which produced a maximal biomass of 17.87gL(-1), whereas lactic acid, the most important lactic acid bacteria metabolite, peaked at 37.59gL(-1), corresponding to a productivity of 1.46gL(-1)h(-1). This is the first report on the use of liquid acid protein residue of soybean medium for L. plantarum growth. These results support the industrial use of this system as an alternative to produce probiotics without animal-derived ingredients to obtain high biomass concentrations in batch bioreactors.

  18. A method for computing the inter-residue interaction potentials for reduced amino acid alphabet

    Indian Academy of Sciences (India)

    Abhinav Luthra; Anupam Nath Jha; G K Ananthasuresh; Saraswathi Vishveswara

    2007-08-01

    Inter-residue potentials are extensively used in the design and evaluation of protein structures. However, dealing with all (20×20) interactions becomes computationally difficult in extensive investigations. Hence, it is desirable to reduce the alphabet of 20 amino acids to a smaller number. Currently, several methods of reducing the residue types exist; however a critical assessment of these methods is not available. Towards this goal, here we review and evaluate different methods by comparing with the complete (20×20) matrix of Miyazawa-Jernigan potential, including a method of grouping adopted by us, based on multi dimensional scaling (MDS). The second goal of this paper is the computation of inter-residue interaction energies for the reduced amino acid alphabet, which has not been explicitly addressed in the literature until now. By using a least squares technique, we present a systematic method of obtaining the interaction energy values for any type of grouping scheme that reduces the amino acid alphabet. This can be valuable in designing the protein structures.

  19. Nanoparticle carriers based on copolymers of poly( l-aspartic acid co- l-lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine for drug delivery

    Science.gov (United States)

    Han, Siyuan; Wang, Huan; Liang, Xingjie; Hu, Liming; Li, Min; Wu, Yan

    2011-09-01

    A novel poly( l-aspartic) derivative (PAL-DPPE) containing polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments has been successfully synthesized. The chemical structures of the copolymers were confirmed by Fourier-transform infrared spectroscopy (FTIR), NMR (1H NMR, 13C NMR, 31P NMR), and thermogravimetric analysis (TGA). Fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) confirmed the formation of micelles of the PAL-DPPE copolymers. In order to estimate the feasibility as novel drug carriers, an anti-tumor model drug doxorubicin (DOX) was incorporated into polymeric micelles by double emulsion and nanoprecipitation method. The DOX-loaded micelle size, size distribution, and encapsulation efficiency (EE) were influenced by the feed weight ratio of the copolymer to DOX. In addition, in vitro release experiments of the DOX-loaded PAL-DPPE micelles exhibited that faster release in pH 5.0 than their release in pH 7.4 buffer. The poly( l-aspartic) derivative copolymer was proved to be an available carrier for the preparation of micelles for anti-tumor drug delivery.

  20. Nanoparticle carriers based on copolymers of poly(l-aspartic acid co-l-lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Han Siyuan; Wang Huan; Liang Xingjie [National Center for Nanoscience and Technology, Laboratory of Nanobiomedicine and Nanosafety, Division of Nanomedicine and Nanobiology (China); Hu Liming, E-mail: huliming@bjut.edu.cn [Beijing University of Technology, College of Life Science and Bioengineering (China); Li Min; Wu Yan, E-mail: wuy@nanoctr.cn [National Center for Nanoscience and Technology, Laboratory of Nanobiomedicine and Nanosafety, Division of Nanomedicine and Nanobiology (China)

    2011-09-15

    A novel poly(l-aspartic) derivative (PAL-DPPE) containing polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments has been successfully synthesized. The chemical structures of the copolymers were confirmed by Fourier-transform infrared spectroscopy (FTIR), NMR ({sup 1}H NMR, {sup 13}C NMR, {sup 31}P NMR), and thermogravimetric analysis (TGA). Fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) confirmed the formation of micelles of the PAL-DPPE copolymers. In order to estimate the feasibility as novel drug carriers, an anti-tumor model drug doxorubicin (DOX) was incorporated into polymeric micelles by double emulsion and nanoprecipitation method. The DOX-loaded micelle size, size distribution, and encapsulation efficiency (EE) were influenced by the feed weight ratio of the copolymer to DOX. In addition, in vitro release experiments of the DOX-loaded PAL-DPPE micelles exhibited that faster release in pH 5.0 than their release in pH 7.4 buffer. The poly(l-aspartic) derivative copolymer was proved to be an available carrier for the preparation of micelles for anti-tumor drug delivery.

  1. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    DU GaoXiang; ZHENG ShuiLin; DING Hao

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The op-timum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liq-uid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  2. Biochemical Roles for Conserved Residues in the Bacterial Fatty Acid-binding Protein Family.

    Science.gov (United States)

    Broussard, Tyler C; Miller, Darcie J; Jackson, Pamela; Nourse, Amanda; White, Stephen W; Rock, Charles O

    2016-03-18

    Fatty acid kinase (Fak) is a ubiquitous Gram-positive bacterial enzyme consisting of an ATP-binding protein (FakA) that phosphorylates the fatty acid bound to FakB. In Staphylococcus aureus, Fak is a global regulator of virulence factor transcription and is essential for the activation of exogenous fatty acids for incorporation into phospholipids. The 1.2-Å x-ray structure of S. aureus FakB2, activity assays, solution studies, site-directed mutagenesis, and in vivo complementation were used to define the functions of the five conserved residues that define the FakB protein family (Pfam02645). The fatty acid tail is buried within the protein, and the exposed carboxyl group is bound by a Ser-93-fatty acid carboxyl-Thr-61-His-266 hydrogen bond network. The guanidinium of the invariant Arg-170 is positioned to potentially interact with a bound acylphosphate. The reduced thermal denaturation temperatures of the T61A, S93A, and H266A FakB2 mutants illustrate the importance of the hydrogen bond network in protein stability. The FakB2 T61A, S93A, and H266A mutants are 1000-fold less active in the Fak assay, and the R170A mutant is completely inactive. All FakB2 mutants form FakA(FakB2)2 complexes except FakB2(R202A), which is deficient in FakA binding. Allelic replacement shows that strains expressing FakB2 mutants are defective in fatty acid incorporation into phospholipids and virulence gene transcription. These conserved residues are likely to perform the same critical functions in all bacterial fatty acid-binding proteins.

  3. Leaching of lead from zinc leach residue in acidic calcium chloride aqueous solution

    Science.gov (United States)

    Wang, Le; Mu, Wen-ning; Shen, Hong-tao; Liu, Shao-ming; Zhai, Yu-chun

    2015-05-01

    A process with potentially reduced environmental impacts and occupational hazards of lead-bearing zinc plant residue was studied to achieve a higher recovery of lead via a cost-effective and environmentally friendly process. This paper describes an optimization study on the leaching of lead from zinc leach residue using acidic calcium chloride aqueous solution. Six main process conditions, i.e., the solution pH value, stirring rate, concentration of CaCl2 aqueous solution, liquid-to-solid (L/S) ratio, leaching temperature, and leaching time, were investigated. The microstructure and components of the residue and tailing were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). On the basis of experimental results, the optimum reaction conditions were determined to be a solution pH value of 1, a stirring rate of 500 r·min-1, a CaCl2 aqueous solution concentration of 400 g·L-1, a liquid-to-solid mass ratio of 7:1, a leaching temperature of 80°C, and a leaching time of 45 min. The leaching rate of lead under these conditions reached 93.79%, with an iron dissolution rate of 19.28%. Silica did not take part in the chemical reaction during the leaching process and was accumulated in the residue.

  4. [Determination of clavulanic acid residue in milk by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Yang, Gang; Huang, Xianhui; Guo, Chunna; Fang, Qiuhua; He, Limin

    2012-06-01

    An analytical method was developed for the determination of clavulanic acid (CLAV) in milk by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A 2 g milk sample was deproteinized by ethanol. The supernatant was transferred into a pear-shaped bottle to be evaporated to about 0.5 mL, and the residue was dissolved with ammonium acetate solution. The sample was determined by HPLC-MS/MS after the purification. The chromatographic separation was achieved on a Luna 5u C8 column using 0.1% formic acid in water and acetonitrile as mobile phases with gradient elution. The identification of CLAV was carried out by MS/MS equipped with electrospray ionization in negative scanning and multiple reaction monitoring (MRM) modes. Matrix-matched calibration standard was used for the quantification. The calibration curve showed perfect linear in the range of 10 - 400 microg/kg with the correlation coefficient of 0.999. The limit of detection (LOD, S/N > or = 3) was 10 microg/kg in milk, and the limit of quantification (LOQ, S/N > or = 10) was 20 microg/kg. The mean recoveries varied from 80.00% to 91.25% at the four spiked levels of LOQ, 1/2MRL (the maximum residue limit), MRL, and 2MRL with the relative standard deviations of 5.60% -8.77%. In conclusion, the established method can be applied for the determination of CLAV residues in milk.

  5. Composition, texture and methane potential of cellulosic residues from Lewis acids organosolv pulping of wheat straw.

    Science.gov (United States)

    Constant, Sandra; Barakat, Abdellatif; Robitzer, Mike; Di Renzo, Francesco; Dumas, Claire; Quignard, Françoise

    2016-09-01

    Cellulosic pulps have been successfully isolated from wheat straw through a Lewis acids organosolv treatment. The use of Lewis acids with different hardness produced pulps with different delignification degrees. The cellulosic residue was characterised by chemical composition, X-ray diffraction, FT-IR spectroscopy, N2 physisorption, scanning electron microscopy and potential for anaerobic digestibility. Surface area and pore volume increased with the hardness of the Lewis acid, in correspondence with the decrease of the amount of lignin and hemicellulose in the pulp. The non linearity of the correlation between porosity and composition suggests that an agglomeration of cellulose fibrils occurs in the early stages of pulping. All organosolv pulps presented a significantly higher methane potential than the parent straw. A methane evolution of 295Ncm(3)/g OM was reached by a moderate improvement of the accessibility of the native straw.

  6. Mutation-induced quisqualic acid and ibotenic acid affinity at the metabotropic glutamate receptor subtype 4: ligand selectivity results from a synergy of several amino acid residues

    DEFF Research Database (Denmark)

    Hermit, Mette B; Greenwood, Jeremy R; Bräuner-Osborne, Hans

    2004-01-01

    resides. In this study, we have identified four non-conserved amino acid residues that are essential for differentiating mGluR1 from mGluR4. Our approach has been to increase the affinity of the classic mGluR1 agonists, quisqualic acid and ibotenic acid, at mGluR4 by making various point mutations...... that mimicked mGluR1 residues. Based on ligand docking to homology models, the non-conserved residues, Lys-74, Glu-287, Ser-313, and Lys-317, were chosen for the mutational studies and all of the mutations proved capable of partially or completely restoring the affinities of the ligands. In particular......, the mutations K74Y and K317R induced dramatic triple-order-of-magnitude increases in the affinity of ibotenic acid at mGluR4, making the affinity equivalent to that of mGluR1. Furthermore, the affinity of quisqualic acid at mGluR4 was increased to the same level as mGluR1 by the two double mutations, K74Y/K317R...

  7. Acid hydrolysis of Curcuma longa residue for ethanol and lactic acid fermentation.

    Science.gov (United States)

    Nguyen, Cuong Mai; Nguyen, Thanh Ngoc; Choi, Gyung Ja; Choi, Yong Ho; Jang, Kyoung Soo; Park, Youn-Je; Kim, Jin-Cheol

    2014-01-01

    This research examines the acid hydrolysis of Curcuma longa waste, to obtain the hydrolysate containing lactic acid and ethanol fermentative sugars. A central composite design for describing regression equations of variables was used. The selected optimum condition was 4.91% sulphuric acid, 122.68°C and 50 min using the desirability function under the following conditions: the maximum reducing sugar (RS) yield is within the limited range of the 5-hydroxymethylfurfural (HMF) and furfural concentrations. Under the condition, the obtained solution contained 144 g RS/L, 0.79 g furfural/L and 2.59 g HMF/L and was directly fermented without a detoxification step. The maximum product concentration, average productivity, RS conversion and product yield were 115.36 g/L, 2.88 g/L/h, 89.43% and 64% for L-lactic acid; 113.92 g/L, 2.59 g/L/h, 88.31% and 63.29% for D-lactic acid; and 55.03 g/L, 1.38 g/L/h, 42.66 and 30.57%, respectively, for ethanol using a 7-L jar fermenter.

  8. Chemical modification of amino acid residues in glycerinated Vorticella stalk and Ca(2+)-induced contractility.

    Science.gov (United States)

    Kono, R; Ochiai, T; Asai, H

    1997-01-01

    The glycerinated stalk of the peritrich ciliate Vorticella, was treated with various reagents to chemically modify the amino acid residues. The influences of these modifcations on spasmoneme contractility were investigated. First, it was confirmed that the spasmoneme contraction is not inhibited by alteration of SH groups. It was also demonstrated that chemical modification of methionine and tryptophan residues abolishes spasmoneme contractility. The reagents used for chemical modification were N-bromosuccinimide (NBS), chloramine T, and 2-hydroxy-5-nitrobenzyl bromide (HNBB), which abolished spasmoneme contractility at concentrations of 40-50 microM, 200-300 microM, and 4 mM, respectively. These results suggest that, along with Ca2+ binding proteins, there are other as yet to be identified proteins involved in contractility.

  9. Contributions of a Position Amino Acid Residues to the Conformational Stability of GCN4 Leucine Zipper

    Institute of Scientific and Technical Information of China (English)

    WEI Xiang; ZENG Xian'gang; ZHOU Haimeng

    2006-01-01

    The stability of GCN4 leucine zipper and its four mutants in guanidine hydrochloride was detected to verify the contributions of different a position amino acid residues in polypeptide sequences to the forming and stability of parallel coiled coils. The changes of the circular dichroism spectra show that the displacement of the a position polar asparagine and the increase of asparagine in the GCN4 leucine zipper can reduce the α-helix content of the coiled coil structure. The mutants are less stable than the natural peptide in guanidine hydrochloride. The results show that the interaction between the polar asparagine contributes to the conformational stability of the coiled coil. Both the conformation and the number of polar residues in the coiled coil also affect the α-helix content and its resistance to the denaturant. The conclusions provide evidence describing the folding process of proteins including coiled coils in vivo.

  10. Substitution at Aspartic Acid 1128 in the SARS Coronavirus Spike Glycoprotein Mediates Escape from a S2 Domain-Targeting Neutralizing Monoclonal Antibody

    Science.gov (United States)

    Ng, Oi-Wing; Keng, Choong-Tat; Leung, Cynthia Sau-Wai; Peiris, J. S. Malik; Poon, Leo Lit Man; Tan, Yee-Joo

    2014-01-01

    The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) is the etiological agent for the infectious disease, SARS, which first emerged 10 years ago. SARS-CoV is a zoonotic virus that has crossed the species barriers to infect humans. Bats, which harbour a diverse pool of SARS-like CoVs (SL-CoVs), are believed to be the natural reservoir. The SARS-CoV surface Spike (S) protein is a major antigenic determinant in eliciting neutralizing antibody production during SARS-CoV infection. In our previous work, we showed that a panel of murine monoclonal antibodies (mAbs) that target the S2 subunit of the S protein are capable of neutralizing SARS-CoV infection in vitro (Lip KM et al, J Virol. 2006 Jan; 80(2): 941–50). In this study, we report our findings on the characterization of one of these mAbs, known as 1A9, which binds to the S protein at a novel epitope within the S2 subunit at amino acids 1111–1130. MAb 1A9 is a broadly neutralizing mAb that prevents viral entry mediated by the S proteins of human and civet SARS-CoVs as well as bat SL-CoVs. By generating mutant SARS-CoV that escapes the neutralization by mAb 1A9, the residue D1128 in S was found to be crucial for its interaction with mAb 1A9. S protein containing the substitution of D1128 with alanine (D1128A) exhibited a significant decrease in binding capability to mAb 1A9 compared to wild-type S protein. By using a pseudotyped viral entry assay, it was shown that the D1128A substitution in the escape virus allows it to overcome the viral entry blockage by mAb 1A9. In addition, the D1128A mutation was found to exert no effects on the S protein cell surface expression and incorporation into virion particles, suggesting that the escape virus retains the same viral entry property as the wild-type virus. PMID:25019613

  11. Substitution at aspartic acid 1128 in the SARS coronavirus spike glycoprotein mediates escape from a S2 domain-targeting neutralizing monoclonal antibody.

    Directory of Open Access Journals (Sweden)

    Oi-Wing Ng

    Full Text Available The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV is the etiological agent for the infectious disease, SARS, which first emerged 10 years ago. SARS-CoV is a zoonotic virus that has crossed the species barriers to infect humans. Bats, which harbour a diverse pool of SARS-like CoVs (SL-CoVs, are believed to be the natural reservoir. The SARS-CoV surface Spike (S protein is a major antigenic determinant in eliciting neutralizing antibody production during SARS-CoV infection. In our previous work, we showed that a panel of murine monoclonal antibodies (mAbs that target the S2 subunit of the S protein are capable of neutralizing SARS-CoV infection in vitro (Lip KM et al, J Virol. 2006 Jan; 80(2: 941-50. In this study, we report our findings on the characterization of one of these mAbs, known as 1A9, which binds to the S protein at a novel epitope within the S2 subunit at amino acids 1111-1130. MAb 1A9 is a broadly neutralizing mAb that prevents viral entry mediated by the S proteins of human and civet SARS-CoVs as well as bat SL-CoVs. By generating mutant SARS-CoV that escapes the neutralization by mAb 1A9, the residue D1128 in S was found to be crucial for its interaction with mAb 1A9. S protein containing the substitution of D1128 with alanine (D1128A exhibited a significant decrease in binding capability to mAb 1A9 compared to wild-type S protein. By using a pseudotyped viral entry assay, it was shown that the D1128A substitution in the escape virus allows it to overcome the viral entry blockage by mAb 1A9. In addition, the D1128A mutation was found to exert no effects on the S protein cell surface expression and incorporation into virion particles, suggesting that the escape virus retains the same viral entry property as the wild-type virus.

  12. Insulin aspart pharmacokinetics

    DEFF Research Database (Denmark)

    Rasmussen, Christian Hove; Roge, Rikke Meldgaard; Ma, Zhulin;

    2014-01-01

    Background: Insulin aspart (IAsp) is used by many diabetics as a meal-time insulin to control postprandial glucose levels. As is the case with many other insulin types, the pharmacokinetics (PK), and consequently the pharmacodynamics (PD), is associated with clinical variability, both between...... to investigate and quantify the properties of the subcutaneous depot. Data from Brange et al. (1990) are used to determine the effects of insulin chemistry in subcutis on the absorption rate. Intravenous (i.v.) bolus and infusion PK data for human insulin are used to understand and quantify the systemic...... distribution and elimination (Porksen et al., 1997; Sjostrand et al., 2002). PK and PD profiles for type 1 diabetics from Chen et al. (2005) are analyzed to demonstrate the effects of IAsp antibodies in terms of bound and unbound insulin. PK profiles from Thorisdottir et al. (2009) and Ma et al. (2012b...

  13. Rubber recovery from centrifuged natural rubber latex residue using sulfuric acid

    Directory of Open Access Journals (Sweden)

    Wirach Taweepreda

    2013-04-01

    Full Text Available Waste latex sludge from centrifuged residue, which is a null by-product of concentrated latex manufacturing, wasdigested to retrieve the rubber by using sulfuric acid. It was found that the acid concentration and digestion time have aneffect on the amoun