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Sample records for glyceramido acetamido trideoxyhexose

  1. Synthesis and antidiabetic activity of β-acetamido ketones

    Directory of Open Access Journals (Sweden)

    Xing-hua Zhang

    2011-08-01

    Full Text Available This paper reports the use of trifluoroacetic acid as a catalyst in the Dakin–West reaction for the synthesis of β-acetamido ketones. The method has several advantages such as requiring only mild conditions and a low concentration of catalyst. Screening of 19 β-acetamido ketones for antidiabetic activity in vitro showed that their activity as peroxisome proliferator-activated receptor (PPAR agonists and as dipeptidyl peptidase 4 (DPP-IV inhibitors was fairly weak.

  2. 5-Acetamido-1H-pyrazole-4-carboxamide monohydrate

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    Lhoussaine El Ghayati

    2016-06-01

    Full Text Available There are two independent molecules of the title carboxamide compound, C6H8N4O2·H2O, as well as two independent water molecules in the asymmetric unit. The two independent carboxamide molecules differ primarily in the relative orientations of the peripheral methyl and amino groups. Intramolecular N—H...O hydrogen bonds assist in determining the orientations of the acetamido substituents. The three-dimensional crystal packing is directed by a large network of O—H...O, N—H...O, C—H...O and C—H...N hydrogen bonds.

  3. 2,4-dimethoxybenzyl: An amide protecting group for 2-acetamido glycosyl donors

    DEFF Research Database (Denmark)

    Kelly, N.M.; Jensen, Knud Jørgen

    2001-01-01

    2,4-Dimethoxybenzyl (Dmob) was used as an amide protecting group for 2-acetamido glycosyl donors. The N-Dmob group was introduced by imine formation between 2,4-dimethoxybenzaldehyde and d-glucosamine, followed by per-O-acylation, reduction to form the amine, and finally N-acetylation to give 1......,3,4,6-tetra-O-acetyl-2-deoxy-2-(2,4-dimetboxybenzylacetamido)-beta -D-glucopyranose. Selective 1-O-deacetylation and treatment with trichloroacetonitrile gave the corresponding trichloroacetimidate glycosyl donor. Lewis acid-promoted glycosylations of the model substrate 3-nitrobenzyl alcohol gave exclusively...... the P-glycoside product, either with or without the Dmob protecting group remaining depending on the reagent and conditions employed. The N-Dmob protected 1-O-acetate glucosyl donor gave higher glycosylation yields than the corresponding 2-acetamido glucosyl donor without Dmob protection....

  4. Synthesis and Antiviral Activity of 3-Aminoindole Nucleosides of 2-Acetamido-2-deoxy-D-glucose

    Energy Technology Data Exchange (ETDEWEB)

    Abdelrahman, Adel A. H.; Elessawy, Farag A.; Barakat, Yousif A. [Menoufia Univ., Shebin El-Koam (Egypt); Ellatif, Mona M. Abd [The British Univ. in Egypt, Cairo (Egypt)

    2012-10-15

    A new method for the construction of 3-aminoindole nucleosides of 2-acetamido-2-deoxy-D-glucose based is presented. Nitration and acetylation of the indole nucleosides by acetic anhydride-nitric acid mixture followed by reduction using silver catalyst (SNSM) impregnated on silica gel, afforded the corresponding amino indole nucleosides. The nucleosides were tested for antiviral activity against hepatitis B virus (HBV) to show different degrees of antiviral activities or inhibitory actions.

  5. Attempted synthesis of 2-acetamido and 2-amino derivatives of salacinol. Ring opening reactions.

    Science.gov (United States)

    Choubdar, Niloufar; Pinto, B Mario

    2006-06-09

    The attempted synthesis of the 2-acetamido and 2-amino derivatives of salacinol, a naturally occurring glycosidase inhibitor, is described. Reaction of the protected acetamidothioarabinitol unit with the cyclic sulfate derived from L-erythritol gave the corresponding sulfonium sulfate, which underwent ring opening to give an acyclic amido sulfate. The corresponding reaction of the protected azidothioarabinitol unit with the cyclic sulfate proceeded to give the sulfonium sulfate. However, upon reduction of the azido function to an amine it formed an acyclic ammonium sulfate.

  6. Conformational studies on pertrimethylsilyl derivatives of 2-acetamido-2-deoxyaldohexopyranoses by 220- and 300-MHz P.M.R. spectroscopy

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Streefkerk, D.G.; Bie, M.J.A. de

    1974-01-01

    The complete interpretation of high-resolution p.m.r. spectra and the accurate chemical shifts and coupling constants, obtained after computer simulation of the spectra, of the trimethylsilyl (TMS) derivatives of six 2-acetamido-2-deoxy-D-aldo-hexopyranoses are given. All pyranoid rings occur in the

  7. N-(2-Acetamido-2-deoxy-β-d-glucopyranosyl-N-(3-azidopropyl-O-methylhydroxylamine

    Directory of Open Access Journals (Sweden)

    Stefan Munneke

    2016-03-01

    Full Text Available The structure of the title compound, C12H23N5O6, solved using adequate data from a thin crystal plate, confirmed that this useful glycoconjugate was obtained in the ring-closed β-pyranose configuration with 4C1 conformation. The molecules are bound by O—H...O(OH hydrogen bonds, notably in a zigzag C(2 chain along the short b (screw axis, supplemented with an R22(12 O—H...O(carbonyl link along the a axis and other C(2 links. The absolute configuration was not unambiguously determined but was known from the synthetic chemistry, which used natural 2-acetamido-2-deoxy-d-glucose as the starting material.

  8. Facile synthesis of nitrophenyl 2-acetamido-2-deoxy-α-D-mannopyranosides from ManNAc-oxazoline

    Directory of Open Access Journals (Sweden)

    Karel Křenek

    2012-03-01

    Full Text Available The synthetic procedures for a large-scale preparation of o- and p-nitrophenyl 2-acetamido-2-deoxy-α-D-mannopyranoside are described. The synthetic pathway employs the glycosylation of phenol with ManNAc oxazoline, followed by nitration of the aromatic moiety yielding a separable mixture of the o- and p-nitrophenyl derivative in a 2:3 ratio.

  9. Combined experimental and computational studies on the physical and chemical properties of the renewable amide, 3-acetamido-5-acetylfuran.

    Science.gov (United States)

    Liu, Yi; Rowley, Christopher N; Kerton, Francesca M

    2014-12-15

    The pK(a) of 3-acetamido-5-acetylfuran (3A5AF) was predicted to be in the range 18.5-21.5 by using the B3LYP/6-311+G(2d,p) method and several amides as references. The experimental pK(a) value, 20.7, was determined through UV/Vis titrations. Its solubility was measured in methanol-modified supercritical CO2 (mole fraction, 3.23×10(-4), cloud points 40-80 °C) and it was shown to be less soluble than 5-hydroxymethylfurfural (5-HMF). Dimerization energies were calculated for 3A5AF and 5-HMF to compare hydrogen bonding, as such interactions will affect their solubility. Infrared and (1) H nuclear magnetic resonance spectra of 3A5AF samples support the existence of intermolecular hydrogen bonding. The highest occupied molecular orbital, lowest unoccupied molecular orbital, and electrostatic potential of 3A5AF were determined through molecular orbital calculations using B3LYP/6-311+G(2d,p). The π-π* transition energy (time-dependent density functional theory study) was compared with UV/Vis data. Calculated atomic charges were used in an attempt to predict the reactivity of 3A5AF. A reaction between 3A5AF and CH3MgBr was conducted. As 3A5AF is a recently developed renewable compound that has previously not been studied extensively, these studies will be helpful in designing future reactions and processes involving this molecule. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Studies of lanthanide(III) metal complexes of 7-(D-Α-amino-phenyl-acetamido)-3-methyl-3-cepham-4-carboxylic acid

    International Nuclear Information System (INIS)

    Pingalkar, S.R.; Deshpande, M.N.

    2002-01-01

    Eight new solid complexes of lanthanide(III) chlorides with 7-(DΑ aminophenyl-acetamido)-3-methyl-3-cepham-4-carboxylic acid have been synthesised. These complexes are characterised by elemental analysis, UV and IR spectra, magnetic moment and conductivity data. Inhibitory effect of these complexes and study of antibacterial activity is also undertaken. The IR spectral studies indicate that the ligand acts as tetradentate and it coordinates through nitrogen and oxygen. The general formula of the complexes is [LnL 2 (H 2 O) 2 ]Cl, where Ln = La(III), Ce(III), Pr(III) , Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III). L is 7-(D-Α-aminophenyl- acetamido)-3-methyl-3-cepham-4-carboxylic acid. Coordination number of central metal ion is 10. Inhibitory study of complexes on the corrosion of steel alloy in solution of nitric acid has been done. The inhibitor concentrations of 0.5 to 2% in 0.5 N HNO 3 were used and it was found that inhibitory efficiency increases in the order metal chloride < ligand < complex. Antibacterial activity of AAMCC ligand increases on complexation with lanthanides. (author)

  11. Synthesis of P1-(11-phenoxyundecyl)-P2-(2-acetamido-2-deoxy-3-O-α-D-rhamnopyranosyl-α-D-glucopyranosyl) diphosphate and P1-(11-phenoxyundecyl)-P2-(2-acetamido-2-deoxy-3-O-β-D-galactopyranosyl-α-D-galactopyranosyl) diphosphate for the investigation of biosynthesis of O-antigenic polysaccharides in Pseudomonas aeruginosa and Escherichia coli O104.

    Science.gov (United States)

    Torgov, Vladimir; Danilov, Leonid; Utkina, Natalia; Veselovsky, Vladimir; Brockhausen, Inka

    2017-12-01

    Two new phenoxyundecyl diphosphate sugars were synthesized for the first time: P 1 -(11-phenoxyundecyl)-P 2 - (2-acetamido-2-deoxy-3-O-α-D-rhamnopyranosyl-α-D-glucopyranosyl) diphosphate and P 1 -(11-phenoxyundecyl)-P 2 -(2-acetamido-2-deoxy-3-O-β-D-galactopyranosyl-α-D-galactopyranosyl) diphosphate to study the third step of biosynthesis of the repeating units of O-antigenic polysaccharides in Pseudomonas aeruginosa and E.coli O104 respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Synthesis, vibrational spectroscopic investigations, molecular docking, antibacterial studies and molecular dynamics study of 5-[(4-nitrophenyl)acetamido]-2-(4-tert-butylphenyl)benzoxazole

    Science.gov (United States)

    Sheena Mary, Y.; Al-Shehri, Mona M.; Jalaja, K.; Al-Omary, Fatmah A. M.; El-Emam, Ali A.; Yohannan Panicker, C.; Armaković, Stevan; Armaković, Sanja J.; Temiz-Arpaci, Ozlem; Van Alsenoy, C.

    2017-04-01

    Antimicrobial active 5-[(4-nitrophenyl)acetamido]-2-(4-tert-butylphenyl)benzoxazole (NATPB) was synthesized and observed IR, Raman bands are compared with the theoretically predicted wave numbers. In the IR spectrum the NH stretching wave number splits into a doublet with a noted difference and is red shifted from the computed value, which indicates the weakening of NH bond resulting in proton transfer to the neighbouring oxygen atom. The HOMO-LUMO plots reveal the charge transfer in the molecular system through the conjugated paths. The electrophilic and nucleophilic reactive sites are identified from the MEP plot. Mapping of average local ionization energy (ALIE) values to the electron density surface served us as a tool for prediction of molecule sites possibly prone to electrophilic attacks. Other important reactive centres of the title molecule were detected by calculations of Fukui functions. Calculations of bond dissociation energies (BDE) for hydrogen abstraction were used in order to assess whether the NATPB molecules is prone to autoxidation mechanism or not, while BDE of the remaining single acyclic bonds were used in order to determine the weakest bond. Interaction properties with water were investigated by molecular dynamics (MD) simulations and calculations of radial distribution functions (RDFs). The compound possessed broad spectrum activity against all of the tested Gram-positive and Gram-negative bacteria and yeasts, their minimum inhibitory concentrations (MICs) ranging between 32 and 128 μg/ml. The compound exhibited significant antibacterial activity (32 μg/ml) against an antibiotic resistant E. faecalis isolate, at same potency with the compared standard drugs vancomycin and gentamycin sulfate. The molecular docking studies show that the compound might exhibit inhibitory activity against CDK inhibitors.

  13. Reactive, spectroscopic and antimicrobial assessments of 5-[(4-methylphenyl) acetamido]-2-(4-tert-butylphenyl)benzoxazole: Combined experimental and computational study

    Science.gov (United States)

    Mary, Y. Sheena; Alzoman, Nourah Z.; Menon, Vidya V.; Al-Abdullah, Ebtehal S.; El-Emam, Ali A.; Panicker, C. Yohannan; Temiz-Arpaci, Ozlem; Armaković, Stevan; Armaković, Sanja J.; Van Alsenoy, C.

    2017-01-01

    The synthesis, FT-IR, FT-Raman and NMR spectral analysis of an antimicrobial active benzoxazole derivative, 5-[(4-methylphenyl)acetamido]-2-(4-tert-butylphenyl) benzoxazole (MPATB) is reported. The localization of HOMO, LUMO plots in the title compound over the title molecule shows the charge transfer in the molecular system through the conjugated paths.The electrophilic and nucleophilic sites are revealed from the molecular electrostatic potential map. The first hyperpolarizability of the title compound is greater than that of the standard nonlinear optical material urea and the title compound and its derivatives are good objects for further research in nonlinear optical analysis. Molecule sites prone to electrophilic attacks have been detected by calculation of average local ionization energies, while calculations of Fukui functions have provided additional information about the local reactivity properties. Bond dissociation energies have been calculated in order to investigate autoxidation possibilities of the title molecule, as well as to determine the weakest bonds and therefore the sites where process of degradation could start. Reactive properties with water have been investigated by molecular dynamics simulations and calculations of radial distribution functions. The compound possessed broad spectrum activity against all of the tested Gram-positive and Gram-negative bacteria and yeasts, their minimum inhibitory concentrations ranging between 8 and 128 μg/ml. The compound exhibited significant antifungal activity (64 μg/ml) against Candida krusei, at same potency with the compared standard drugs fluconazole. The docked title compound forms a stable complex with thymidylate synthase and got a binding affinity value of -8.5 kcal/mol and the title compound can be a lead compound for developing new anti-cancerous drug.

  14. 2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside confers neuroprotection in cell and animal models of ischemic stroke through calpain1/PKA/CREB-mediated induction of neuronal glucose transporter 3

    International Nuclear Information System (INIS)

    Yu, Shu; Cheng, Qiong; Li, Lu; Liu, Mei; Yang, Yumin; Ding, Fei

    2014-01-01

    Salidroside is proven to be a neuroprotective agent of natural origin, and its analog, 2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside (named SalA-4 g), has been synthesized in our lab. In this study, we showed that SalA-4 g promoted neuronal survival and inhibited neuronal apoptosis in primary hippocampal neurons exposed to oxygen and glucose deprivation (OGD) and in rats subjected to ischemia by transient middle cerebral artery occlusion (MCAO), respectively, and that SalA-4 g was more neuroprotective than salidroside. We further found that SalA-4 g elevated glucose uptake in OGD-injured primary hippocampal neurons and increased the expression and recruitment of glucose transporter 3 (GLUT3) in ischemic brain. Signaling analysis revealed that SalA-4 g triggered the phosphorylation of CREB, and increased the expression of PKA RII in primary hippocampal neurons exposed to OGD injury, while inhibition of PKA/CREB by H-89 alleviated the elevation in glucose uptake and GLUT3 expression, and blocked the protective effects of SalA-4 g. Moreover, SalA-4 g was noted to inhibit intracellular Ca 2+ influx and calpain1 activation in OGD-injured primary hippocampal neurons. Our results suggest that SalA-4 g neuroprotection might be mediated by increased glucose uptake and elevated GLUT3 expression through calpain1/PKA/CREB pathway. - Highlights: • A salidroside (Sal) analog (SalA-4 g) is prepared to be more neuroprotective than Sal. • SalA-4 g protected hippocampal neurons from oxygen and glucose deprivation insult. • SalA-4 g reduced ischemic injury after transient middle cerebral artery occlusion in rats. • Neuroprotection of SalA-4 g was mediated by GLUT3 level via calpain/PKA/CREB pathway

  15. The structure of the LPS O-chain of Fusobacterium nucleatum strain 25586 containing two novel monosaccharides, 2-acetamido-2,6-dideoxy-l-altrose and a 5-acetimidoylamino-3,5,9-trideoxy-gluco-non-2-ulosonic acid.

    Science.gov (United States)

    Vinogradov, Evgeny; St Michael, Frank; Cox, Andrew D

    2017-02-22

    Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. Recently, it has been gaining attention as a potential causative agent for colorectal cancer and is strongly linked with pregnancy complications including pre-term and still births. Little is known about the virulence factors of this organism, and thus we have initiated studies to examine the bacterium's surface glycochemistry. We isolated lipopolysaccharide (LPS) from F. nucleatum strain 25586 and purified and performed structural analysis on the O-antigen polysaccharide. The polysaccharide contained two novel sugars, 2-acetamido-2,6-dideoxy-l-altrose (l-6dAltNAc) and a 5-acetimidoylamino-3,5,9-trideoxy-gluco-non-2-ulosonic acid (Non5Am), which was tentatively assigned the l-glycero-l-gluco configuration. The polysaccharide was found to have a trisaccharide repeating unit, which is phosphorylated with phosphocholine (PCho), and the following structure was established: -[-4-β-Nonp5Am-4-α-l-6dAltpNAc3PCho-3-β-d-QuipNAc-]- We propose the trivial name 'fusaminic acid' for the novel nonulosonic acid. It is the first occurrence of a 9-deoxynonulosonic acid with a hydroxyl group at C-7, which is occupied by an amino group in all monosaccharides of this class described so far. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. 2-acetamido-2-deoxy-α-D-galactopyranoside antigen–lectin

    Indian Academy of Sciences (India)

    WINTEC

    After 3 h, Amberlite IR-120 (H+) resin was added to the reaction mixture, filtered and .... neutralized with Amberlite IR-120 resin (H+ form), filtered and the filtrate concentrated in vacuo. The resulting solid was ..... (a) Springer G F 1984 Science 224 1198; (b) Itzko- witz S H, Yuan M, Montgomery C K, Kjeldsen T,. Takahashi ...

  17. Indium-mediated allylation in carbohydrate synthesis: A short and efficient approach towards higher 2-acetamido-2-deoxy sugars

    Directory of Open Access Journals (Sweden)

    Christopher Albler

    2014-09-01

    Full Text Available Higher aminosugars are interesting targets in carbohydrate synthesis since these compounds play important roles in biological systems. However, their availability from natural sources is limited. Thus, in order to investigate their biological function, the development of facile and adaptable routes to this class of compounds is of fundamental importance. Our synthetic route towards these target molecules makes use of readily accessible pentoses and hexoses, which are subjected to indium-mediated two-carbon chain elongation. Subsequent ozonolysis and treatment with base yields α,β-unsaturated aldehydes, which are stereoselectively epoxidized using Jørgenson’s protocol. After Wittig chain elongation the obtained allylic epoxides were regio- and stereoselectively opened with trimethylsilyl azide under palladium catalysis. Finally, a suitable deprotection protocol, starting with acidic acetate cleavage and ozonolysis was established. Peracetylation of the products simplifies purification and subsequent azide reduction followed by final deacetylation using methanolic sodium methoxide furnishes the title compounds.

  18. Facile synthesis of nitrophenyl 2-acetamido-2-deoxy-alpha-D-mannopyranosides from ManNAc-oxazoline

    Czech Academy of Sciences Publication Activity Database

    Křenek, Karel; Šimon, Petr; Weignerová, Lenka; Fliedrová, Barbora; Kuzma, Marek; Křen, Vladimír

    2012-01-01

    Roč. 8, MAR 2012 (2012), s. 428-432 ISSN 1860-5397 R&D Projects: GA ČR GAP207/10/0321; GA MŠk(CZ) 7E11011 Keywords : alpha-ManNAc * glycosylation * glycosidase Subject RIV: CC - Organic Chemistry Impact factor: 2.801, year: 2012

  19. Synthesis and Preliminary Antimicrobial Activities of New Arylideneamino-1,3,4-thiadiazole-(thio/dithio-acetamido Cephalosporanic Acids

    Directory of Open Access Journals (Sweden)

    Shakir Mahmood Alwan

    2012-01-01

    Full Text Available New derivatives of 7-aminocephalosporanic acid 1–8 were synthesized by acylation of the 7-amino group of the cephem nucleus with various arylidinimino-1,3,4-thiadiazole-thio(or dithio-acetic acid intermediates 3a–d and 5a–d, respectively, so the acyl side chains of these new cephalosporins contained a sulfide or disulfide bond. This unique combination of a Schiff base with the sulfide or disulfide bonds in the acyl side chain afforded new cephalosporins of reasonable potencies, some of which were found to possess moderate activities against the tested microorganisms. Their chemical structures were characterized by ¹H-NMR, IR spectroscopy and elemental microanalysis. Preliminary in vitro antimicrobial activities of the prepared cephalosporins were investigated using a panel of selected microorganisms. Results indicated that the newly synthesized cephalosporins containing disulfide bonds (compounds 5–8 exhibited better activities against Staphylococcus aureus and Escherichia coli. The cephalosporins cross-linked by a sulfide bond (compounds 1–4 showed a slight change in antimicrobial activities when compared with that of the reference cephalosporin (cephalexin.

  20. Methyl 2-acetamido-2-(4-hydroxy-2-methyl-1,3-dioxo-1,2,3,4-tetrahydroisoquinolin-4-yl-4-methylpentanoate

    Directory of Open Access Journals (Sweden)

    Hoong-Kun Fun

    2011-07-01

    Full Text Available In the isoquinoline ring system of the title molecule, C19H24N2O6, the N-heterocyclic ring is in a half-boat conformation. The molecular structure is stabilized by an intramolecular O—H...O hydrogen bond, which generates an S(7 ring motif. In the crystal, molecules are linked via intermolecular bifurcated N—H...(O,O and weak C—H...O hydrogen bonds into a three-dimensional network.

  1. Production of strand breaks in DNA in the presence of the hydroxylamine of SR-2508 (1-[N-(2-hydroxyethyl)acetamido]-2-nitroimidazole) at neutral pH

    International Nuclear Information System (INIS)

    Laderoute, K.R.; Eryavec, E.; McClelland, R.A.; Rauth, A.M.

    1986-01-01

    The protonated hydroxylamine of SR 2508 has been prepared by radiochemical reduction and then lyophilized, isolated as the hydrochloride salt, and characterized by proton magnetic resonance spectroscopy. Single strand breaks are produced in the plasmid pBR322 when aliquots of a neutralized solution of the hydroxylamine (10-20 mM) are added to air-equilibrated solutions of the plasmid immediately after adjusting the pH. No breaks are observed, if times greater than five min elapse before adding the neutralized hydroxylamine to DNA, or if oxygen is excluded from the reaction mixture. These results suggest that single strand breaks occur because of the existence of a short-lived reactive species, which is produced after pH adjustment. Observations that oxygen is consumed during the pH jump, H 2 O 2 produced and catalase, desferal and radical scavengers inhibit the reaction are consistent with the hydroxyl radical as the active agent

  2. N-Acetylhexosamine triad in one molecule: Chemoenzymatic introduction of 2-acetamido-2-deoxy-B-D-galactopyranosyluronic acid residue into a complex oligosacharide

    Czech Academy of Sciences Publication Activity Database

    Bojarová, Pavla; Křenek, Karel; Kuzma, Marek; Petrásková, Lucie; Bezouška, Karel; Namdjou, D-J.; Elling, L.; Křen, Vladimír

    2008-01-01

    Roč. 50, 2-4 (2008), s. 69-73 ISSN 1381-1177 R&D Projects: GA MŠk OC 170; GA ČR GA203/05/0172; GA MŠk(CZ) LC06010; GA MŠk OC D25.002 Grant - others:AV ČR(CZ) DAAD PPP -D7-CZ26/04 05D/03/44448 Institutional research plan: CEZ:AV0Z50200510 Keywords : talaromyces flavus * B-N-acetylhexosaminidase * galactopyranosiduronic acid Subject RIV: EE - Microbiology, Virology Impact factor: 2.015, year: 2008

  3. New iodo-acetamido cyanines for labeling cysteine thiol residues. A strategy for evaluating plasma proteins and their oxido-redox status.

    Science.gov (United States)

    Bruschi, Maurizio; Grilli, Stefano; Candiano, Giovanni; Fabbroni, Serena; Della Ciana, Leopoldo; Petretto, Andrea; Santucci, Laura; Urbani, Andrea; Gusmano, Rosanna; Scolari, Francesco; Ghiggeri, Gian Marco

    2009-01-01

    Two new iodoacetamide-substituted cyanines, C3NIASO3 and C5NIASO3, were synthesized starting from hemicyanine and were utilized for labeling plasma proteins. Specificity, sensitivity and feasibility for SH residues was tested utilizing an equimolar mixture of standard proteins and with normal plasma. Oxidized plasma proteins following H(2)O(2 )exposure and plasma from patients with focal glomerulosclerosis were analyzed as models of altered protein oxido-redox status. Following optimization of the assay (dye/protein ratio, pH), C3NIASO3 and C5NIASO3 gave a sensitivity slightly better than N-hydroxysuccinimidyl dyes for plasma proteins and were successfully employed for differential display electrophoresis (DIGE). Twenty-nine proteins were detected in normal plasma after 2-DE while less proteins were detected in plasma of patients with glomerulosclerosis. Following massive 'in vitro' oxidation with H(2)O(2), C3NIASO3 and C5NIASO3 failed to detect any residual SH, implicating massive oxidation. In conclusion, this study describes the synthesis of two new iodoacetamide cyanines that can be utilized for the analysis of plasma proteins with 2-DE and DIGE. They are also indicated for the definition of the oxido-redox status of proteins and were successfully utilized to extend the analysis of oxidation damage in patients with glomerulosclerosis.

  4. The crystal structure of 1-D-myo-inosityl 2-acetamido-2-deoxy-alpha-D-glucopyranoside deacetylase (MshB) from Mycobacterium tuberculosis reveals a zinc hydrolase with a lactate dehydrogenase fold.

    Science.gov (United States)

    Maynes, Jason T; Garen, Craig; Cherney, Maia M; Newton, Gerald; Arad, Dorit; Av-Gay, Yossef; Fahey, Robert C; James, Michael N G

    2003-11-21

    Mycothiol (1-D-myo-inosityl 2-(N-acetyl-L-cysteinyl)amido-2-deoxy-alpha-D-glucopyranoside, MSH or AcCys-GlcN-inositol (Ins)) is the major reducing agent in actinomycetes, including Mycobacterium tuberculosis. The biosynthesis of MSH involves a deacetylase that removes the acetyl group from the precursor GlcNAc-Ins to yield GlcN-Ins. The deacetylase (MshB) corresponds to Rv1170 of M. tuberculosis with a molecular mass of 33,400 Da. MshB is a Zn2+ metalloprotein, and the deacetylase activity is completely dependent on the presence of a divalent metal cation. We have determined the x-ray crystallographic structure of MshB, which reveals a protein that folds in a manner resembling lactate dehydrogenase in the N-terminal domain and a C-terminal domain consisting of two beta-sheets and two alpha-helices. The zinc binding site is in the N-terminal domain occupying a position equivalent to that of the NAD+ co-factor of lactate dehydrogenase. The Zn2+ is 5 coordinate with 3 residues from MshB (His-13, Asp-16, His-147) and two water molecules. One water would be displaced upon binding of substrate (GlcNAc-Ins); the other is proposed as the nucleophilic water assisted by the general base carboxylate of Asp-15. In addition to the Zn2+ providing electrophilic assistance in the hydrolysis, His-144 imidazole could form a hydrogen bond to the oxyanion of the tetrahedral intermediate. The extensive sequence identity of MshB, the deacetylase, with mycothiol S-conjugate amidase, an amide hydrolase that mediates detoxification of mycothiol S-conjugate xenobiotics, has allowed us to construct a faithful model of the catalytic domain of mycothiol S-conjugate amidase based on the structure of MshB.

  5. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Keywords. Solid-supported catalysts; silica-functionalized sulfonic acid (SFSA); sulfuric acid-modified polyethylene glycol-6000 (PEG-OSO3H); enolizable ketone; -acetamido ketone; -acetamido ester. ... Moreover, in this work, some novel -acetamido carbonyl compounds (i.e., one complex structure) are synthesized.

  6. A novel approach to inherently chiral calix[4]arenes by direct introduction of a substituent at the meta position

    NARCIS (Netherlands)

    Verboom, Willem; Bodewes, P.; Bodewes, Paul J.; van Essen, Georget; Timmerman, P.; van Hummel, G.J.; Harkema, Sybolt; Reinhoudt, David

    1995-01-01

    A novel method for the preparation of inherently chiral calix[4]arenes is described by direct introduction of a substituent in para-acetamido substituted calix[4]arenes. Bromination and nitration of mono(acetamido)calix[4]arenes 5, 6 afforded calix[4]arenes 7¿10, in which the substituent was

  7. Synthesis of 1-([1-14C]cyclohexyloxycarbonyloxy)ethyl 7β-[2-(2-aminothiazol-4-yl)acetamido]-3-[[[1-(2-dimethylamino-ethyl) -1H-tetrazol-5-yl]thio]methyl]ceph-3-em-4-carboxylate dihydrochloride ([14C]SCE-2174)

    International Nuclear Information System (INIS)

    Watanabe, Masazumi; Tada, Norio; Imanishi, Masayuki; Yamaoka, Masayoshi

    1988-01-01

    [ 14 C]SCE-2174, a new orally active cephalosporin, was labeled with carbon-14 starting from [1- 14 C]cyclohexanol (1). 1-Chloroethyl [1- 14 C]cyclohexyl carbonate (3) obtained by acylation of 1 with 1-chloroethyl chloroformate (2) was converted to iodide (4) which was condensed with the potassium salt of Cefotiam (5). [ 14 C]SCE-2174, having a specific activity of 672 MBq/mmol, was obtained in 13% overall radiochemical yield and had a radiochemical purity of 92%. (author)

  8. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Firouzabadid. Articles written in Journal of Chemical Sciences. Volume 124 Issue 2 March 2012 pp 501-508. Solid-supported sulfonic acid-containing catalysts efficiently promoted one-pot multi-component synthesis of -acetamido carbonyl compounds.

  9. Transformation of the Ionic X-Ray Contrast Agent Diatrizoate and Related Triiodinated Benzoates by Trametes versicolor

    Science.gov (United States)

    Rode, Ulrike; Müller, Rudolf

    1998-01-01

    Iodinated X-ray contrast agents are considered to be nondegradable by microorganisms. The decomposition of the ionic X-ray contrast agents Diatrizoate (3,5-di(acetamido)-2,4,6-triiodobenzoic acid) and Iodipamide (3,3′-adipoyl-diimino-di(2,4,6-triiodobenzoic acid) and related triiodinated benzoates (Acetrizoate [3-acetylamino-2,4,6-triiodobenzoic acid] and Aminotrizoate [3-amino-2,4,6-triiodobenzoic acid]) by Trametes versicolor has been investigated. The fungus was able to transform all tested triiodinated benzoates cometabolically. During transformation of these compounds, iodide was released, but deiodination was not complete. T. versicolor liberated traces of 14CO2 from uniformly ring-14C-labeled Diatrizoate (3,5-di(acetamido)-2,4,6-triiodobenzoate). Various extracellular metabolites were detected during transformation of the different substances. In the transformation of Diatrizoate, the three main metabolites were identified as 3,5-di(acetamido)-2,6-diiodobenzoic acid, 3,5-di(acetamido)-2,4-diiodobenzoic acid, and 3,5-di(acetamido)-2-iodobenzoic acid, suggesting reductive deiodinations in steps as initial transformation steps. PMID:9687487

  10. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Solid-supported sulfonic acid-containing catalysts efficiently promoted one-pot multi-component synthesis of -acetamido carbonyl compounds · Mohammad Ali Zolfigol Ardeshir Khazaei Abdolkarim Zare Mohammad Mokhlesi Tahereh Hekmat-Zadeh Alireza Hasaninejad Fatemeh Derakhshan-Panah Ahmad Reza ...

  11. Author Details

    African Journals Online (AJOL)

    Mokhlesi, M. Vol 65 (2012) - Articles Ionic Liquid 3-Methyl-1-sulphonic Acid Imidazolium Chloride {[Msim]Cl}: A Highly Efficient, Mild and Green Catalyst for the Synthesis of β-Acetamido Ketones Abstract PDF. ISSN: 0379-4350. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

  12. Author Details

    African Journals Online (AJOL)

    Derakhshan-Panah, F. Vol 65 (2012) - Articles Ionic Liquid 3-Methyl-1-sulphonic Acid Imidazolium Chloride {[Msim]Cl}: A Highly Efficient, Mild and Green Catalyst for the Synthesis of β-Acetamido Ketones Abstract PDF. ISSN: 0379-4350. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians ...

  13. Author Details

    African Journals Online (AJOL)

    Porbahi, S. Vol 65 (2012) - Articles Ionic Liquid 3-Methyl-1-sulphonic Acid Imidazolium Chloride {[Msim]Cl}: A Highly Efficient, Mild and Green Catalyst for the Synthesis of β-Acetamido Ketones Abstract PDF. ISSN: 0379-4350. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

  14. Author Details

    African Journals Online (AJOL)

    Hekmat-Zadeh, T. Vol 65 (2012) - Articles Ionic Liquid 3-Methyl-1-sulphonic Acid Imidazolium Chloride {[Msim]Cl}: A Highly Efficient, Mild and Green Catalyst for the Synthesis of β-Acetamido Ketones Abstract PDF. ISSN: 0379-4350. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians ...

  15. Antipyretic, analgesic, anti-inflammatory and cytotoxic effects of four ...

    African Journals Online (AJOL)

    ... and 2-acetamido-5-sulfonamidobenzoic acid (AMSABA, 4) were synthesized and evaluated for their analgesic, antipyretic, anti-inflammatory and cytotoxic activities. HASBA, AASBA and AMASBA showed higher analgesic activity than aspirin (ASA) at 100 mg/kg dose, while AMSABA showed the least analgesic property.

  16. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Abstract. SBA-15-Pr-SO3H catalyzes the multi-component condensation of aromatic aldehydes, ketones and acetonitrile in the presence of acetyl chloride at 80°C to afford -acetamido ketones in excellent yields. The catalyst can be recovered and recycled for subsequent reactions without any appreciable loss of efficiency.

  17. SBA-15-Pr–SO3H: An efficient, environment friendly and recyclable ...

    Indian Academy of Sciences (India)

    s12039-014-0762-1. SBA-15-Pr–SO3H: An efficient, environment friendly and recyclable heterogeneous nanoreactor catalyst for the one-pot multicomponent synthesis of β-acetamido ketones. KIUMARS BAHRAMIa,b,∗, MOHAMMAD M KHODAEIa ...

  18. Trifluoromethanesulfonic acid promoted Dakin–West reaction: An ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 124; Issue 2. Trifluoromethanesulfonic acid promoted Dakin-West reaction: An efficient and convenient synthesis of -acetamido ketones. Ravindra M Kumbhare Madabhushi Sridhar. Volume 124 Issue 2 March 2012 pp 495-500 ...

  19. Determination of the absolute configuration of monosaccharides in complex carbohydrates by capillary G.L.C.

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Gerwig, G.J.; Kamerling, J.P.

    1979-01-01

    The absolute configuration of neutral monosaccharides, 2-acetamido-2-deoxy sugars, and uronic acids can be determined by capillary g.l.c. on SE-30 after glycosidation with (-)-2-butanol and protection of the remaining polar groups. The method is illustrated by application to mixtures of the

  20. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. Fatemeh Derakhshan-Panah. Articles written in Journal of Chemical Sciences. Volume 124 Issue 2 March 2012 pp 501-508. Solid-supported sulfonic acid-containing catalysts efficiently promoted one-pot multi-component synthesis of -acetamido carbonyl compounds.

  1. Supporting Information

    Indian Academy of Sciences (India)

    Arash Ghorbani

    (acetonitrile) was evaporated. For further purification and for the separation of diastereomers, the crude product was dissolved in dichloromethane and purified by P-TLC n-hexane/acetone. (8/2) .Then, the residue was concentrated and dried to obtain corresponding β -acetamido ketones. Compounds Characterization Data.

  2. Afican Health Sciences Vol 9 No 4.pmd

    African Journals Online (AJOL)

    Administrator

    anhydrous Alcl3 in chlorobenzene resulted in the formation of substituted phenyl 4-amino cinnoline. 3-carboxamide 5a-i. Crude p-acetamido benzene sulphonyl chloride was treated with dilute ammonia followed by hydrolysis. P-amino benzene sulphonyl chloride 6 obtained was refluxed with DMF and substituted 4- amino ...

  3. Solid-supported sulfonic acid-containing catalysts efficiently ...

    Indian Academy of Sciences (India)

    Silica-functionalized sulfonic acid (SFSA) and sulfuric acid-modified polyethylene glycol-6000 (PEG-OSO3H) efficiently catalysed one-pot multi-component condensation of enolizable ketones or alkyl acetoacetates with arylaldehydes, acetonitrile and acetyl chloride to afford the corresponding -acetamido ketone or ester ...

  4. Ahmad Reza Moosavi-Zare

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. Ahmad Reza Moosavi-Zare. Articles written in Journal of Chemical Sciences. Volume 124 Issue 2 March 2012 pp 501-508. Solid-supported sulfonic acid-containing catalysts efficiently promoted one-pot multi-component synthesis of -acetamido carbonyl compounds.

  5. Copper(II tetrafluoroborate as mild and versatile catalyst for the

    Directory of Open Access Journals (Sweden)

    Jihillu. S. Yadav

    2008-12-01

    Full Text Available A variety of -acetamido ketones and ketoesters are readily prepared in high yields under extremelymild conditions via a three component coupling of aromatic aldehydes, enolizable ketones or -ketoesters andnitriles in the presence of 10 mol% of copper(II tetrafluoroborate and a stoichiometric amount of acetylchloride. A solution of 10 mol% of Cu(BF42 in acetonitrile provides a convenient reaction medium to carry out athree component reaction under mild conditions

  6. 40 CFR 180.473 - Glufosinate ammonium; tolerances for residues.

    Science.gov (United States)

    2010-07-01

    ...)-monoammonium salt) and its metabolites, 2-acetamido-4-methylphosphinico-butanoic acid and 3-methylphosphinico... Grain aspirated fractions 25 Grape 0.05 Hog, fat 0.40 Hog, meat 0.15 Hog, meat byproducts 6.0 Horse, fat 0.40 Horse, meat 0.15 Horse, meat byproducts 6.0 Juneberry 0.10 Lingonberry 0.10 Milk 0.15 Nut, tree...

  7. Synthesis of Orthogonally Protected Muramic Acid Building Blocks for Solid Phase Peptide Synthesis

    Directory of Open Access Journals (Sweden)

    Kristina Vlahoviček-Kahlina

    2015-07-01

    Full Text Available Muramic acid is found in many peptide natural products containing oligo(polysaccharide moieties. Taking into consideration that the Fmoc methodology is routinely used for solid-phase peptide synthesis, preparation of orthogonally protected muramic acid building blocks for total solid-phase synthesis of these natural products is of particular practical importance. Herein a simple and efficient synthesis of benzyl 2-amino-4,6-O-benzylidene-3-O-[(R-1-carboxyethyl]-2-deoxy-N-9-fluorenylmethyloxycarbonyl-α-D-glucopyranoside (6 from N-acetylglucosamine (1 is described. Important improvements over previous synthetic approaches to glucopyranosides 2 (benzyl 2-acetamido-2-deoxy-α-D-glucopyranoside and 3 (benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-α-D-glucopyranoside, key building blocks in preparation of 6, include synthesis simplification and efficient isolation and purification. Optically pure (S-2-chloropropionic acid 7 was prepared and introduced to the positon 3-O of sugar moiety to give compound 4 (benzyl 2-acetamido-4,6-O-benzylidene-3-O-[(R-1-carboxyethyl]-2-deoxy-α-D-glucopyranoside with the (R-configuration of the lactyl side-chain in excellent overall yield and optical purity. Deacetylation of amino group gave compound 5 (benzyl 2-amino-4,6-O-benzylidene-3-O-[(R-1-carboxyethyl]-2-deoxy-α-D-glucopyranoside suitable for incorporation of the Fmoc protecting group to give protected muramic acid derivative 6, a useful building block in peptide synthesis.

  8. Chemical synthesis of the tetrasaccharide repeating unit of the O-polysaccharide isolated from Azospirillum brasilense SR80.

    Science.gov (United States)

    Sarkar, Vikramjit; Mukhopadhyay, Balaram

    2015-04-10

    A linear strategy has been developed for the synthesis of the tetrasaccharide repeating unit of the O-polysaccharide from Azospirillum brasilense SR80. Stepwise glycosylation of the rationally protected thioglycoside donors activated by NIS in the presence of La(OTf)3 furnished the target tetrasaccharide. The glycosylation reactions resulted in the formation of the desired linkage with absolute stereoselectivity and afforded the required derivatives in good to excellent yields. The phthalimido group has been used as the precursor of the desired acetamido group to meet the requirement of 1,2-trans glycosidic linkage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Design, Synthesis and Characterization of Novel Arylamides Containing 1,2,4-triazole Nuclei for Possible Antimicrobial Activity

    Directory of Open Access Journals (Sweden)

    S. R. Dhol

    2004-01-01

    Full Text Available Diphenyl aceto hydrazide on reaction with carbon disulfide and potassium hydroxide gave potassium α,α-diphenyl acetamido dithiocarbamate, which on cyclisation with hydrazine hydrate yielded key intermediate 3-mercapto-4,N-amino-5-benzhydryl-1,2,4-triazoles. The key intermediate on condensation with different acid chloride afforded our titled compounds. The synthesised compounds have been confirmed elemental analyses and further supported by spectral data. All the synthesised compounds have been evaluated for their in vitroin vitro antimicrobial activity.

  10. N-[3-(tert-Butyldimethylsiloxymethyl-5-nitrophenyl]acetamide

    Directory of Open Access Journals (Sweden)

    David Barker

    2008-10-01

    Full Text Available The title compound, C15H24N2O4Si, was prepared by the reaction of (3-acetamido-5-nitrobenzylmethanol with tert-butyldimethylsilyl chloride and is a key intermediate in the synthesis of novel nonsymmetrical DNA minor groove-binding agents. There are two independent molecules in the structure, which differ primarily in the rotation about the C—O bond next to the Si atom. Two strong N—H...O hydrogen bonds align the molecules into a wide ribbon extending approximately parallel to the b axis.

  11. Synthesis of aryl b-N-acetylglucosamine desmodified at C-6 as potential antimicrobial agents; Sintese de b-N-acetilglicosaminideos de arila modificados em C-6 como potenciais agentes antimicrobianos

    Energy Technology Data Exchange (ETDEWEB)

    Manfrini, Rozangela Magalhaes; Souza Filho, Jose Dias de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Inst. de Ciencias Exatas; Figueireido, Rute Cunha; D' Angelis, Allison Fabiano; Prado, Maria Auxiliadora Fontes; Nunan, Elziria de Aguiar; Martins, Gabriela Aires; Alves, Ricardo Jose [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Faculdade de Farmacia. Dept. de Produtos Farmaceuticos]. E-mail: ricardodylan@farmacia.ufmg.br

    2008-07-01

    We report herein the synthesis of aryl beta-N-acetylglucosaminides containing azido, amino and acetamido groups at C-6 as potential antimicrobial agents. It was expected that these compounds could interfere with the biosynthesis and/or biotransformation of Nacetylglucosamine in fungi and bacteria. None of the compounds showed antimicrobial activity against bacteria (Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa), filamentous fungus (Aspergillus niger) and yeasts (Saccharomyces cerevisae, Candida albicans and Candida tropicallis), at the concentration of 1 mg/mL in agar diffusion assay. (author)

  12. ESTUDO DA GLICOSILAÇÃO DO CICLO-HEXANOL COM DIFERENTES DERIVADOS DE D-GLICOSAMINA E PROMOTORES DE GLICOSILAÇÃO PELO MÉTODO DE KOENIGS-KNORR

    Directory of Open Access Journals (Sweden)

    Lucas L. Franco

    2016-01-01

    Full Text Available We report herein a study on the glycosylation of cyclohexanol with four D-glucosamine-based peracetylated glycosyl chlorides bearing different substituents at C-2 and three glycosylation promoters, silver carbonate, silver triflate and mercury II chloride/mercury II oxide, by the Koenigs-Knorr method. Under the conditions studied, glycosylation was successful only when 3,4,6-tri-O -acetyl-2-deoxy-2-phthalimido-α-D-glucopyranosyl chloride was used as the glycosyl donor, with silver carbonate proving the best promoter. In order to investigate the influence of the nature of the halogen at C-1, we also carried out the glycosylation of cyclohexanol with 3,4,6-tri-O -acetyl-2-deoxy-2-phthalimido-α-D-glucopyranosyl bromide, a more reactive glycosyl donor. As expected, the yield with the bromide derivative was higher with the three promoters and, again, silver carbonate was the most efficient promoter. Finally, to illustrate the well-known efficient procedure for conversion of the phtalimido group at C-2 to the corresponding acetamido group, cyclohexyl 3,4,6-tri-O -acetyl-2-deoxy-2-phtalimido-β-D-glucopyranoside was converted into cyclohexyl 2-deoxy-2-acetamido-β-D-glucopyranoside in two steps, namely, hydrazinolysis of the phtalimido group followed by chemoselective acetylation of the free amino group by treatment with acetic anhydride in methanol, at 77% overall yield.

  13. Recognition of chitin and proteins in invertebrate cuticles using analytical pyrolysis/gas chromatography and pyrolysis/gas chromatography/mass spectrometry.

    Science.gov (United States)

    Stankiewicz, B A; Van Bergen, P F; Duncan, I J; Carter, J F; Briggs, D E; Evershed, R P

    1996-01-01

    Flash pyrolysis/gas chromatography (py/GC) and py/GC/mass spectrometry (MS) have been utilized to characterize the cuticles of invertebrates chemically. Pyrolysis products have been identified and assigned to specific cuticular components. Acetylpyridones, acetamidofuran, 3-acetamido-5-methylfuran and 3-acetamido-(2 and 4)-pyrones are proposed as characteristic pyrolysis markers for chitin. Pyrolysis products displaying ions of m/z 70, 154, 168, 194 are thought to derive from diketopiperazine structures and provide potential markers for proteins and peptides in which proline, alanine, valine, arginine and glycine are the dominant amino acids. These products, constituting specific pyrolysis markers for invertebrate cuticles, may reflect the amino acid composition of their constituent structural proteins. The source of the various pyrolysis products of proteins has been verified by pyrolysis of reference proteins, peptides and amino acid mixtures. The presence of additional pyrolysis products related directly to histidine and catechol moieties is consistent with the chemical structure and composition proposed for arthropod cuticles based on recent work utilizing solid state 13C and 15N nuclear magnetic resonance. This study constitutes the first comprehensive chemical characterization of the pyrolysis products of invertebrate cuticles and provides the basis for future investigations requiring qualitative screening for cross-linked chitin and proteins in modern and fossil cuticles and in materials, e.g. geopolymers, that may be derived from them.

  14. Novel broad-spectrum and long-acting parenteral cephalosporins having an acyl cyanamide moiety at the C-3 terminal: Synthesis and structure-activity relationships.

    Science.gov (United States)

    Yokoo, Katsuki; Yamawaki, Kenji; Yoshida, Yutaka; Yonezawa, Shuji; Yamano, Yoshinori; Tsuji, Masakatsu; Hori, Toshihiko; Nakamura, Rio; Ishikura, Koji

    2016-11-29

    A series of novel 7β-[2-(2-aminothiazole-4-yl)-2-(Z)-(alkoxyimino)acetamido]-cephalosporins having pyridinium-linked acyl cyanamide at the C-3 position were prepared and their antibacterial activities and pharmacokinetics profiles were evaluated. Most of the compounds exhibited potent antibacterial activities against penicillin-resistant Streptococcus pneumoniae (PRSP) and β-lactamase non-producing penicillin-resistant Haemophilus influenzae (BLNAR). Introduction of a propenyl group between the cephalospoin core and the side chains at the C-3 position improved the pharmacokinetics profile. Among these compounds, 7β-[2-(2-aminothiazole-4-yl)-2-(Z)- (alkoxyimino)acetamido]-3-(pyridin-1-ium-1-yl)prop-1-en-1-yl)cephalosporins (32j) showed well-balanced antibacterial activity against S. pneumoniae and H. influenzae which included resistant strains and also other Gram-positive or Gram-negative pathogens. Furthermore, 32j showed a long half-life comparable to that of Ceftriaxone in mice and monkeys. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  15. Reduction process of nitroxyl spin probes used in Overhauser-enhanced magnetic resonance imaging: An ESR study

    Energy Technology Data Exchange (ETDEWEB)

    Meenakumari, V.; Premkumar, S.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, NMSSVN College, Nagamalai, Madurai-625 019, Tamilnadu (India); Jawahar, A. [Department of Chemistry, NMSSVN College, Nagamalai, Madurai-625 019, Tamilnadu (India)

    2016-05-23

    The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM {sup 14}N- labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters, such as line width, hyperfine coupling constant, g-factor, signal intensity ratio and rotational correlation time were estimated. The 3-carbamoyl-PROXYL radical has narrowest line width and fast tumbling motion compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO, and 4-acetamido-TEMPO radicals. The half life time and decay rate were estimated for 1mM concentration of {sup 14}N- labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. From the results, the 3-carbamoyl-PROXYL has long half life time and high stability compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO and 4-acetamido-TEMPO radicals. Therefore, this study reveals that the 3-carbamoyl-PROXYL radical can act as a good redox sensitive spin probe for Overhauser-enhanced Magnetic Resonance Imaging.

  16. 2-Acetyl-amino-1,3,4,6-tetra-O-(tri-methyl-silyl)-2-de-oxy-α-d-gluco-pyran-ose.

    Science.gov (United States)

    Cheng, Zhao-Dong; Cui, Yan-Li; Mao, Jian-Wei

    2013-06-01

    The title compound, C20H47NO6Si4, was synthesized by per-O-tri-methyl-silylation of N-acetyl-d-glucosa-mine using chloro-tri-methyl-silane in the presence of hexa-methyl-disiloxane. The tri-methyl-silyl group and acetamido group are located on the same side of the pyran ring, showing an α-configuration glycoside. One of the tri-methyl-silyl groups is disordered over two orientations, with site-occupancy factors of 0.625 (9) and 0.375 (9). In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into supra-molecular chains along the a-axis direction.

  17. 2-Acetyl­amino-1,3,4,6-tetra-O-(tri­methyl­silyl)-2-de­oxy-α-d-gluco­pyran­ose

    Science.gov (United States)

    Cheng, Zhao-Dong; Cui, Yan-Li; Mao, Jian-Wei

    2013-01-01

    The title compound, C20H47NO6Si4, was synthesized by per-O-tri­methyl­silylation of N-acetyl-d-glucosa­mine using chloro­tri­methyl­silane in the presence of hexa­methyl­disiloxane. The tri­methyl­silyl group and acetamido group are located on the same side of the pyran ring, showing an α-configuration glycoside. One of the tri­methyl­silyl groups is disordered over two orientations, with site-occupancy factors of 0.625 (9) and 0.375 (9). In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into supra­molecular chains along the a-axis direction. PMID:23795087

  18. Synthesis of a Spirocyclic Oxetane-Fused Benzimidazole

    Directory of Open Access Journals (Sweden)

    Michael Gurry

    2015-07-01

    Full Text Available A new synthesis of 2-oxa-7-azaspiro[3.5]nonane is described. Spirocyclic oxetanes, including 2-oxa-6-azaspiro[3.3]heptane were converted into o-cycloalkylaminoacetanilides for oxidative cyclizations using Oxone® in formic acid. The expanded spirocyclic oxetane successfully gave the [1,2-a] ring-fused benzimidazole. X-ray crystal structure of the resultant new tetracyclic system, 1ʹ,2ʹ-dihydro-4ʹH-spiro[oxetane-3,3ʹ-pyrido[1,2-a]benzimidazole] and the azetidine ring-opened adduct, N-(2-acetamido-4-bromophenyl-N-{[3-(chloromethyl oxetan-3-yl]methyl}acetamide are disclosed.

  19. Galactose 6-sulfate sulfatase activity in Morquio syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Yutaka, T.; Okada, S.; Kato, T.; Inui, K.; Yabuuhi, H. (Osaka Univ. (Japan). Faculty of Medicine)

    1982-07-01

    The authors have prepared a new substrate, o-..beta..-D-sulfo-galactosyl-(1-4)-..beta..-D-6-sulfo-2-acetamido-2-deoxyglucosyl-(1-4)-D-(1-/sup 3/H)galactitol, from shark cartilage keratan sulfate, for the assay of galactose 6-sulfate sulfatase activity. Using this substrate, they found there was a striking deficiency of galactose 6-sulfate sulfatase activity, in addition to the known deficiency of N-acetylgalactosamine 6-sulfate sulfatase, in the cultured skin fibroblasts of patients with Morquio syndrome. Their results could be explained by the hypothesis that accumulation of keratan sulfate and chondroitin 6-sulfate in Morquio syndrome is due to a deficiency of galactose 6-sulfate sulfatase and N-acetylgalactosamine 6-sulfate sulfatase activity, which are necessary for the degradation of these two mucopolysaccharides.

  20. Galactose 6-sulfate sulfatase activity in Morquio syndrome

    International Nuclear Information System (INIS)

    Yutaka, T.; Okada, S.; Kato, T.; Inui, K.; Yabuuhi, H.

    1982-01-01

    The authors have prepared a new substrate, o-β-D-sulfo-galactosyl-(1-4)-β-D-6-sulfo-2-acetamido-2-deoxyglucosyl-(1-4)-D-[1- 3 H]galactitol, from shark cartilage keratan sulfate, for the assay of galactose 6-sulfate sulfatase activity. Using this substrate, they found there was a striking deficiency of galactose 6-sulfate sulfatase activity, in addition to the known deficiency of N-acetylgalactosamine 6-sulfate sulfatase, in the cultured skin fibroblasts of patients with Morquio syndrome. Their results could be explained by the hypothesis that accumulation of keratan sulfate and chondroitin 6-sulfate in Morquio syndrome is due to a deficiency of galactose 6-sulfate sulfatase and N-acetylgalactosamine 6-sulfate sulfatase activity, which are necessary for the degradation of these two mucopolysaccharides. (Auth.)

  1. Prolongation of latencies for passive avoidance responses in rats treated with aniracetam or piracetam.

    Science.gov (United States)

    Yamada, K; Inoue, T; Tanaka, M; Furukawa, T

    1985-04-01

    Effects of aniracetam (1-anysoyl-2-pyrrolodone) and piracetam (1-acetamido-2-pyrrolidone) on passive avoidance behavior were studied in 2 and 18 months old rats using a step-down passive avoidance task. Repeated administration of aniracetam (30 and 50 mg/kg, IP X 5 days) or piracetam (100 mg/kg, IP X 5 days) significantly prolonged step-down latencies for a passive avoidance task in 2 months old rats. Administration of aniracetam (50 mg/kg, IP) or piracetam (100 mg/kg, IP), however, did not affect locomotor activity. This prolongation of latencies was also seen with oral administration of aniracetam (50 mg/kg X 5 days). Similar prolongation of latencies also occurred in 18 months old rat treated with aniracetam (50 mg/kg, IP X 5 days). The results imply that aniracetam may improve learning and/or memory in 2 and 18 months old rats.

  2. Isolation and Characterization of Chitosan-Producing Bacteria from Beaches of Chennai, India

    Directory of Open Access Journals (Sweden)

    Kuldeep Kaur

    2012-01-01

    Full Text Available Chitosan is a deacetylated product of chitin produced by chitin deacetylase, an enzyme that hydrolyses acetamido groups of N-acetylglucosamine in chitin. Chitosan is a natural polymer that has great potential in biotechnology and in the biomedical and pharmaceutical industries. Commercially, it is produced from chitin via a harsh thermochemical process that shares most of the disadvantages of a multistep chemical procedure. It is environmentally unsafe and not easily controlled, leading to a broad and heterogeneous range of products. An alternative or complementary procedure exploiting the enzymatic deacetylation of chitin could potentially be employed, especially when a controlled and well-defined process is required. In this study, 20 strains of bacteria were isolated from soil samples collected from different beaches of Chennai, India. Of these 20 bacterial strains, only 2 strains (S3, S14 are potent degrader of chitin and they are also a good producer of the enzyme chitin deacetylase so as to release chitosan.

  3. Skrining dan Evaluasi Aktivitas Kitinase dari Sembilan Isolat Bakteri Lokal

    Directory of Open Access Journals (Sweden)

    Baitha Palanggatan Maggadani

    2017-04-01

    Full Text Available Chitinase is an enzyme that degrades chitin on β-1,4-acetamido-2-deoxy-D-glycoside bound to produce Chitin oligosaccharide or its soluble monomer, N-acetylglucosamine (NAG. Chitinase are usually produced naturally by chitinolytic microorganism that are found in soil or water environment. Chitinase have been widely used for biocontrol agents of plant pests. The product from chitinase hydrolysis can be used as antiinflammatory agent and anti hyperpigmentation. This research was aimed to screen and evaluate the chitinolytic ability of 9 isolate. The best isolate was the one which produced high chitinolytic activity and hydrolyzed chitin into NAG. 9 isolate were examined and BPPTCC-2 was the best isolate which produced highest level of chitinolytic activity 0.1780 U/ml. The chitinase was able to hydrolyzed chitin resulting high yields of NAG 11.5% as the only product.

  4. A novel N-linked flagellar glycan from Methanococcus maripaludis.

    Science.gov (United States)

    Kelly, John; Logan, Susan M; Jarrell, Ken F; VanDyke, David J; Vinogradov, Evgeny

    2009-03-31

    The archaea Methanococcus maripaludis strain Mm900 produces flagella that are glycosylated with an N-linked tetrasaccharide. Mass spectrometric analysis of flagellar tryptic peptides identified a number of tryptic glycopeptides carrying a glycan of mass 1036.4Da, and fragmentation of the glycan oxonium ion indicated that the glycan was a tetrasaccharide. The glycan was purified, following extensive pronase digestion of flagellar filaments, by size-exclusion and anion-exchange chromatography. NMR spectroscopy revealed that the glycan had the following structure: Sug-4-beta-ManNAc3NAmA6Thr-4-beta-GlcNAc3NAcA-3-beta-GalNAc-Asn where Sug is a novel monosaccharide unit, (5S)-2-acetamido-2,4-dideoxy-5-O-methyl-alpha-l-erythro-hexos-5-ulo-1,5-pyranose. This oligosaccharide has significant similarity to the oligosaccharide that was found previously in Methanococcus voltae.

  5. PDT-induced apoptosis in bladder carcinoma cells

    Science.gov (United States)

    Bachor, Ruediger; Reich, Ella D.; Kleinschmidt, Klaus; Repassy, Denes; Hautmann, Richard E.

    1999-02-01

    Photodynamic therapy (PDT) is a highly efficient inducer of apoptosis in EY-28 bladder carcinoma cells, resulting in extensive DNA fragmentation. Bladder carcinoma cells EY-28 (Tumorbank Heidelberg, Germany) were incubated for 1 h with 1 (mu) g AamTPPn/ml or 2 (mu) g AamTPPn/ml. After incubation cells were refed with complete medium and irradiated with 0.75 J/cm2. To identify apoptotic cells, a in situ cell death detection kit POD (Boehringer Mannheim, Germany) was used. The chromatin condensation characteristic to apoptotic cells was detected by transmission electron microscopy. Using 1 (mu) g AamTPPn/ml and 2 (mu) g AamTPPn/ml (9-Acetamido-2,7,12,17- tetra-n-Porpylporphycene), respectively, and irradiation at 0.75 J/cm2, a percentage of 36.9% and 54.7%, respectively, of apoptotic cells was detected.

  6. Skin secretion of Siphonops paulensis (Gymnophiona, Amphibia forms voltage-dependent ionic channels in lipid membranes

    Directory of Open Access Journals (Sweden)

    E.F. Schwartz

    2003-09-01

    Full Text Available The effect of the skin secretion of the amphibian Siphonops paulensis was investigated by monitoring the changes in conductance of an artificial planar lipid bilayer. Skin secretion was obtained by exposure of the animals to ether-saturated air, and then rinsing the animals with distilled water. Artificial lipid bilayers were obtained by spreading a solution of azolectin over an aperture of a Delrin cup inserted into a cut-away polyvinyl chloride block. In 9 of 12 experiments, the addition of the skin secretion to lipid bilayers displayed voltage-dependent channels with average unitary conductance of 258 ± 41.67 pS, rather than nonspecific changes in bilayer conductance. These channels were not sensitive to 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid or tetraethylammonium ion, but the experimental protocol used does not permit us to specify their characteristics.

  7. Mass spectrometric investigation of synthetic glycoside of muramyl dipeptide immobilized on fumed silica surface

    International Nuclear Information System (INIS)

    Kulik, Tetiana V.; Azizova, Liana R.; Palyanytsya, Borys B.; Zemlyakov, Alexander E.; Tsikalova, Victoria N.

    2010-01-01

    N-Acetylmuramyl-L-alanyl-D-isoglutamine or muramyl dipeptide is a cleavage product of peptidoglycan by lysozyme. This study explored the use of the temperature-programmed desorption mass spectrometry (TPDMS) in analysis of glycoside of muramyl dipeptide: O-{(4-tert-butylcyclohexyl)-2-acetamido-2, 3-dideoxy-β-D-glucopyranoside-3-yl}-D-lactoyl-L-alanyl-D-isoglutamine (MDP) on the surface of fumed silica. Stages of pyrolysis of MDP in condensed state and on the silica surface have been determined. Three stages have been clear identified under pyrolysis of MDP on the silica surface. Kinetic parameters of thermal reactions on the fumed silica surface and in the condensed state have been calculated.

  8. Crystal structure of an apremilast ethanol hemisolvate hemihydrate solvatomorph

    Directory of Open Access Journals (Sweden)

    Yun-Deng Wu

    2017-06-01

    Full Text Available The title compound, C22H24N2O7S·0.5C2H5OH·0.5H2O {systematic name: (S-4-acetamido-2-[1-(3-ethoxy-4-methoxyphenyl-2-(methylsulfonylethyl]isoindoline-1,3-dione ethanol hemisolvate hemihydrate}, is a novel solvatomorph of apremilast (AP, which is an inhibitor of phosphodiesterase 4 (PDE4 and is indicated for the treatment of adult patients with active psoriatic arthritis. The asymmetric unit contains one molecule of AP and disordered molecules of ethanol and water, both with half occupancy. The dihedral angle between the planes of the phenyl ring and the isoindole ring is 67.9 (2°. Extensive intra- and intermolecular hydrogen bonds help to stabilize the molecular conformation and sustain the crystal packing.

  9. Synthesis of aminoaldonic acids

    DEFF Research Database (Denmark)

    Jørgensen, Christel Thea

    With the aim of synthesising aminoaldonic acids, two 2-acetamido-2-deoxyaldonolactones with D-galacto (6) and D-arabino (11) configuration were prepared from acetylated sugar formazans in analogy with a known procedure. Empolying the same procedure to acetylated sugar phenylhydrazones gave mixtures......,4-lactone, respectively. A 2,3-aziridino-2,3-dideoxypentonamide 70 was also prepared from D-glucono-1,5-lactone. The lactones were converted into methyl 3,4-O-isopropylidene-2-O-sulfonyl esters 42, 50, 62 and 68, which upon treatment with concentrated aqueous ammonia yielded the aziridino compounds...... and 82, respectively. The aminolactone 84 was converted into the corresponding amino sugar 89.With the aim of synthesising substrates for the Pictet-Spengler reaction three 4-aldehydo acetamidodideoxytetronolactones 92, 97 and 103 were prepared by periodate cleavage of the corresponding hexonolactones...

  10. Structures of the K35 and K15 capsular polysaccharides of Acinetobacter baumannii LUH5535 and LUH5554 containing amino and diamino uronic acids.

    Science.gov (United States)

    Shashkov, Alexander S; Liu, Bin; Kenyon, Johanna J; Popova, Anastasiya V; Shneider, Mikhail M; Senchenkova, Sof'ya N; Arbatsky, Nikolay P; Miroshnikov, Konstantin A; Wang, Lei; Knirel, Yuriy A

    2017-08-07

    Capsular polysaccharides were isolated from A. baumannii LUH5535 (K35 CPS) and LUH5554 (K15 CPS) and studied by 1D and 2D 1 H and 13 C NMR spectroscopy. The CPSs were found to consist of linear tetrasaccharide repeats (K units) containing 2-acetamido-2-deoxy-d-galacturonic acid (K35) or 2,3-diacetamido-2,3-deoxy-d-glucuronic acid (K15) and 2,4-diacetamido-2,4,6-trideoxy-d-glucose (both CPSs). The K35 unit includes three O-acetyl groups on different GalNAcA residues. A. baumannii LUH5535 and LUH5554 carry the KL35 and KL15 gene clusters, respectively, and putatively assigned functions of genes in these clusters were consistent with the CPS structures established. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Molecular Analysis of the Gene Encoding a Novel Transglycosylative Enzyme from Alteromonas sp. Strain O-7 and Its Physiological Role in the Chitinolytic System

    Science.gov (United States)

    Tsujibo, Hiroshi; Kondo, Norihiko; Tanaka, Keiko; Miyamoto, Katsushiro; Baba, Nao; Inamori, Yoshihiko

    1999-01-01

    We purified from the culture supernatant of Alteromonas sp. strain O-7 and characterized a transglycosylating enzyme which synthesized β-(1→6)-(GlcNAc)2, 2-acetamido-6-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-2-deoxyglucopyranose from β-(1→4)-(GlcNAc)2. The gene encoding a novel transglycosylating enzyme was cloned into Escherichia coli, and its nucleotide sequence was determined. The molecular mass of the deduced amino acid sequence of the mature protein was determined to be 99,560 Da which corresponds very closely with the molecular mass of the cloned enzyme determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular mass of the cloned enzyme was much larger than that of enzyme (70 kDa) purified from the supernatant of this strain. These results suggest that the native enzyme was the result of partial proteolysis occurring in the N-terminal region. The enzyme showed significant sequence homology with several bacterial β-N-acetylhexosaminidases which belong to family 20 glycosyl hydrolases. However, this novel enzyme differs from all reported β-N-acetylhexosaminidases in its substrate specificity. To clarify the role of the enzyme in the chitinolytic system of the strain, the effect of β-(1→6)-(GlcNAc)2 on the induction of chitinase was investigated. β-(1→6)-(GlcNAc)2 induced a level of production of chitinase similar to that induced by the medium containing chitin. On the other hand, GlcNAc, (GlcNAc)2, and (GlcNAc)3 conversely repressed the production of chitinase to below the basal level of chitinase activity produced constitutively in medium without a carbon source. PMID:10464221

  12. Spectrally Undiscerned Isomers Might Lead to Erroneous Determination of Water Exchange Rates of paraCEST Eu(III) Agents.

    Science.gov (United States)

    Cakić, Nevenka; Tickner, Ben; Zaiss, Moritz; Esteban-Gómez, David; Platas-Iglesias, Carlos; Angelovski, Goran

    2017-07-17

    We report a detailed study of the solution structure and water exchange rate of a Eu(III) complex with the cyclen-based ligand L 1 , containing (S)-2-(2-acetamido)-3-(4-(trifluoromethyl)phenyl)propanoate pendant arms at positions 1 and 7 of the cyclen ring and acetylglycinate pendants at positions 4 and 10. The EuL 1 complex was characterized by a combination of NMR and luminescence spectroscopy and density functional theory (DFT) calculations. The chemical exchange saturation transfer (CEST) spectra obtained at different temperatures and saturation powers present a CEST signal attributed to the coordinated water molecule. However, the spectra recorded at low temperatures (10 °C) and low saturation powers revealed the presence of two different species with coordinated water molecules having very similar chemical shifts. Determination of the water exchange rates of the coordinated water molecules was carried out by using the Bloch four-pool model that accounts for the presence of these isomers, and this model was compared to conventional methods for CEST quantification, namely the Omega plot and QUESP (quantification of exchange rate as a function of saturation power), which assume the presence of a single CEST active species. The results indicated that only the four-pool Bloch equations provide reasonable water exchange rates and activation parameters. Solution NMR studies and DFT calculations indicated that the two isomers present in solution correspond to the SS-Δ(λλλλ) and SS-Λ(δδδδ) isomers, which present capped square-antiprismatic (SAP) coordination environments. Additional NMR studies on the EuL 2 and EuL 3 complexes, which present four (S)-2-(2-acetamido)-3-(4-(trifluoromethyl)phenyl)propanoate or acetylglycinate pendant arms, respectively, confirm the results obtained for EuL 1 .

  13. Synthesis of specifically deuterated S-benzylcysteines and of oxytocin and related diastereomers deuterated in the half-cystine positions

    Energy Technology Data Exchange (ETDEWEB)

    Upson, D.A.; Hruby, V.J.

    1976-04-16

    S-Benzylcysteine derivatives specifically deuterated at the ..cap alpha.. carbon only, the ..beta.. carbon only, and at both the ..cap alpha.. and ..beta.. carbons have been synthesized. These labeled compounds have been enzymatically resolved and the enantiomers and reacemates have been converted to the N-tert-butyloxycarbonyl derivatives. The deuterium labels were not exchanged under the conditions of the syntheses. Condensation of the sodium salt of diethyl ..cap alpha..-acetami-domalonate with benzyl chloromethyl sulfide followed by hydrolysis with DCl afforded S-benzyl-DL-(..cap alpha..-/sup 2/H/sub 1/) cysteine. Acetylation followed by treatment with hog renal acylase separated the stereoisomers. A Mannich reaction with (/sup 2/H/sub 2/) methylene diacetate, diethyl ..cap alpha..-acetamido-..cap alpha..-dimethylamino(/sup 2/H/sub 2/)methylmalonate methiodide (15). Treatment of 15 with sodium benzylmercaptide gave diethyl ..cap alpha..-acetamido-..cap alpha..-benzylthio(/sup 2/H/sub 2/)methylmalonate, which was hydrolyzed with HCl to yield S-benzyl-DL-(..beta..,..beta..-/sup 2/H/sub 2/)cysteine or with DCl to afford S-benzyl-DL-(..cap alpha..,..beta..,..beta..,-/sup 2/H/sub 3/)cysteine. These compounds were resolved as before. The preparation of S-benzyl-DL-(..cap alpha..,..beta..,..beta..-/sup 2/H/sub 3/)cysteine required an efficient source of ethanol-d. This deuterated solvent was prepared in quantitative yield in 2 h from tetraethoxysilane, D/sub 2/O, and a catalytic amount of thionyl chloride. The protected deuterated amino acids were used in the preparation of several oxytocin analogues in which the specific deuteration appears in either the 1-hemicystine or the 6-hemicystine residues.

  14. Analysis of the Staphylococcus aureus capsule biosynthesis pathway in vitro: characterization of the UDP-GlcNAc C6 dehydratases CapD and CapE and identification of enzyme inhibitors.

    Science.gov (United States)

    Li, Wenjin; Ulm, Hannah; Rausch, Marvin; Li, Xue; O'Riordan, Katie; Lee, Jean C; Schneider, Tanja; Müller, Christa E

    2014-11-01

    Polysaccharide capsules significantly contribute to virulence of invasive pathogens, and inhibition of capsule biosynthesis may offer a valuable strategy for novel anti-infective treatment. We purified and characterized the enzymes CapD and CapE of the Staphylococcus aureus serotype 5 biosynthesis cluster, which catalyze the first steps in the synthesis of the soluble capsule precursors UDP-D-FucNAc and UDP-L-FucNAc, respectively. CapD is an integral membrane protein and was obtained for the first time in a purified, active form. A capillary electrophoresis (CE)-based method applying micellar electrokinetic chromatography (MEKC) coupled with UV detection at 260 nm was developed for functional characterization of the enzymes using a fused-silica capillary, electrokinetic injection, and dynamic coating with polybrene at pH 12.4. The limits of detection for the CapD and CapE products UDP-2-acetamido-2,6-dideoxy-α-D-xylo-hex-4-ulose and UDP-2-acetamido-2,6-dideoxy-β-L-arabino-hex-4-ulose, respectively, were below 1 μM. Using this new, robust and sensitive method we performed kinetic studies for CapD and CapE and screened a compound library in search for enzyme inhibitors. Several active compounds were identified and characterized, including suramin (IC50 at CapE 1.82 μM) and ampicillin (IC50 at CapD 40.1 μM). Furthermore, the cell wall precursors UDP-D-MurNAc-pentapeptide and lipid II appear to function as inhibitors of CapD enzymatic activity, suggesting an integrated mechanism of regulation for cell envelope biosynthesis pathways in S. aureus. Corroborating the in vitro findings, staphylococcal cells grown in the presence of subinhibitory concentrations of ampicillin displayed drastically reduced CP production. Our studies contribute to a profound understanding of the capsule biosynthesis in pathogenic bacteria. This approach may lead to the identification of novel anti-virulence and antibiotic drugs. Copyright © 2014 Elsevier GmbH. All rights reserved.

  15. Redox biology of Mycobacterium tuberculosis H37Rv: protein-protein interaction between GlgB and WhiB1 involves exchange of thiol-disulfide

    Directory of Open Access Journals (Sweden)

    Kishan KV Radha

    2009-01-01

    Full Text Available Abstract Background Mycobacterium tuberculosis, an intracellular pathogen encounters redox stress throughout its life inside the host. In order to protect itself from the redox onslaughts of host immune system, M. tuberculosis appears to have developed accessory thioredoxin-like proteins which are represented by ORFs encoding WhiB-like proteins. We have earlier reported that WhiB1/Rv3219 is a thioredoxin like protein of M. tuberculosis and functions as a protein disulfide reductase. Generally thioredoxins have many substrate proteins. The current study aims to identify the substrate protein(s of M. tuberculosis WhiB1. Results Using yeast two-hybrid screen, we identified alpha (1,4-glucan branching enzyme (GlgB of M. tuberculosis as a interaction partner of WhiB1. In vitro GST pull down assay confirmed the direct physical interaction between GlgB and WhiB1. Both mass spectrometry data of tryptic digests and in vitro labeling of cysteine residues with 4-acetamido-4' maleimidyl-stilbene-2, 2'-disulfonic acid showed that in GlgB, C95 and C658 are free but C193 and C617 form an intra-molecular disulfide bond. WhiB1 has a C37XXC40 motif thus a C40S mutation renders C37 to exist as a free thiol to form a hetero-disulfide bond with the cysteine residue of substrate protein. A disulfide mediated binary complex formation between GlgB and WhiB1C40S was shown by both in-solution protein-protein interaction and thioredoxin affinity chromatography. Finally, transfer of reducing equivalent from WhiB1 to GlgB disulfide was confirmed by 4-acetamido-4' maleimidyl-stilbene-2, 2'-disulfonic acid trapping by the reduced disulfide of GlgB. Two different thioredoxins, TrxB/Rv1471 and TrxC/Rv3914 of M. tuberculosis could not perform this reaction suggesting that the reduction of GlgB by WhiB1 is specific. Conclusion We conclude that M. tuberculosis GlgB has one intra-molecular disulfide bond which is formed between C193 and C617. WhiB1, a thioredoxin like protein

  16. Pseudomonas aeruginosa B-band lipopolysaccharide genes wbpA and wbpI and their Escherichia coli homologues wecC and wecB are not functionally interchangeable.

    Science.gov (United States)

    Burrows, L L; Pigeon, K E; Lam, J S

    2000-08-15

    The O antigen unit of Pseudomonas aeruginosa serotype O5 is a complex trisaccharide containing 2-acetamido-3-acetiminido-2, 3-dideoxy-beta-D-mannuronic acid, 2-acetimido-3-acetimido-2, 3-dideoxy-beta-D-mannuronic acid, and 2-acetimido-2, 6-deoxy-beta-D-galactosamine. Specific knockout mutations in the putative UDP-D-N-acetylglucosamine (UDP-D-GlcNAc) epimerase gene, wbpI, or the putative UDP-D-N-acetylmannosamine dehydrogenase gene, wbpA, resulted in strains that no longer produced B-band lipopolysaccharide, confirming the essential roles of these genes in B-band O antigen synthesis. Despite approximately 50% similarity of wbpI and wbpA to the Escherichia coli genes wecB (rffE) and wecC (rffD) involved in enterobacterial common antigen synthesis, cross-complementation experiments were not successful. These results imply that the P. aeruginosa UDP-D-GlcNAc precursor may be di-N-acetylated prior to further modification, preventing the E. coli enzymes from recognizing it as a substrate.

  17. UHPLC-Q-Orbitrap-HRMS-based global metabolomics reveal metabolome modifications in plasma of young women after cranberry juice consumption.

    Science.gov (United States)

    Liu, Haiyan; Garrett, Timothy J; Su, Zhihua; Khoo, Christina; Gu, Liwei

    2017-07-01

    Plasma metabolome in young women following cranberry juice consumption were investigated using a global UHPLC-Q-Orbitrap-HRMS approach. Seventeen female college students, between 21 and 29 years old, were given either cranberry juice or apple juice for three days using a cross-over design. Plasma samples were collected before and after juice consumption. Plasma metabolomes were analyzed using UHPLC-Q-Orbitrap-HRMS followed by orthogonal partial least squares-discriminant analyses (OPLS-DA). S-plot was used to identify discriminant metabolites. Validated OPLS-DA analyses showed that the plasma metabolome in young women, including both exogenous and endogenous metabolites, were altered following cranberry juice consumption. Cranberry juice caused increases of exogenous metabolites including quinic acid, vanilloloside, catechol sulfate, 3,4-dihydroxyphenyl ethanol sulfate, coumaric acid sulfate, ferulic acid sulfate, 5-(trihydroxphenyl)-gamma-valerolactone, 3-(hydroxyphenyl)proponic acid, hydroxyphenylacetic acid and trihydroxybenzoic acid. In addition, the plasma levels of endogenous metabolites including citramalic acid, aconitic acid, hydroxyoctadecanoic acid, hippuric acid, 2-hydroxyhippuric acid, vanilloylglycine, 4-acetamido-2-aminobutanoic acid, dihydroxyquinoline, and glycerol 3-phosphate were increased in women following cranberry juice consumption. The metabolic differences and discriminant metabolites observed in this study may serve as biomarkers of cranberry juice consumption and explain its health promoting properties in human. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Hydrogen abstraction by chlorine atom from amino acids: remarkable influence of polar effects on regioselectivity.

    Science.gov (United States)

    O'Reilly, Robert J; Chan, Bun; Taylor, Mark S; Ivanic, Sandra; Bacskay, George B; Easton, Christopher J; Radom, Leo

    2011-10-19

    Quantum chemistry computations have been used to investigate hydrogen-atom abstraction by chlorine atom from protonated and N-acetylated amino acids. The results are consistent with the decreased reactivity at the backbone α-carbon and adjacent side-chain positions that is observed experimentally. The individual effects of NH(3)(+), COOH, and NHAc substituents have been examined and reveal important insights. The NH(3)(+) group in isolation is found to be deactivating at the α-position, while the acetamido group is activating. For the COOH group, polar effects lead to a contrathermodynamic deactivation of the thermodynamically most favorable α-abstraction. In the N-acetylamino acid, the α-position is deactivated by the combined inductive effect of the substituents and the presence of an early transition structure, again overriding the greater thermodynamic stability of the α-centered radical product. Deactivation of the α-, β-, and γ-positions results in a peculiar stability for amino acids and peptides and their derivatives with respect to radical degradation.

  19. Development of an ion chromatography-inductively coupled plasma-mass spectrometry method to determine inorganic arsenic in liver from chickens treated with roxarsone.

    Science.gov (United States)

    Conklin, Sean D; Shockey, Nohora; Kubachka, Kevin; Howard, Karyn D; Carson, Mary C

    2012-09-19

    Roxarsone, (4-hydroxy-3-nitrophenyl)arsonic acid, is an arsenic-containing compound that has been approved as a feed additive for poultry and swine since the 1940s; however, little information is available regarding residual arsenic species present in edible tissues. We developed a novel method for the extraction and quantification of arsenic species in chicken liver. A strongly basic solution solubilized the liver, and ultrafiltration removed macromolecules and particulate material. Ion chromatography separated the species [arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, (4-hydroxy-3-aminophenyl)arsonic acid, (4-hydroxy-3-acetaminophenyl)arsonic acid, and roxarsone] in the extracts, which were then detected by inductively coupled plasma-mass spectrometry. The extraction oxidized most arsenite to arsenate. For fortification concentrations at 2 μg kg(-1) and above, recoveries ranged from 70 to 120%, with relative standard deviations from 7 to 34%. We detected roxarsone, its 3-amino and 3-acetamido metabolites, inorganic arsenic, and additional unknown arsenic species in livers from roxarsone-treated chickens. Both the originating laboratory and a second laboratory validated the method.

  20. Structural characterization of the extracellular polysaccharide from Vibrio cholerae O1 El-Tor.

    Directory of Open Access Journals (Sweden)

    Fitnat Yildiz

    Full Text Available The ability to form biofilms is important for environmental survival, transmission, and infectivity of Vibrio cholerae, the causative agent of cholera in humans. To form biofilms, V. cholerae produces an extracellular matrix composed of proteins, nucleic acids and a glycoconjugate, termed Vibrio exopolysaccharide (VPS. Here, we present the data on isolation and characterization of the polysaccharide part of the VPS (VPS-PS, which has the following structure: -4-α-GulpNAcAGly3OAc-(1-4-β-D-Glcp-(1-4-α-Glcp-(1-4-α-D-Galp-(1- where α-D-Glc is partially (∼20% replaced with α-D-GlcNAc. α-GulNAcAGly is an amide between 2-acetamido-2-deoxy-α-guluronic acid and glycine. Apparently, the polysaccharide is bound to a yet unidentified component, which gives it high viscosity and completely suppresses any NMR signals belonging to the sugar chains of the VPS. The only reliable method to remove this component at present is a treatment of the whole glycoconjugate with concentrated hydrochloric acid.

  1. Nanoconjugated NAP as a Potent and Periphery Selective Mu Opioid Receptor Modulator To Treat Opioid-Induced Constipation.

    Science.gov (United States)

    Xu, Guoyan G; Zolotarskaya, Olga Yu; Williams, Dwight A; Yuan, Yunyun; Selley, Dana E; Dewey, William L; Akbarali, Hamid I; Yang, Hu; Zhang, Yan

    2017-01-12

    Opioids are the mainstay for cancer and noncancer pain management. However, their use is often associated with multiple adverse effects. Among them, the most common and persistent one is probably opioid-induced constipation (OIC). Periphery selective opioid antagonists may alleviate the symptoms of OIC without compromising the analgesic effects of opioids. Recently our laboratories have identified one novel lead compound, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)acetamido]morphinan (NAP), as a peripherally selective mu opioid receptor ligand carrying subnanomolar affinity to the mu opioid receptor and over 100-folds of selectivity over both the delta and kappa opioid receptors, with reasonable oral availability and half-life, and potential to treat OIC. Nanoparticle-based drug delivery systems are now widely considered due to their technological advantages such as good stability, high carrier capacity, low therapeutic side effects, etc. Herein we report nanoparticle supported NAP as a potential candidate for OIC treatment with improved peripheral selectivity over the original lead compound NAP.

  2. Antituberculosis study of organotin(IV complexes: A review

    Directory of Open Access Journals (Sweden)

    Humaira Iqbal

    2015-12-01

    Full Text Available This review emphasized on the antituberculosis activity of organotin complexes. The astonishing antituberculosis activity of organotin complexes of mefenamic acid, 2-[(2,6-dimethylphenylamino]benzoic acid (HDMPA, and [bis(2,6-dimethylphenylamino]benzoic acid, NSAIDs from the carboxylic acid, oxicams family, meclofenamic acid or (N-(2,6-dichloro-m-tolylanthranilic acid, cinnamic acid, (Z-2-acetamido-3-phenylacrylic acid, 3-methyl-but-2-enoic acid, and 2,2-diphenylacetic acid is scrutinized using Mycobacterium tuberculosis H37Rv. It showed that there exists a beguiling, range of structural diversity for organotin moiety in all these complexes. Biologically active compounds should have available coordination positions at tin. Antituberculosis activity of organotin complexes is influenced by the nature of the ligand environment, organic groups attached to the tin, compound structure, toxicity, and potential mechanism of action; though generally, an MIC ≤ 1 μg ml−1 in a new compound class is considered a good lead. The results of complexes exhibited that triorganotin(IV complexes have superior antituberculosis activity as compared to diorganotin(IV complexes. It may be due to the fact that generally toxicity of the organotin compounds is associated with the organic ligand and the toxicity decreases with the order of tri > di > mono-organotins.

  3. A series of hybrid P450 BM3 enzymes with different catalytic activity in the light-initiated hydroxylation of lauric acid.

    Science.gov (United States)

    Tran, Ngoc-Han; Huynh, Ngoc; Chavez, Garrett; Nguyen, Angelina; Dwaraknath, Sudharsan; Nguyen, Thien-Anh; Nguyen, Maxine; Cheruzel, Lionel

    2012-10-01

    We have developed a series of hybrid P450 BM3 enzymes to perform the light-activated hydroxylation of lauric acid. These enzymes contain a Ru(II)-diimine photosensitizer covalently attached to single cysteine residues of mutant P450 BM3 heme domains. The library of hybrid enzymes includes four non-native single cysteine mutants (K97C, Q397C, Q109C and L407C). In addition, mutations around the heme active site, F87A and I401P, were inserted in the Q397C mutant. Two heteroleptic Ru(II) complexes, Ru(bpy)(2)phenA (1) and Ru(phen)(2)phenA (2) (bpy=bipyridine, phen=1,10-phenanthroline, and phenA=5-acetamido-1,10-phenanthroline), are used as photosensitizers. Upon visible light irradiation, the hybrid enzymes display various total turnover numbers in the hydroxylation of lauric acid, up to 140 for the L407C-1 mutant, a 16-fold increase compared to the F87A/Q397C-1 mutant. CO binding studies confirm the ability of the photogenerated Ru(I) compound to reduce the fraction of ferric high spin species present in the mutants upon substrate binding. Published by Elsevier Inc.

  4. Trypanocidal 1,3-arylene diketone bis(guanylhydrazone)s. Structure-activity relationships among substituted and heterocyclic analogues.

    Science.gov (United States)

    Ulrich, P; Cerami, A

    1984-01-01

    Based on the antitrypanosomal activity of 1,3-diacetylbenzene bis(guanylhydrazone) (4) and 2,6-diacetylpyridine bis(guanylhydrazone) (17), a number of substituted and heterocyclic 1,3-arylene diketone bis(guanylhydrazone)s were prepared and tested against Trypanosoma brucei infections in mice. A wide range of ED50 values was observed among 5-substituted derivatives of 4. The 5-amino analogue 5 and 5-acetamido analogue 6 were about twice as active as 4. 1,3,5-Triacetylbenzene tris(guanylhydrazone) (12) was about 9 times as active as 4 and was approximately one-half as active as the currently used trypanocide diminazene aceturate in this test system. Other 5-derivatives had activity equivalent to or less than that of the parent compound 4. Three new heterocyclic analogues were all less active than 2,6-diacetylpyridine derivative 17 and benzene derivative 4. Ring substitution ortho to the guanylhydrazone side chains was invariably detrimental to activity. Side-chain homologues 1,3-dipentanoylbenzene bis(guanylhydrazone) and 1,3-diacetylbenzene bis(2-imidazolin-2-ylhydrazone) were essentially inactive.

  5. Synthesis and antibacterial activities of novel pleuromutilin derivatives with a substituted pyrimidine moiety.

    Science.gov (United States)

    Yi, Yunpeng; Xu, Ximing; Liu, Yu; Xu, Shuijin; Huang, Xin; Liang, Jianping; Shang, Ruofeng

    2017-01-27

    The alarming growth of multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) has become a major global health hazard. Therefore, urgent demand for new antibiotics with a unique mechanism of action is very necessary. The present study reports the design, synthesis, and antibacterial studies of a series of novel pleuromutilin derivatives with substituted 6-amino pyrimidine moieties. Most of the tested compounds exhibited highly potent anti-MRSA or Staphylococcus aureus (S. aureus) activities. 14-O-[(4,6-Diamino -pyrimidine-2-yl) thioacetyl] mutilin (3) and 14-O-[(2-((3R)-3-Hydroxymethylpiperidine-1-yl)-acetamido-6-aminopyrimidine-2-yl) thioacetyl] mutilin (5h) were the most active compounds and showed higher antibacterial activities. Compound 3 displayed rapid bactericidal activity and affected bacterial growth with the same manner as tiamulin fumarate. Docking experiments for compounds 3 and 5h carried out on the peptidyl transferase center (PTC) of 23S rRNA provided the information about the binding model. In vivo mouse systemic infection experimental results confirmed the therapeutic efficacy of compound 3, with ED 50 of 4.22 mg/kg body weight against MRSA. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  6. Correlation of Solid State and Solution Coordination Numbers with Infrared Spectroscopy in Five-, Six-, and Eight-Coordinate Transition Metal Complexes of DOTAM.

    Science.gov (United States)

    Nagata, Maika K C T; Brauchle, Paul S; Wang, Sen; Briggs, Sarah K; Hong, Young Soo; Laorenza, Daniel W; Lee, Andrea G; Westmoreland, T David

    2016-08-16

    Three new DOTAM (1,4,7,10-tetrakis(acetamido)-1,4,7,10-tetraazacyclododecane) complexes have been synthesized and characterized by X-ray crystallography: [Co(DOTAM)]Cl 2 •3H 2 O, [Ni(DOTAM)]Cl 2 •4H 2 O, and [Cu(DOTAM)](ClO 4 ) 2 •H 2 O. Solid state and solution IR spectroscopic features for a series of [M(DOTAM)] 2+ complexes (M=Mn, Co, Cu, Ni, Ca, Zn) correlate with solid state and solution coordination numbers. [Co(DOTAM)] 2+ , [Ni(DOTAM)] 2+ , and [Zn(DOTAM)] 2+ are demonstrated to be six-coordinate in both the solid state and in solution, while [Mn(DOTAM)] 2+ and [Ca(DOTAM)] 2+ are eight-coordinate in the solid state and remain so in solution. [Cu(DOTAM)] 2+ , which is five-coordinate by X-ray crystallography, is shown to increase its coordination number in solution to six-coordinate.

  7. Studies of cadmium(II), lead(II), nickel(II), cobalt(II) and chromium(VI) sorption on extracellular polymeric substances produced by Rhodococcus opacus and Rhodococcus rhodochrous.

    Science.gov (United States)

    Dobrowolski, Ryszard; Szcześ, Aleksandra; Czemierska, Magdalena; Jarosz-Wikołazka, Anna

    2017-02-01

    The adsorption of Cd(II), Pb(II), Ni(II), Co(II) and Cr(VI) ions on the extracellular polymeric substances (EPS) obtained from bacterial strain Rhodococcus opacus and Rhodococcus rhodochrous was investigated by the static sorption method. Influence of pH, time and temperature were studied. It was found that the influence of the pH value and time of adsorption depends on the type of adsorbed ions. For all investigated systems an increase of temperature above 35°C reduces adsorption. However, the static sorption capacities values oscillate around 1.5mmol/g, independently of the type of the studied metal ions. The adsorption mechanism of studied metal ions onto the tested EPSs seems to be very complex and it is probably due to an electrostatic attraction, a surface complex formation and chemical interaction between the metal ions and the functional groups (mainly hydroxyl, acetamido or amino groups) of bacterial extracellular biopolymers. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. The Synthesis and Characterization of Tetrakis [(p - amino phenoxy) methyl] methane

    Science.gov (United States)

    Peng, Yongli; Zou, Qian

    2017-06-01

    In order to solve the shortcomings of the cured epoxy resin poor toughness, this paper proceeded from the structural design of curing agent to synthesize a special curing agent tetrakis [(p-aminophenoxy) methyl] methane which containing both Benzene ring and amino group. A Symmetric compound of tetrakis [(p - acetamidophenoxy) methyl] methane was prepared by using simple and easy to get pentaerythritoltetratosylate and acetaminophen for raw materials, after Williamson etherification reaction intermediates for synthesis of a symmetrical structure of the compound tetrakis [(p-acetamido phenoxy) methyl] methane, then hydrolysed under acidic conditions it can be tetrakis [(p-amino phenoxy) methyl] methane. The influence of reaction time, reaction temperature and reactant ratio to production yield of tetrakis [(p - acetamidophenoxy) methyl] methane was studied by orthogonal experiment of three factors and three levels, and get the optimal process parameters: the reaction time: 16 h, the reaction temperature: 170 °C, reactant ratio, 1:5. The Structure of tetrakis [(p - acetamidophenoxy) methyl] methane and tetrakis [(p-amino phenoxy) methyl] methane were characterized by infrared and 1H-NMR.

  9. p-aminohippurate transport in the airways: Role of Na sup + and HCO sub 3 -

    Energy Technology Data Exchange (ETDEWEB)

    Cloutier, M.M. (Univ. of Connecticut Health Center, Farmington (USA))

    1989-12-01

    The role of Na{sup +} and HCO{sub 3}- in the transport of p-aminohippurate (PAH) across the canine tracheal epithelium was investigated using Ussing chamber techniques and radiolabeled PAH. Under control conditions, net PAH absorption or a tendency toward net PAH absorption was observed. Neither amiloride (10(-4) M), furosemide (10(-3) M), ouabain (2 x 10(-4) M), nor Na+ substitution of the Ringer solution with choline had any effect on unidirectional PAH fluxes. When the Ringer solution was replaced with a HCO{sub 3}(-)-free solution, net PAH absorption was consistently observed. In HCO{sub 3}(-)-free experiments, unidirectional PAH absorptive fluxes were inhibited by mucosal addition of either of the stilbene derivatives, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS, 10(-4) M) or 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS, 10(-4) M). DIDS was more effective than SITS and was also effective in inhibiting PAH absorption in tissues bathed in Ringer solution. Submucosal DIDS or SITS had no effect on PAH fluxes either in HCO{sub 3}(-)-free or Ringer experiments. We conclude that PAH transport in canine tracheal epithelium occurs by a HCO{sub 3}(-)-PAH exchange process located on the luminal membrane. PAH transport is not Na{sup +} dependent but is inhibited by both DIDS and SITS.

  10. Identification of genes involved in the assembly and attachment of a novel flagellin N-linked tetrasaccharide important for motility in the archaeon Methanococcus maripaludis.

    Science.gov (United States)

    VanDyke, David J; Wu, John; Logan, Susan M; Kelly, John F; Mizuno, Shino; Aizawa, Shin-Ichi; Jarrell, Ken F

    2009-05-01

    Recently, the flagellin proteins of Methanococcus maripaludis were found to harbour an N-linked tetrasaccharide composed of N-acetylgalactosamine, di-acetylated glucuronic acid, an acetylated and acetamidino-modified mannuronic acid linked to threonine, and a novel terminal sugar [(5S)-2-acetamido-2,4-dideoxy-5-O-methyl-α-L-erythro-hexos-5-ulo-1,5-pyranose]. To identify genes involved in the assembly and attachment of this glycan, in-frame deletions were constructed in putative glycan assembly genes. Successful deletion of genes encoding three glycosyltransferases and an oligosaccharyltransferase (Stt3p homologue) resulted in flagellins of decreased molecular masses as evidenced by immunoblotting, indicating partial or completely absent glycan structures. Deletion of the oligosaccharyltransferase or the glycosyltransferase responsible for the transfer of the second sugar in the chain resulted in flagellins that were not assembled into flagella filaments, as evidenced by electron microscopy. Deletions of the glycosyltransferases responsible for the addition of the third and terminal sugars in the glycan were confirmed by mass spectrometry analysis of purified flagellins from these mutants. Although flagellated, these mutants had decreased motility as evidenced by semi-swarm plate analysis with the presence of each additional sugar improving movement capabilities.

  11. Photolytic destruction of endocrine disruptor atrazine in aqueous solution under UV irradiation: Products and pathways

    Energy Technology Data Exchange (ETDEWEB)

    Chen Cheng [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Yang Shaogui, E-mail: yangdlut@126.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Guo Yaping [College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032 (China); Sun Cheng, E-mail: envidean@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Gu Chenggang [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Xu Bin [School of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai (China)

    2009-12-30

    The ultraviolet (UV) photolysis of atrazine in aqueous solution was investigated at wavelength of 254 nm in this study. This paper was mainly focused on the identification of atrazine degradation intermediates by HPLC-MS/MS and its degradation mechanisms. The photodegradation products included the following seven classes: dechloro-hydroxylated products, chloro-dealkylated products, dechloro-dealkylated products, alkylic-oxidated products, delamination-hydroxylated products, olefinic products, and dechloro-hydrogenated products which were never reported in direct photolytic process, 4-isopropylamino-6-ethylamino-s-triazine (IEST), 4,6-dihydroxy-s-triazine (OOST). The main degradation products were 2-hydroxy-4-acetamido-6-ethylamino-s-triazine (OIET), 2-chloro-4-isopropyl-amino-6-methylamino-s-triazine (CIMT), 2-chloro-4,6-divinylamino-s-triazine (CVVT), 2-chloro-4-ethylamino-6-amino-s-triazine(CEAT), 2-methoxy-4-isopropyl-amino-6-methylamino-s-triazine (OIMT), 2-hydroxy-4-acetamindo-6-ethylamino-s-triazine (ODET), etc. Finally, the possible degradation mechanism was also proposed here.

  12. A comparative investigation of the metabolism of the herbicide glufosinate in cell cultures of transgenic glufosinate-resistant and non-transgenic oilseed rape (Brassica napus) and corn (Zea mays).

    Science.gov (United States)

    Ruhland, Monika; Engelhardt, Gabriele; Pawlizki, Karlheinz

    2002-10-01

    To obtain information on differences between the metabolic pathways of the herbicide glufosinate (trade names: BASTA, LIBERTY) in non-transgenic, glufosinate-sensitive plants and in transgenic, glufosinate-resistant plants, the metabolism of 14C-labeled glufosinate and its enantiomers L- and D-glufosinate was studied using cell cultures of oilseed rape and corn. Transformation of glufosinate in both sensitive and transgenic rape cells remained at a low rate of about 3-10% in contrast to corn cells, where 20% was transformed in sensitive and 43% in transgenic cells after 14 days of incubation, the rest remaining as unchanged glufosinate. In sensitive rape and corn cells the main metabolite was 4-methylphosphinico-2-oxo-butanoic acid (PPO) with 7.3 and 16.4%, respectively, together with low amounts of 3-methylphosphinicopropionic acid (MPP), 4-methylphosphinico-2-hydroxybutanoic acid (MHB), 4-methylphosphinicobutanoic acid (MPB) and 2-methylphosphinicoacetic acid (MPA). An additional metabolite formed in transgenic cell cultures was 2-acetamido-4-methylbutanoic acid (N-acetyl-L-glufosinate, NGA), which was formed at rates of 3.2% in rape and 16.1% in corn. A further minor metabolite, not yet identified, was detected in both cell types. The liberation of 0.2% 14CO2 indicates further metabolic steps prior to a limited mineralization in plant cell cultures. L-glufosinate was transformed into the same metabolites as the glufosinate racemate. D-glufosinate was not metabolized.

  13. Localization and characterization of acharan sulfate in the body of the giant African snail Achatina fulica.

    Science.gov (United States)

    Jeong, J; Toida, T; Muneta, Y; Kosiishi, I; Imanari, T; Linhardt, R J; Choi, H S; Wu, S J; Kim, Y S

    2001-12-01

    Acharan sulfate is a glycosaminoglycan (GAG), having the structure -->4)-2-acetamido-2-deoxy-alpha-D-glucopyranose(1-->4)-2-sulfo-alpha-L-idopyranosyluronic acid (1-->, isolated from the body of the giant African snail Achatina fulica. This GAG represents 3-5% of the dry weight of this snail's soft body tissues. Frozen sections and polyester wax sections of the snail's body were stained by Alcian blue-periodic acid-Schiff's reagent (PAS) to localize acharan sulfate. Alcian blue staining indicated that GAG was mainly secreted into the outer surface of the body from internal granules. A highly mucous material was collected and treated and the acharan sulfate was recovered by ethanol and cetyl pyridinium chloride precipitation. Crude acharan sulfate was purified by DEAE-Sephacel ion-exchange chromatography. Depolymerization of intact mucus and purified acharan sulfate fractions by heparin lyase II (heparitinase I) from Flavobacterium heparinum produced an unsaturated disaccharide as a major product, establishing the repeating unit of acharan sulfate. These results demonstrate that mucus in the granule and secreted to the outside of the body is composed entirely of acharan sulfate.

  14. A new mannose-specific lectin from daylily (Hemerocallis fulva L. rhizome: purification and properties

    Directory of Open Access Journals (Sweden)

    V. O. Antonyuk

    2013-04-01

    Full Text Available A new lectin was purified from the daylily (Hemerocallis fulva L. with the yield of approximately 10 mg per kg of fresh plant rhizome. The purification procedure was based on application of the affinity chromathography on the column with yeast mannan and the ion-exchange chromatography on the column with DEAE-Toyopearl. The lectin possessed low affinity for α-methyl-D-mannopyranoside, D-fructose, D-turanose and 2-acetamido-D-galactopyranose and hight affinity for the yeast mannan. The lectin bound with greatly less affinity for the mannose-containig glycoproteins, such as ovoalbumin, ovomucoid and horseradish peroxidase. According to the results of electrophoresis in 20% DSNa-PAGE, the lectin consists of subunits of 12 kDa molecular weight. According to the results of gel-chromatography on the Toyopearl HW-55, the lectin’s molecular weight is 48 kDa. It agglutinated rabbit erythrocytes very well, while rat and guinea-pig erythrocytes were agglutinated worse, and human erythrocytes were not agglutinated at all. Lectin’s dialysis against 1% EDTA or heating to 60 ºC for 60 min did not stop its hemagglutinating activity.

  15. Hyaluronan: from biomimetic to industrial business strategy.

    Science.gov (United States)

    Murano, Erminio; Perin, Danilo; Khan, Riaz; Bergamin, Massimo

    2011-04-01

    Hyaluronan (hyaluronic acid) is a naturally occurring polysaccharide of a linear repeating disaccharide unit consisting of beta-(1-->4)-linked D-glucopyranuronic acid and beta-(1-->3)-linked 2-acetamido-2-deoxy-D-glucopyranose, which is present in extracellular matrices, the synovial fluid of joints, and scaffolding that comprises cartilage. In its mechanism of synthesis, its size, and its physico-chemical properties, hyaluronan is unique amongst other glycosaminoglycans. The network-forming, viscoelastic and its charge characteristics are important to many biochemical properties of living tissues. It is an important pericellular and cell surface constituent; its interaction with other macromolecules such as proteins, participates in regulating cell behavior during numerous morphogenic, restorative, and pathological processes in the body. The knowledge of HA in diseases such as various forms of cancers, arthritis and osteoporosis has led to new impetus in research and development in the preparation of biomaterials for surgical implants and drug conjugates for targeted delivery. A concise and focused review on hyaluronan is timely. This review will cover the following important aspects of hyaluronan: (i) biological functions and synthesis in nature; (ii) current industrial production and potential biosynthetic processes of hyaluronan; (iii) chemical modifications of hyaluronan leading to products of commercial significance; and (iv) and the global market position and manufacturers of hyaluronan.

  16. Crystal Structure and Catalytic Mechanism of PglD from Campylobacter jejuni

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, N.; Imperiali, B

    2008-01-01

    The carbohydrate 2, 4-diacetamido-2, 4, 6-trideoxy-{alpha}-d-glucopyranose (BacAc2) is found in a variety of eubacterial pathogens. In Campylobacter jejuni, PglD acetylates the C4 amino group on UDP-2-acetamido-4-amino-2, 4, 6-trideoxy-a-d-glucopyranose (UDP-4-amino-sugar) to form UDP-BacAc2. Sequence analysis predicts PglD to be a member of the left-handed {Beta} helix family of enzymes. However, poor sequence homology between PglD and left-handed {Beta} helix enzymes with existing structural data precludes unambiguous identification of the active site. The co-crystal structures of PglD in the presence of citrate, acetyl coenzyme A, or the UDP-4-amino-sugar were solved. The biological assembly is a trimer with one active site formed between two protomers. Residues lining the active site were identified, and results from functional assays on alanine mutants suggest His-125 is critical for catalysis, whereas His-15 and His-134 are involved in substrate binding. These results are discussed in the context of implications for proteins homologous to PglD in other pathogens.

  17. The mechanism of fluid secretion in the rabbit pancreas studied by means of various inhibitors.

    Science.gov (United States)

    Kuijpers, G A; Van Nooy, I G; De Pont, J J; Bonting, S L

    1984-12-05

    In order to increase our understanding of the mechanism of pancreatic fluid secretion we have studied the effects of various transport inhibitors on this process in the isolated rabbit pancreas. In this preparation, a high rate of unstimulated fluid secretion occurs, which probably originates from the ductular cells. Inhibitory are ouabain, furosemide, bumetanide, piretanide, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) and acetazolamide, with their half-inhibitory concentrations: 2 X 10(-6) M (ouabain), 1.3 X 10(-3) M (furosemide), 2.2 X 10(-3) M (bumetanide and piretanide) and 1.4 X 10(-4) M (SITS). With acetazolamide a maximal inhibition of only 20% is found at 10(-3) M. Amiloride (10(-3) M) has no effect on pancreatic fluid secretion. The inhibitory effects on HCO-3 output are always larger and those on Cl- output lower than those on fluid secretion. The results suggest that the ouabain-sensitive (Na+ + K+)-ATPase system provides the energy for a Na+-gradient-driven Cl--HCO-3-exchange transport system, sensitive to the loop diuretics furosemide, bumetanide and piretanide and to SITS. This system would drive the transcellular transport of HCO-3 and secondarily that of cations, Cl- and water.

  18. Easy and Rapid Detection of Mumps Virus by Live Fluorescent Visualization of Virus-Infected Cells.

    Directory of Open Access Journals (Sweden)

    Tadanobu Takahashi

    Full Text Available Mumps viruses show diverse cytopathic effects (CPEs of infected cells and viral plaque formation (no CPE or no plaque formation in some cases depending on the viral strain, highlighting the difficulty in mumps laboratory studies. In our previous study, a new sialidase substrate, 2-(benzothiazol-2-yl-4-bromophenyl 5-acetamido-3,5-dideoxy-α-D-glycero-D-galacto-2-nonulopyranosidonic acid (BTP3-Neu5Ac, was developed for visualization of sialidase activity. BTP3-Neu5Ac can easily and rapidly perform histochemical fluorescent visualization of influenza viruses and virus-infected cells without an antiviral antibody and cell fixation. In the present study, the potential utility of BTP3-Neu5Ac for rapid detection of mumps virus was demonstrated. BTP3-Neu5Ac could visualize dot-blotted mumps virus, virus-infected cells, and plaques (plaques should be called focuses due to staining of infected cells in this study, even if a CPE was not observed. Furthermore, virus cultivation was possible by direct pick-up from a fluorescent focus. In conventional methods, visible appearance of the CPE and focuses often requires more than 6 days after infection, but the new method with BTP3-Neu5Ac clearly visualized infected cells after 2 days and focuses after 4 days. The BTP3-Neu5Ac assay is a precise, easy, and rapid assay for confirmation and titration of mumps virus.

  19. Pyrophen Produced by Endophytic Fungi Aspergillus sp Isolated from Piper crocatum Ruiz and Pav Exhibits Cytotoxic Activity and Induces S Phase Arrest in T47D Breast Cancer Cells.

    Science.gov (United States)

    Astuti, Puji; Erden, Willy; Wahyono; Wahyuono, Subagus; Hertiani, Triana

    2016-01-01

    Ethyl acetate extracts obtained from culture of endophytic fungi Aspergillus sp isolated from Piper crocatum Ruiz and Pav, have been shown to possess cytotoxic activity against T47D breast cancer cells. Investigations were here conducted to determine bioactive compounds responsible for the activity. Bioassay guided fractionation was employed to obtain active compounds. Structure elucidation was performed based on analysis of LC-MS, 1H-NMR, 13C-NMR, COSY, DEPT, HMQC, HMBC data. Cytotoxity assays were conducted in 96 well plates against T47D and Vero cell lines. Bioassay guided isolation and chemical investigation led to the isolation of pyrophen, a 4-methoxy-6-(1'-acetamido-2'-phenylethyl)-2H-pyran-2-one. Further analysis of its activity against T47D and Vero cells showed an ability to inhibit the growth of T47D cells with IC50 values of 9.2 μg/mL but less cytotoxicity to Vero cells with an IC50 of 109 μg/mL. This compound at a concentration of 400 ng/mL induced S-phase arrest in T47D cells.

  20. Acinetobacter baumannii isolate BAL_212 from Vietnam produces the K57 capsular polysaccharide containing a rarely occurring amino sugar N-acetylviosamine.

    Science.gov (United States)

    Kenyon, Johanna J; Kasimova, Anastasiya A; Shashkov, Alexander S; Hall, Ruth M; Knirel, Yuriy A

    2018-02-01

    The structures of capsular polysaccharides (CPSs) produced by different Acinetobacter baumannii strains have proven to be invaluable in confirming the role of specific genes in the synthesis of rare sugars through the correlation of genetic content at the CPS biosynthesis locus with sugars found in corresponding CPS structures. A module of four genes (rmlA, rmlB, vioA and vioB) was identified in the KL57 capsule biosynthesis gene cluster of A. baumannii isolate BAL_212 from Vietnam. These genes were predicted to direct the synthesis of 4-acetamido-4,6-dideoxy-d-glucose (N-acetylviosamine, d-Qui4NAc) and the K57 CPS was found to contain this monosaccharide. The K57 structure was determined and, in addition to d-Qui4NAc, included three N-acetylgalactosamine residues in the main chain, with a single glucose side branch. The KL57 gene cluster has not been found in any other A. baumannii genomes, but the rmlA-rmlB-vioA-vioB module is present in the KL119 gene cluster that would likely produce a d-Qui4NAc-containing CPS.

  1. Preparation and characterization of nanocomposite films from oil palm pulp nanocellulose/poly (Vinyl alcohol) by casting method.

    Science.gov (United States)

    Asad, Mohammad; Saba, Naheed; Asiri, Abdullah M; Jawaid, M; Indarti, Eti; Wanrosli, W D

    2018-07-01

    TEMPO-oxidize nanocellulose (TONC) suspension has been obtained from total chlorine free (TCF) oil palm empty-fruit-bunches (OPEFB) pulp using 4-acetamido-TEMPO (2,2,6,6-tetramethyl piperidin-1-oxyl) mediated oxidation with sodium hypochlorite and sodium bromide in water at 25 °C and pH 10. TONC suspension with varied content from 0.5 to 6% (w/w) reinforced polyvinyl alcohol (PVA) polymer based nanocomposite films were prepared by the casting method. The structural interaction between the TONC and PVA was characterized by the Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the 4% (w/w) TONC content reinforced nanocomposite exhibited the highest tensile strength and modulus with an increase of 122% and 291% respectively, compared to PVA while the elongation at break decreased about 42.7%. Thermal stability of PVA based nanocomposite films was improved after incorporation of TONC. Incorporation of TONC in PVA film increases its crystallinity due to strongly linking between the hydroxyl groups of materials however considerable decreases beyond 2 wt% loading are observed. TONC incorporation beyond 2 wt% also reduces the melting temperature peaks and enthalpy of nanocomposite films. FT-IR spectra, NMR and SEM indicate that there is interaction between the TONC and PVA. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Synthesis and Antimicrobial Activity of 2-[2-(2,6-dichloro phenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H)ones.

    Science.gov (United States)

    Patel, Nb; Patel, Jc; Barat, Gg

    2010-04-01

    A series of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H) ones 6a-m have been synthesized by the reaction of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-substituted phenylacrylamido-6,8-dibromoquinazolin-4(3H) ones 5a-m with hydrazine hydrate in the presence of glacial acetic acid. The chalcones 5a-m were prepared by the condensation of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-acetamido-6,8-dibromoquinazolin-4(3H)one 4 with different substituted aromatic aldehyde. The benzoxazinone 2 was synthesized from 2-[2-(2,6-dichlorophenyl)amino]phenyl acetyl chloride 1 on treatment with 3,5-dibromoanthranilic acid in pyridine, which on reaction with hydrazine hydrate and then on acetylation reaction yielded 4. The structures of these compounds have been elucidated by elemental analyses, IR, and NMR spectral data. The title compounds pyrazolyl-quinazolin-4(3H)ones 6a-m were evaluated for their antibacterial and antifungal activities in vitro.

  3. AB variant of infantile GM2 gangliosidosis: deficiency of a factor necessary for stimulation of hexosaminidase A-catalyzed degradation of ganglioside GM2 and glycolipid GA2.

    Science.gov (United States)

    Conzelmann, E; Sandhoff, K

    1978-08-01

    Human kidney extracts heated to 60 degrees and devoid of hexosaminidase activity (2-acetamido-2-deoxy-beta-D-glucoside acetamidodeoxyglucohydrolase EC 3.2.1.30) stimulate more than 20-fold the hexosaminidase A-catalyzed degradation of ganglioside GM2 and of glycolipid GA2, the neuronal storage compounds of GM2 gangliosidosis. The stimulating factor of this extract, which is labile at temperatures above 60 degrees, is also present in kidney extracts from patients with infantile GM2 gangliosidosis having a deficiency of hexosaminidase A (Tay-Sachs disease, variant B) and a deficiency of hexosaminidases A and B (variant 0). Evidence is presented that this factor is defective in the AB-variant of infantile GM2 gangliosidosis which is characterized by an accumulation of glycolipids GM2 and GA2 despite the fact that the degrading enzymes, hexosaminidases A and B, retain normal activity levels. Thus, variant AB is an example of a fatal lipid storage disease that is caused not by a defect of a degrading enzyme but rather by a defective factor necessary for the interaction of lipid substrates and the water-soluble hydrolase.

  4. Anti-inflammatory and antinociceptive evaluation of newly synthesized 4-(substituted ethanoyl amino-3-mercapto-5-(4-methoxy phenyl-1,2,4-triazoles

    Directory of Open Access Journals (Sweden)

    Neeraj Upmanyu

    2011-01-01

    of oedema especially 6k exhibiting a percentage of oedema inhibition of 40.28%, which was comparable to that of the standard drug indomethacin (62.50% at 10mg/kg dose. Among the compounds tested, compound 6k exhibited good anti-nociceptive activity in both methods used. Pethidine (20mg/kg body weight s.c is used as the standard drug. Conclusion: SAR of these synthesized compounds shows that substitution with heterocyclic moiety at C-2 of the acetamido group at position 4 of the 1,2,4-triazole produces appreciable activity as compared to substitution with aliphatic moieties since among all the synthesized compounds, the most active ones are 6f, 6i and 6k that have piperdine, 1-benzyl piperazine and morpholine group, respectively at C-2 of the acetamido group at position 4 of the 1,2,4-triazole.

  5. Characterization of a beta-N-acetylhexosaminidase and a beta-N-acetylglucosaminidase/beta-glucosidase from Cellulomonas fimi.

    Science.gov (United States)

    Mayer, Christoph; Vocadlo, David J; Mah, Melanie; Rupitz, Karen; Stoll, Dominik; Warren, R A J; Withers, Stephen G

    2006-07-01

    The gram-positive soil bacterium Cellulomonas fimi is shown to produce at least two intracellular beta-N-acetylglucosaminidases, a family 20 beta-N-acetylhexosaminidase (Hex20), and a novel family 3-beta-N-acetylglucosaminidase/beta-glucosidase (Nag3), through screening of a genomic expression library, cloning of genes and analysis of their sequences. Nag3 exhibits broad substrate specificity for substituents at the C2 position of the glycone: kcat/Km values at 25 degrees C were 0.066 s(-1) x mM(-1) and 0.076 s(-1) x mM(-1) for 4'-nitrophenyl beta-N-acetyl-D-glucosaminide and 4'-nitrophenyl beta-D-glucoside, respectively. The first glycosidase with this broad specificity to be described, Nag3, suggests an interesting evolutionary link between beta-N-acetylglucosaminidases and beta-glucosidases of family 3. Reaction by a double-displacement mechanism was confirmed for Nag3 through the identification of a glycosyl-enzyme species trapped with the slow substrate 2',4'-dinitrophenyl 2-deoxy-2-fluoro-beta-D-glucopyranoside. Hex20 requires the acetamido group at C2 of the substrate, being unable to cleave beta-glucosides, since its mechanism involves an oxazolinium ion intermediate. However, it is broad in its specificity for the D-glucosyl/D-galactosyl configuration of the glycone: Km and kcat values were 53 microM and 482.3 s(-1) for 4'-nitrophenyl beta-N-acetyl-D-glucosaminide and 66 microM and 129.1 s(-1) for 4'-nitrophenyl beta-N-acetyl-D-galactosaminide.

  6. Proton accumulation and ATPase activity in Golgi apparatus-enriched vesicles from rat liver

    International Nuclear Information System (INIS)

    Yeh, H.I.; van Rossum, G.D.

    1991-01-01

    We have studied the mechanism by which liver Golgi apparatus maintains the acidity of its contents, using a subcellular fraction from rat liver highly enriched in Golgi marker enzymes. Proton accumulation (measured by quenching of acridine-orange fluorescence) and anion-dependent ATPase were characterized and compared. Maximal ATPase and proton accumulation required ATP; GTP and other nucleotides gave 10% to 30% of maximal activity. Among anions, Cl- and Br- approximately doubled the activities; others were much less effective. Half-maximal increase of ATPase and H+ uptake required 55 mmol/L and 27 mmol/L Cl-, respectively. In predominantly chloride media, SCN- and NO3- markedly inhibited H+ uptake. Nitrate competitively inhibited both the chloride-dependent ATPase (apparent Ki 6 mmol/L) and proton uptake (apparent Ki 2 mmol/L). Nitrate and SCN- also inhibited uptake of 36Cl. Replacing K+ with Na+ had no effect on the initial rate of proton uptake but somewhat reduced the steady state attained. Replacement of K+ with NH4+ and choline reduced proton uptake without affecting ATPase. The ATPase and H+ uptake were supported equally well by Mg2+ or Mn2+. The ATPase was competitively inhibited by 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulfonic acid (apparent Ki 39 mumol/L). Other agents inhibiting both H+ uptake and ATPase were N-ethylmaleimide, N,N'-dicyclohexylcarbodiimide, chlorpromazine, diethylstilbestrol, Zn2+, Co2+ and Cu2+. In the Cl- medium, accumulated protons were released by ionophores at the relative rates, monensin = nigericin greater than valinomycin greater than carbonyl cyanide mchlorophenylhydrazone; the last of these also reduced ATPase activity. In the absence of Cl-, monensin and valinomycin both stimulated the ATPase. These results show a close association between ATPase activity and acidification of liver Golgi vesicles

  7. Evidence for carrier-mediated chloride/bicarbonate exchange in canalicular rat liver plasma membrane vesicles

    Energy Technology Data Exchange (ETDEWEB)

    Meier, P.J.; Knickelbein, R.; Moseley, R.H.; Dobbins, J.W.; Boyer, J.L.

    1985-04-01

    To determine whether anion exchangers might play a role in hepatic bile formation, the authors looked for the presence of Cl/sup -/:OH/sup -/ and Cl/sup -/:HCO3/sup -/ exchange in highly purified canalicular (c) and basolateral (bl) rat liver plasma membrane (LPM) vesicles. In cLPM vesicles, a pH gradient stimulated /sup 36/Cl- uptake twofold above values obtained during pH-equilibrated conditions. When 50 mM HCO3/sup -/ was also present inside the vesicles, the same pH gradient resulted in Cl/sup -/ uptake to levels fourfold above pH- and HCO3--equilibrated controls and two- to threefold above Cl- equilibrium. Initial rates of both pH and HCO3/sup -/ gradient-stimulated Cl/sup -/ uptake were completely inhibited by 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene (DIDS). A valinomycin-induced K/sup +/ diffusion potential (inside positive) also stimulated Cl/sup -/ uptake in cLPM, but this conductive Cl- pathway was insensitive to DIDS. The DIDS-sensitive, pH and HCO3- gradient-stimulated Cl/sup -/ uptake demonstrated: saturation with Cl/sup -/; partial inhibition by bumetanide (26%), furosemide (33%), probenecid (37%), and 4-acetamido-4'-isothiocyano-2,2'-disulfonic acid stilbene (49%); cis-inhibition by chloride and nitrate but not by sulfate and various organic anions, and independence from the membrane potential. These data demonstrate the presence of an electroneutral Cl/sup -/:OH/sup -/ and Cl/sup -/:HCO3/sup -/ exchanger in rat liver canalicular membranes that favors Cl/sup -/:HCO3/sup -/ exchange. In contrast, no evidence was found for the presence of a Cl/sup -/:HCO3/sup -/ (OH/sup -/) exchange system in blLPM vesicles.

  8. A potentiometric and spectrophotometric study on acid-base equilibria in ethanol-aqueous solution of acetazolamide and related compounds.

    Science.gov (United States)

    Chufán, E E; Suvire, F D; Enriz, R D; Pedregosa, J C

    1999-07-12

    Acid-base equilibria in ethanol-aqueous solution of 5-acetamido-1,3,4-thiadiazole-2-sulfonamide (acetazolamide, H(2)acm), 5-tertbutyloxycarbonylamido-1,3,4-thiadiazole-2-sulfonamide (B-H(2)ats), 5-amino-1,3,4-thiadiazole-2-sulfonamide (Hats) and 5-amino-1,3,4-thiadiazole-2-thiol (Hatm) at 25 degrees C, 0.15 mol dm(-3) ionic strength (NaNO(3)), have been investigated by potentiometry and UV spectrophotometry. The ionization constants were calculated with SUPERQUAD program from potentiometric measurements and by a method according to Edsall et al. using the mole fractions determined by complementary tri-stimulus colorimetry (CTS). The constants obtained by potentiometry were: B-H(2)ats, pk(a(1))=7.33(3) and pk(a(2))=9.27(1); Hats, pk(a(1))=2.51(3) and pk(a(2))=8.49(1); Hatm, pk(a(1))=1.92(1) and pk(a(2))=6.81(1); whereas the constants determined by spectrophotometry were: H(2)acm, pk(a(1))=7.78(1) and pk(a(2))=9.57(2); B-H(2)ats, pk(a(1))=7.71(2) and pk(a(2))=9.61(2); Hats, pk(a(1))=2.19(3) and pk(a(2))=8.61(2); Hatm, pk(a(2))=6.90(2). Theoretical calculations using MO semiempirical and ab-initio RHF/6-31G* computations for the compounds were also performed. It was possible to clarify the preferred deprotonation mechanism of acetazolamide and B-H(2)ats in which the first deprotonation takes place at the carbonamido group.

  9. LC-QTOF MS screening of more than 1,000 licit and illicit drugs and their metabolites in wastewater and surface waters from the area of Bogotá, Colombia.

    Science.gov (United States)

    Hernández, Félix; Ibáñez, María; Botero-Coy, Ana-María; Bade, Richard; Bustos-López, Martha Cristina; Rincón, Javier; Moncayo, Alejandro; Bijlsma, Lubertus

    2015-08-01

    A large screening of around 1,000 emerging contaminants, focused on licit and illicit drugs and their metabolites, has been made in urban wastewaters (both influent and effluent) and surface waters from the area of Bogotá, Colombia. After a simple generic solid-phase extraction (SPE) step with Oasis hydrophilic-lipophilic balanced (HLB) cartridges, analyses were made by ultra high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS) under MS(E) mode (sequential acquisition of mass spectra at low energy (LE) and high collision energy (HE)). Accurate mass measurements and the information provided by MS(E) on the presence of the (de)protonated molecule and fragment ions allowed the reliable identification of the compounds detected, even without reference standards being available in some cases (tentative identification). The compounds most frequently found were acetaminophen/paracetamol, carbamazepine and its dihydro-dihydroxylated metabolite, clarithromycin, diclofenac, ibuprofen, gemfibrozil, lincomycin, losartan, valsartan, the two metabolites of metamizole (4-acetamido-antipyrine and 4-formylamino-antipyrine), sucralose, and cocaine and its main metabolite benzoylecgonine. Caffeine, the sweetener saccharin, and two hydroxylated metabolites of losartan were tentatively identified in almost all samples analyzed. Pharmaceutical lidocaine was tentatively identified and subsequently confirmed with reference standard. For the first time, a general overview of the occurrence of drugs and their metabolites in the aquatic environment of Colombia has been reported. In the near future, target methodologies, typically based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), will need to be set up for accurate and sensitive quantification of the contaminants selected on the basis on the information provided in the present paper.

  10. Conformational analysis of the Sda determinant-containing tetrasaccharide and two mimics in aqueous solution by using 1H NMR ROESY spectroscopy in combination with MD simulations

    International Nuclear Information System (INIS)

    Blanco, Jose L. Jimenez; Rooijen, Johannes J.M. van; Erbel, Paul J.A.; Leeflang, Bas R.; Kamerling, Johannis P.; Vliegenthart, Johannes F.G.

    2000-01-01

    The conformational behaviour of the spacer-linked synthetic Sd a tetrasaccharide β-d-GalpNAc-(1 → 4)-[α-Neu5Ac-(2 → 3)]-β-d-Galp-(1 → 4)-β-d-GlcpNAc-(1 → O) (CH 2 ) 5 NH 2 (1) and the two mimics β-d-Galp-(1 → 4)-[α-Neu5Ac-(2 → 3)]-β-d-Galp-(1 → 4)-β-d-GlcpNAc-(1 → O)(CH 2 ) 5 NH 2 (2) and β-d-GlcpNAc-(1 → 4)-[α-Neu5Ac-(2 → 3)]-β-d-Galp-(1 → 4)-β-d-GlcpNAc-(1 → O) (CH 2 ) 5 NH 2 (3) were investigated by 1 H NMR spectroscopy in combination with molecular dynamics (MD) simulations in water. Experimental 2D 1 H ROESY cross-peak intensities (ROEs) of the tetrasaccharides were compared with calculated ROEs derived from MD trajectories using the CROSREL program. Analysis of these data indicated that the oligosaccharidic skeletons of the compounds 1-3 are rather rigid, especially the β-d-Hex(NAc)-(1 → 4)-[α-Neu5Ac-(2 → 3)]-β-d-Galp fragments. The α- Neu5-Ac-(2 → 3)-β-d-Galp linkage occurred in two different energy minima in the three-dimensional structure of the compounds 1-3 in aqueous solution. Experimental data and dynamics simulations supported the finding that the higher energy rotamer (CHEAT forcefield) was abundant in compounds 1 and 3 due to the existence of a hydrogen bond between the carboxyl group of the sialic acid and the acetamido group of the terminal monosaccharide (GalNAc or GlcNAc) unit. The conformational similarity between 1 and 3 leads to the suggestion that also their activities will be alike.

  11. A rapid and sensitive method for measuring N-acetylglucosaminidase activity in cultured cells.

    Directory of Open Access Journals (Sweden)

    Victor Mauri

    Full Text Available A rapid and sensitive method to quantitatively assess N-acetylglucosaminidase (NAG activity in cultured cells is highly desirable for both basic research and clinical studies. NAG activity is deficient in cells from patients with Mucopolysaccharidosis type IIIB (MPS IIIB due to mutations in NAGLU, the gene that encodes NAG. Currently available techniques for measuring NAG activity in patient-derived cell lines include chromogenic and fluorogenic assays and provide a biochemical method for the diagnosis of MPS IIIB. However, standard protocols require large amounts of cells, cell disruption by sonication or freeze-thawing, and normalization to the cellular protein content, resulting in an error-prone procedure that is material- and time-consuming and that produces highly variable results. Here we report a new procedure for measuring NAG activity in cultured cells. This procedure is based on the use of the fluorogenic NAG substrate, 4-Methylumbelliferyl-2-acetamido-2-deoxy-alpha-D-glucopyranoside (MUG, in a one-step cell assay that does not require cell disruption or post-assay normalization and that employs a low number of cells in 96-well plate format. We show that the NAG one-step cell assay greatly discriminates between wild-type and MPS IIIB patient-derived fibroblasts, thus providing a rapid method for the detection of deficiencies in NAG activity. We also show that the assay is sensitive to changes in NAG activity due to increases in NAGLU expression achieved by either overexpressing the transcription factor EB (TFEB, a master regulator of lysosomal function, or by inducing TFEB activation chemically. Because of its small format, rapidity, sensitivity and reproducibility, the NAG one-step cell assay is suitable for multiple procedures, including the high-throughput screening of chemical libraries to identify modulators of NAG expression, folding and activity, and the investigation of candidate molecules and constructs for applications in

  12. High-resolution MS and MS(n) investigation of ozone oxidation products from phenazone-type pharmaceuticals and metabolites.

    Science.gov (United States)

    Favier, Maxime; Dewil, Raf; Van Eyck, Kwinten; Van Schepdael, Ann; Cabooter, Deirdre

    2015-10-01

    Phenazone-type pharmaceuticals, such as aminopyrine, metamizole, phenazone and propyphenazone, are widely used analgesics that have been detected in wastewater treatment plant effluents in μg L(-1) concentrations. Acetamido antipyrine (AAA) and formyl aminoantipyrine (FAA) - the main metabolites of aminopyrine and metamizole - have also been detected in sub μg L(-1) concentrations in environmental water bodies and in resources used to produce drinking water, suggesting their highly persistent character. In this study phenazone, propyphenazone, AAA and FAA were treated with ozone under laboratory conditions and 17 degradation products were identified by an elucidation approach based on high-resolution mass spectrometry (LTQ Orbitrap). Typical oxidation of carbon-carbon double bonds by ozone was observed among other mechanisms of ring opening. It was demonstrated that reactivity of these compounds with ozone is high (rate constants kO3 ranging from 6.5×10(4) to 2.4×10(6) M(-1) s(-1)). The toxicity of the degradation products from ozonation was estimated by quantitative structure-activity relationships (QSAR). It was shown that, when the carbon-carbon double bond is partially oxidized to an epoxy, the toxicity towards fish and daphnids is higher than that of the parent compound. By further oxidizing the molecules, a common degradation product - 1-acetyl-1-methyl-2-phenylhydrazide (AMPH) - was also found to be more toxic than its parent compounds, which is of concern since this compound has previously been reported in environmental waters. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Identification of a gene involved in the biosynthesis pathway of the terminal sugar of the archaellin N-linked tetrasaccharide in Methanococcus maripaludis.

    Science.gov (United States)

    Ding, Yan; Jones, Gareth M; Brimacombe, Cedric; Uchida, Kaoru; Aizawa, Shin-Ichi; Logan, Susan M; Kelly, John F; Jarrell, Ken F

    2016-01-01

    In Methanococcus maripaludis, the three archaellins which comprise the archaellum are modified at multiple sites with an N-linked tetrasaccharide with the structure of Sug-4-β-ManNAc3NAmA6Thr-4-β-GlcNAc3NAcA-3-β-GalNAc, where Sug is a unique sugar (5S)-2-acetamido-2,4-dideoxy-5-O-methyl-L-erythro-hexos-5-ulo-1,5-pyranose, so far found exclusively in this species. In this study, a six-gene cluster mmp1089-1094, neighboring one of the genomic regions already known to contain genes involved with the archaellin N-glycosylation pathway, was examined for its potential involvement in the archaellin N-glycosylation or sugar biosynthesis pathway. The co-transcription of these six genes was demonstrated by RT-PCR. Mutants carrying an in-frame deletion in mmp1090, mmp1091 or mmp1092 were successfully generated. The Δmmp1090 deletion mutant was archaellated when examined by electron microscopy and mass spectrometry analysis of purified archaella showed that the archaellins were modified with a truncated N-glycan in which the terminal sugar residue and the threonine linked to the third sugar residue were missing. Both gene annotation and bioinformatic analyses indicate that MMP1090 is a UDP-glucose 4-epimerase, suggesting that the unique terminal sugar of the archaellin N-glycan might be synthesised from UDP-glucose or UDP-N-acetylglucosamine with an essential early step in synthesis catalysed by MMP1090. In contrast, no detectable phenotype related to archaellin glycosylation was observed in mutants deleted for either mmp1091 or mmp1092 while attempts to delete mmp1089, mmp1093 and mmp1094 were unsuccessful. Based on its demonstrated involvement in the archaellin N-glycosylation pathway, we designated mmp1090 as aglW.

  14. Identification of genes involved in the acetamidino group modification of the flagellin N-linked glycan of Methanococcus maripaludis.

    Science.gov (United States)

    Jones, Gareth M; Wu, John; Ding, Yan; Uchida, Kaoru; Aizawa, Shin-Ichi; Robotham, Anna; Logan, Susan M; Kelly, John; Jarrell, Ken F

    2012-05-01

    N-linked glycosylation of protein is a posttranslational modification found in all three domains of life. The flagellin proteins of the archaeon Methanococcus maripaludis are known to be modified with an N-linked tetrasaccharide consisting of N-acetylgalactosamine (GalNAc), a diacetylated glucuronic acid (GlcNAc3NAc), an acetylated and acetamidino-modified mannuronic acid with a substituted threonine group (ManNAc3NAmA6Thr), and a novel terminal sugar residue [(5S)-2-acetamido-2,4-dideoxy-5-O-methyl-α-L-erythro-hexos-5-ulo-1,5-pyranose]. To identify genes involved in biosynthesis of the component sugars of this glycan, three genes, mmp1081, mmp1082, and mmp1083, were targeted for in-frame deletion, based on their annotation and proximity to glycosyltransferase genes known to be involved in assembly of the glycan. Mutants carrying a deletion in any of these three genes remained flagellated and motile. A strain with a deletion of mmp1081 had lower-molecular-mass flagellins in Western blots. Mass spectrometry of purified flagella revealed a truncated glycan with the terminal sugar absent and the threonine residue and the acetamidino group missing from the third sugar. No glycan modification was seen in either the Δmmp1082 or Δmmp1083 mutant grown in complex Balch III medium. However, a glycan identical to the Δmmp1081 glycan was observed when the Δmmp1082 or Δmmp1083 mutant was grown under ammonia-limited conditions. We hypothesize that MMP1082 generates ammonia and tunnels it through MMP1083 to MMP1081, which acts as the amidotransferase, modifying the third sugar residue of the M. maripaludis glycan with the acetamidino group.

  15. Design, synthesis, and biological evaluation of enantiomeric beta-N-acetylhexosaminidase inhibitors LABNAc and DABNAc as potential agents against Tay-Sachs and Sandhoff disease.

    Science.gov (United States)

    Rountree, J S Shane; Butters, Terry D; Wormald, Mark R; Boomkamp, Stephanie D; Dwek, Raymond A; Asano, Naoki; Ikeda, Kyoko; Evinson, Emma L; Nash, Robert J; Fleet, George W J

    2009-03-01

    N-Acetylhexosaminidases are of considerable importance in mammals and are involved in various significant biological processes. In humans, deficiencies of these enzymes in the lysosome, resulting from inherited genetic defects, cause the glycolipid storage disorders Tay-Sachs and Sandhoff diseases. One promising therapy for these diseases involves the use of beta-N-acetylhexosaminidase inhibitors as chemical chaperones to enhance the enzyme activity above sub-critical levels. Herein we describe the synthesis and biological evaluation of a potent inhibitor, 2-acetamido-1,4-imino-1,2,4-trideoxy-L-arabinitol (LABNAc), in a high-yielding 11-step procedure from D-lyxonolactone. The N-benzyl and N-butyl analogues were also prepared and found to be potent inhibitors. The enantiomers DABNAc and NBn-DABNAc were synthesised from L-lyxonolactone, and were also evaluated. The L-iminosugar LABNAc and its derivatives were found to be potent noncompetitive inhibitors of some beta-N-acetylhexosaminidases, while the D-iminosugar DABNAc and its derivatives were found to be weaker competitive inhibitors. These results support previous work postulating that D-iminosugar mimics inhibit D-glycohydrolases competitively, and that their corresponding L-enantiomers show noncompetitive inhibition of these enzymes. Molecular modelling studies confirm that the spatial organisation in enantiomeric inhibitors leads to a different overlay with the monosaccharide substrate. Initial cell-based studies suggest that NBn-LABNAc can act as a chemical chaperone to enhance the deficient enzyme's activity to levels that may cause a positive pharmacological effect. LABNAc, NBn-LABNAc, and NBu-LABNAc are potent and selective inhibitors of beta-N-acetylhexosaminidase and may be useful as therapeutic agents for treating adult Tay-Sachs and Sandhoff diseases.

  16. Purification of Keratan Sulfate-endogalactosidase and its action on keratan sulfates of different origin.

    Science.gov (United States)

    Nakazawa, K; Suzuki, S

    1975-02-10

    A glycosidase which attacks corneal keratan sulfate was purified from extracts of Pseudomonas sp. IFO-13309. When corneal keratan sulfate was degraded by the purified enzyme, Sephadex G-50 chromatography indicated the presence of a number of oligosaccharides differing in size and sulfate content. The characterization of two major fractions of the oligosaccharides indicated that the point of enzyme attack is limited to the endo-beta-D-galactoside bonds in which nonsulfated D-galactose residues participate. The enzyme, unlike ordinary exo-beta-D-galactosidases, did not catalyze the hydrolysis of phenyl beta-D-galactoside. Moreover, beta-D-galactosyl-(1 leads to 3)-2-acetamido-2-deoxy-beta-D-glucosyl-(1 leads to 3)-beta-D-galactosyl-(1 leads to 4)-D-glucose ("lacto-N-tetraose") was completely refractory to the action of this enzyme, suggesting that a structure of the type, X-(1 leads to 3)-beta-D-galactosyl-(1 leads to 4)-Y, is not the only specificity-determining factor, i.e. neighboring sugars, X and Y, or even larger portions of substrate molecule must have an important effect. Compared with corneal keratan sulfate, keratan sulfates from human nucleus pulposus and shark cartilage were attacked at lower rates with a resultant production of oligosaccharides of relatively large size. The result is in agreement with the view that considerable variations exist in the structure of keratan sulfates of different origin, and further suggests that the enzyme may serve as a useful reagent in studying these variations.

  17. The chitin-binding domain of a GH-18 chitinase from Vibrio harveyi is crucial for chitin-chitinase interactions.

    Science.gov (United States)

    Suginta, Wipa; Sirimontree, Paknisa; Sritho, Natchanok; Ohnuma, Takayuki; Fukamizo, Tamo

    2016-12-01

    Vibrio harveyi chitinase A (VhChiA) is a GH-18 glycosyl hydrolase with a structure containing three distinct domains: i) the N-terminal chitin-binding domain; ii) the (α/β) 8 TIM barrel catalytic domain; and iii) the α+β insertion domain. In this study, we cloned the gene fragment encoding the chitin-binding domain of VhChiA, termed ChBD Vh ChiA . The recombinant ChBD Vh ChiA was heterologously expressed in E. coli BL21 strain Tuner(DE3)pLacI host cells, and purified to homogeneity. CD measurements suggested that ChBD Vh ChiA contained β-sheets as major structural components and fluorescence spectroscopy showed that the protein domain was folded correctly, and suitable for functional characterization. Chitin binding assays showed that ChBD Vh ChiA bound to both α- and β-chitins, with the greatest affinity for β-colloidal chitin, but barely bound to polymeric chitosan. These results identified the tandem N-acetamido functionality on chitin chains as the specific sites of enzyme-substrate interactions. The binding affinity of the isolated domain was significantly lower than that of intact VhChiA, suggesting that the catalytic domain works synergistically with the chitin-binding domain to guide the polymeric substrate into the substrate binding cleft. These data confirm the physiological role of the chitin-binding domain of the marine bacterial GH-18 chitinase A in chitin-chitinase interactions. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Homologs of the Rml Enzymes from Salmonella enterica Are Responsible for dTDP-β-l-Rhamnose Biosynthesis in the Gram-Positive Thermophile Aneurinibacillus thermoaerophilus DSM 10155

    Science.gov (United States)

    Graninger, Michael; Kneidinger, Bernd; Bruno, Katharina; Scheberl, Andrea; Messner, Paul

    2002-01-01

    The glycan chains of the surface layer (S-layer) glycoprotein from the gram-positive, thermophilic bacterium Aneurinibacillus (formerly Bacillus) thermoaerophilus strain DSM 10155 are composed of l-rhamnose- and d-glycero-d-manno-heptose-containing disaccharide repeating units which are linked to the S-layer polypeptide via core structures that have variable lengths and novel O-glycosidic linkages. In this work we investigated the enzymes involved in the biosynthesis of thymidine diphospho-l-rhamnose (dTDP-l-rhamnose) and their specific properties. Comparable to lipopolysaccharide O-antigen biosynthesis in gram-negative bacteria, dTDP-l-rhamnose is synthesized in a four-step reaction sequence from dTTP and glucose 1-phosphate by the enzymes glucose-1-phosphate thymidylyltransferase (RmlA), dTDP-d-glucose 4,6-dehydratase (RmlB), dTDP-4-dehydrorhamnose 3,5-epimerase (RmlC), and dTDP-4-dehydrorhamnose reductase (RmlD). The rhamnose biosynthesis operon from A. thermoaerophilus DSM 10155 was sequenced, and the genes were overexpressed in Escherichia coli. Compared to purified enterobacterial Rml enzymes, the enzymes from the gram-positive strain show remarkably increased thermostability, a property which is particularly interesting for high-throughput screening and enzymatic synthesis. The closely related strain A. thermoaerophilus L420-91T produces d-rhamnose- and 3-acetamido-3,6-dideoxy-d-galactose-containing S-layer glycan chains. Comparison of the enzyme activity patterns in A. thermoaerophilus strains DSM 10155 and L420-91T for l-rhamnose and d-rhamnose biosynthesis indicated that the enzymes are differentially expressed during S-layer glycan biosynthesis and that A. thermoaerophilus L420-91T is not able to synthesize dTDP-l-rhamnose. These findings confirm that in each strain the enzymes act specifically on S-layer glycoprotein glycan formation. PMID:12147463

  19. Expression of Functional Human Sialyltransferases ST3Gal1 and ST6Gal1 in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Maria Elena Ortiz-Soto

    Full Text Available Sialyltransferases (STs are disulfide-containing, type II transmembrane glycoproteins that catalyze the transfer of sialic acid to proteins and lipids and participate in the synthesis of the core structure oligosaccharides of human milk. Sialic acids are found at the outermost position of glycostructures, playing a key role in health and disease. Sialylation is also essential for the production of recombinant therapeutic proteins (RTPs. Despite their importance, availability of sialyltransferases is limited due to the low levels of stable, soluble and active protein produced in bacterial expression systems, which hampers biochemical and structural studies on these enzymes and restricts biotechnological applications. We report the successful expression of active human sialyltransferases ST3Gal1 and ST6Gal1 in commercial Escherichia coli strains designed for production of disulfide-containing proteins. Fusion of hST3Gal1 with different solubility enhancers and substitution of exposed hydrophobic amino acids by negatively charged residues (supercharging-like approach were performed to promote solubility and folding. Co-expression of sialyltransferases with the chaperon/foldases sulfhydryl oxidase, protein disulfide isomerase and disulfide isomerase C was explored to improve the formation of native disulfide bonds. Active sialyltransferases fused with maltose binding protein (MBP were obtained in sufficient amounts for biochemical and structural studies when expressed under oxidative conditions and co-expression of folding factors increased the yields of active and properly folded sialyltransferases by 20%. Mutation of exposed hydrophobic amino acids increased recovery of active enzyme by 2.5-fold, yielding about 7 mg of purified protein per liter culture. Functionality of recombinant enzymes was evaluated in the synthesis of sialosides from the β-d-galactoside substrates lactose, N-acetyllactosamine and benzyl 2-acetamido-2-deoxy-3-O-(β-d-galactopyranosyl-α-d-galactopyranoside.

  20. In vitro synthesis of intermediates involved in the assembly of enterobacterial common antigen (ECA)

    International Nuclear Information System (INIS)

    Barr, K.; Wolski, S.; Kroto, J.; Rick, P.D.

    1986-01-01

    ECA is a cell surface antigen found in all bacteria belonging to the family Enterobacteriaceae. The serological specificity of ECA is determined by a linear heteropolysaccharide comprised of trisaccharide repeat units; the component sugars are N-acetyl-D-glucosamine (GlcNAc), N-acetyl-D-mannosaminuronic acid (ManNAcUA), and 4-acetamido-D-fucose (Fuc4NAc). In vivo studies have suggested that GlcNAc-pyrophosphorylundecaprenol (GlcNAc-PP-lipid) is an intermediate in ECA synthesis. More recently, they have demonstrated UDP-GlcNAc:undecaprenylphosphate GlcNAc-1-phosphate transferase activity in cell envelope preparations of E. coli. Radioactivity from UDP-[ 3 H]Glc-NAc was incorporated into endogenous lipid acceptor, and the labeled product was characterized as GlcNAc-PP-lipid (lipid I). Transferase activity was inhibited by tunicamycin and UMP, but it was unaffected by UDP. The reaction was reversible, and the synthesis of UDP-[ 3 H]GlcNAc from UMP and [ 3 H]GlcNAc-PP-lipid was also sensitive to tunicamycin. The simultaneous addition of UDP-[ 14 C]ManNAcUA and UDP-[ 3 H]GlcNAc to cell envelope preparations resulted in the synthesis of a more polar lipid (lipid II) that contained both labeled sugars in equimolar amounts. Synthesis of lipid II was dependent on prior synthesis of lipid I. Accordingly, [ 3 H]GlcNAc-PP-lipid that had been synthesized in vivo served as an acceptor in vitro of ManNAcUA residues from UDP-ManNAcUA. Lipid II has been tentatively identified as ManNAcUA-GlcNAc-pyrophosphorylundecaprenol

  1. In vitro synthesis of a lipid-linked trisaccharide involved in synthesis of enterobacterial common antigen

    International Nuclear Information System (INIS)

    Barr, K.; Nunes-Edwards, P.; Rick, P.D.

    1989-01-01

    The heteropolysaccharide chains of enterobacterial common antigen (ECA) are made up of linear trisaccharide repeat units with the structure----3)-alpha-D-Fuc4NAc-(1----4)- beta-D-ManNAcA-(1----4)-alpha-D-GlcNAc-(1----, where Fuc4NAc is 4-acetamido-4,6-dideoxy-D-galactose, ManNAcA is N-acetyl-D-mannosaminuronic acid, and GlcNAc is N-acetyl-D-glucosamine. The assembly of these chains involves lipid-linked intermediates, and both GlcNAc-pyrophosphorylundecaprenol (lipid I) and ManNAcA-GlcNAc-pyrophosphorylundecaprenol (lipid II) are intermediates in ECA biosynthesis. In this study we demonstrated that lipid II serves as the acceptor of Fuc4NAc residues in the assembly of the trisaccharide repeat unit of ECA chains. Incubation of Escherichia coli membranes with UDP-GlcNAc, UDP-[14C]ManNAcA, and TDP-[3H]Fuc4NAc resulted in the synthesis of a radioactive glycolipid (lipid III) that contained both [14C]ManNAcA and [3H]Fuc4NAc. The oligosaccharide moiety of lipid III was identified as a trisaccharide by gel-permeation chromatography, and the in vitro synthesis of lipid III was dependent on prior synthesis of lipids I and II. Accordingly, the incorporation of [3H]Fuc4NAc into lipid III from the donor TDP-[3H]Fuc4NAc was dependent on the presence of both UDP-GlcNAc and UDP-ManNAcA in the reaction mixtures. In addition, the in vitro synthesis of lipid III was abolished by tunicamycin. Direct conversion of lipid II to lipid III was demonstrated in two-stage reactions in which membranes were initially incubated with UDP-GlcNAc and UDP-[14C]ManNAcA to allow the synthesis of radioactive lipid II

  2. Transferred nuclear Overhauser enhancement experiments show that the monoclonal antibody strep 9 selects a local minimum conformation of a Streptococcus group A trisaccharide-hapten.

    Science.gov (United States)

    Weimar, T; Harris, S L; Pitner, J B; Bock, K; Pinto, B M

    1995-10-17

    Transferred nuclear Overhauser enhancement (TRNOE) experiments have been performed to investigate the bound conformation of the trisaccharide repeating unit of the Streptococcus Group A cell-wall polysaccharide. Thus, the conformations of propyl 3-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-2-O-(alpha-L-rhamnopyran osyl)- alpha-L-rhamnopyranoside [C(A')B] (1) as a free ligand and when complexed to the monoclonal antibody Strep 9 were examined. Improved insights about the conformational preferences of the glycosidic linkages of the trisaccharide ligand showed that the free ligand populates various conformations in aqueous solution, thus displaying relatively flexible behavior. The NOE HNAc-H2A', which was not detected in previous work, accounts for a conformation at the beta-(1-->3) linkage with a phi angle of approximately 180 degrees. Observed TRNOEs for the complex are weak, and their analysis was further complicated by spin diffusion. With the use of transferred rotating-frame Overhauser enhancement (TRROE) experiments, the amount of spin diffusion was assessed experimentally, proving that all of the observed long-range TRNOEs arose through spin diffusion. Four interglycosidic distances, derived from the remaining TRNOEs and TRROEs, together with repulsive constraints, derived from the absence of TRROE effects, were used as input parameters in simulated annealing and molecular mechanics calculations to determine the bound conformation of the trisaccharide. Complexation by the antibody results in the selection of one defined conformation of the carbohydrate hapten. This bound conformation, which is a local energy minimum on the energy maps calculated for the trisaccharide ligand, shows only a change from a +gauche to a -gauche orientation at the psi angle of the alpha-(1-->2) linkage when compared to the global minimum conformation. The results infer that the bound conformation of the Streptococcus Group A cell-wall polysaccharide is different from its

  3. Simple and general procedure for the synthesis of semi-rigid chelating agents for radiometal complexation studies and its application to semi-rigid functionalised ligands (BCA) synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Loussouarn, A.; Faivre-Chauvet, A.; Chatal, J.-F.; Gestin, J.-F. [INSERM, Nantes (France). Inst. de Biologie

    1999-07-01

    Immunotherapy with radiolabeled antibodies should allow fairly specific targeting of certain cancers. However, iodine-131 may not be the best isotope for tumour therapy because of its limited specific activity, low beta-energy, relatively long half-life and strong gamma emission. Another approach to improve therapeutic efficacy is the use of replacement isotopes with better physical properties. Chelators that can hold radiometals with high stability under physiological conditions are essential to avoid excessive radiation damage to non-target cells. Moreover, the development of new bifunctional chelating agents is essential for this purpose. Accordingly, our efforts have been directed, for several years, to the synthesis of original chelating agents likely to form stable complexes in vivo with the numerous potential candidates for such applications. The stability of a non-macrocyclic ligand can be favourably influenced by the preorganization of the open chain. In fact, a semi-rigid structure such as that of trans-1,2-diaminocyclohexane limits the rotation of the ethylene bridge, so that the purpose of the cyclohexane design is to preorient the four pendent arms in a skew position. Therefore, we have developed a new simple and efficient synthesis pathway from trans-1,2-diaminocyclohexane to provide access to a new class of semi-rigid chelating agents. This same reactional scheme will be apply to our reactional intermediary, (1R{sup *}, 2R{sup *}, 4S{sup *})-4-acetamido-1,2-diaminocyclohexane dihydrochloride, which will allow the synthesis of these same chelating agents, though functionalised back of the cycle by a termination allowed coupling to an antibody or any other biological substance such as a hapten. (orig.)

  4. Simple and general procedure for the synthesis of semi-rigid chelating agents for radiometal complexation studies and its application to semi-rigid functionalised ligands (BCA) synthesis

    International Nuclear Information System (INIS)

    Loussouarn, A.; Faivre-Chauvet, A.; Chatal, J.-F.; Gestin, J.-F.

    1999-01-01

    Immunotherapy with radiolabeled antibodies should allow fairly specific targeting of certain cancers. However, iodine-131 may not be the best isotope for tumour therapy because of its limited specific activity, low beta-energy, relatively long half-life and strong gamma emission. Another approach to improve therapeutic efficacy is the use of replacement isotopes with better physical properties. Chelators that can hold radiometals with high stability under physiological conditions are essential to avoid excessive radiation damage to non-target cells. Moreover, the development of new bifunctional chelating agents is essential for this purpose. Accordingly, our efforts have been directed, for several years, to the synthesis of original chelating agents likely to form stable complexes in vivo with the numerous potential candidates for such applications. The stability of a non-macrocyclic ligand can be favourably influenced by the preorganization of the open chain. In fact, a semi-rigid structure such as that of trans-1,2-diaminocyclohexane limits the rotation of the ethylene bridge, so that the purpose of the cyclohexane design is to preorient the four pendent arms in a skew position. Therefore, we have developed a new simple and efficient synthesis pathway from trans-1,2-diaminocyclohexane to provide access to a new class of semi-rigid chelating agents. This same reactional scheme will be apply to our reactional intermediary, (1R * , 2R * , 4S * )-4-acetamido-1,2-diaminocyclohexane dihydrochloride, which will allow the synthesis of these same chelating agents, though functionalised back of the cycle by a termination allowed coupling to an antibody or any other biological substance such as a hapten. (orig.)

  5. Molecular Structure of WlbB, a Bacterial N-Acetyltransferase Involved in the Biosynthesis of 2,3-Diacetamido-2,3-dideoxy-d-mannuronic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Thoden, James B.; Holden, Hazel M. (UW)

    2010-09-08

    The pathogenic bacteria Pseudomonas aeruginosa and Bordetella pertussis contain in their outer membranes the rare sugar 2,3-diacetamido-2,3-dideoxy-D-mannuronic acid. Five enzymes are required for the biosynthesis of this sugar starting from UDP-N-acetylglucosamine. One of these, referred to as WlbB, is an N-acetyltransferase that converts UDP-2-acetamido-3-amino-2,3-dideoxy-D-glucuronic acid (UDP-GlcNAc3NA) to UDP-2,3-diacetamido-2,3-dideoxy-D-glucuronic acid (UDP-GlcNAc3NAcA). Here we report the three-dimensional structure of WlbB from Bordetella petrii. For this analysis, two ternary structures were determined to 1.43 {angstrom} resolution: one in which the protein was complexed with acetyl-CoA and UDP and the second in which the protein contained bound CoA and UDP-GlcNAc3NA. WlbB adopts a trimeric quaternary structure and belongs to the L{beta}H superfamily of N-acyltransferases. Each subunit contains 27 {beta}-strands, 23 of which form the canonical left-handed {beta}-helix. There are only two hydrogen bonds that occur between the protein and the GlcNAc3NA moiety, one between O{sup {delta}1} of Asn 84 and the sugar C-3{prime} amino group and the second between the backbone amide group of Arg 94 and the sugar C-5{prime} carboxylate. The sugar C-3{prime} amino group is ideally positioned in the active site to attack the si face of acetyl-CoA. Given that there are no protein side chains that can function as general bases within the GlcNAc3NA binding pocket, a reaction mechanism is proposed for WlbB whereby the sulfur of CoA ultimately functions as the proton acceptor required for catalysis.

  6. Structural and biochemical characterization of the β-N-acetylglucosaminidase from Thermotoga maritima: toward rationalization of mechanistic knowledge in the GH73 family.

    Science.gov (United States)

    Lipski, Alexandra; Hervé, Mireille; Lombard, Vincent; Nurizzo, Didier; Mengin-Lecreulx, Dominique; Bourne, Yves; Vincent, Florence

    2015-03-01

    Members of the GH73 glycosidase family cleave the β-1,4-glycosidic bond between the N-acetylglucosaminyl (GlcNAc) and N-acetylmuramyl (MurNAc) moieties in bacterial peptidoglycan. A catalytic mechanism has been proposed for members FlgJ, Auto, AcmA and Atl(WM) and the structural analysis of FlgJ and Auto revealed a conserved α/β fold reminiscent of the distantly related GH23 lysozyme. Comparison of the active site residues reveals variability in the nature of the catalytic general base suggesting two distinct catalytic mechanisms: an inverting mechanism involving two distant glutamate residues and a substrate-assisted mechanism involving anchimeric assistance by the C2-acetamido group of the GlcNAc moiety. Herein, we present the biochemical characterization and crystal structure of TM0633 from the hyperthermophilic bacterium Thermotoga maritima. TM0633 adopts the α/β fold of the family and displays β-N-acetylglucosaminidase activity on intact peptidoglycan sacculi. Site-directed mutagenesis identifies Glu34, Glu65 and Tyr118 as important residues for catalysis. A thorough bioinformatic analysis of the GH73 sequences identified five phylogenetic clusters. TM0633, FlgJ and Auto belong to a group of three clusters that conserve two carboxylate residues involved in a classical inverting acid-base mechanism. Members of the other two clusters lack a conserved catalytic general base supporting a substrate-assisted mechanism. Molecular modeling of representative members from each cluster suggests that variability in length of the β-hairpin region above the active site confers ligand-binding specificity and modulates the catalytic mechanisms within the GH73 family. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. Preparation of Chitosan Nanocompositeswith a Macroporous Structure by Unidirectional Freezing and Subsequent Freeze-Drying

    Directory of Open Access Journals (Sweden)

    Inmaculada Aranaz

    2014-11-01

    Full Text Available Chitosan is the N-deacetylated derivative of chitin, a naturally abundant mucopolysaccharide that consists of 2-acetamido-2-deoxy-β-d-glucose through a β (1→4 linkage and is found in nature as the supporting material of crustaceans, insects, etc. Chitosan has been strongly recommended as a suitable functional material because of its excellent biocompatibility, biodegradability, non-toxicity, and adsorption properties. Boosting all these excellent properties to obtain unprecedented performances requires the core competences of materials chemists to design and develop novel processing strategies that ultimately allow tailoring the structure and/or the composition of the resulting chitosan-based materials. For instance, the preparation of macroporous materials is challenging in catalysis, biocatalysis and biomedicine, because the resulting materials will offer a desirable combination of high internal reactive surface area and straightforward molecular transport through broad “highways” leading to such a surface. Moreover, chitosan-based composites made of two or more distinct components will produce structural or functional properties not present in materials composed of one single component. Our group has been working lately on cryogenic processes based on the unidirectional freezing of water slurries and/or hydrogels, the subsequent freeze-drying of which produce macroporous materials with a well-patterned structure. We have applied this process to different gels and colloidal suspensions of inorganic, organic, and hybrid materials. In this review, we will describe the application of the process to chitosan solutions and gels typically containing a second component (e.g., metal and ceramic nanoparticles, or carbon nanotubes for the formation of chitosan nanocomposites with a macroporous structure. We will also discuss the role played by this tailored composition and structure in the ultimate performance of these materials.

  8. The KL24 gene cluster and a genomic island encoding a Wzy polymerase contribute genes needed for synthesis of the K24 capsular polysaccharide by the multiply antibiotic resistant Acinetobacter baumannii isolate RCH51.

    Science.gov (United States)

    Kenyon, Johanna J; Kasimova, Anastasiya A; Shneider, Mikhail M; Shashkov, Alexander S; Arbatsky, Nikolay P; Popova, Anastasiya V; Miroshnikov, Konstantin A; Hall, Ruth M; Knirel, Yuriy A

    2017-03-01

    The whole-genome sequence of the multiply antibiotic resistant Acinetobacter baumannii isolate RCH51 belonging to sequence type ST103 (Institut Pasteur scheme) revealed that the set of genes at the capsule locus, KL24, includes four genes predicted to direct the synthesis of 3-acetamido-3,6-dideoxy-d-galactose (d-Fuc3NAc), and this sugar was found in the capsular polysaccharide (CPS). One of these genes, fdtE, encodes a novel bifunctional protein with an N-terminal FdtA 3,4-ketoisomerase domain and a C-terminal acetyltransferase domain. KL24 lacks a gene encoding a Wzy polymerase to link the oligosaccharide K units to form the CPS found associated with isolate RCH51, and a wzy gene was found in a small genomic island (GI) near the cpn60 gene. This GI is in precisely the same location as another GI carrying wzy and atr genes recently found in several A. baumannii isolates, but it does not otherwise resemble it. The CPS isolated from RCH51, studied by sugar analysis and 1D and 2D 1H and 13C NMR spectroscopy, revealed that the K unit has a branched pentasaccharide structure made up of Gal, GalNAc and GlcNAc residues with d-Fuc3NAc as a side branch, and the K units are linked via a β-d-GlcpNAc-(1→3)-β-d-Galp linkage formed by the Wzy encoded by the GI. The functions of the glycosyltransferases encoded by KL24 were assigned to formation of specific bonds. A correspondence between the order of the genes in KL24 and other KL and the order of the linkages they form was noted, and this may be useful in future predictions of glycosyltransferase specificities.

  9. Structural and Biochemical Investigation of PglF from Campylobacter jejuni Reveals a New Mechanism for a Member of the Short Chain Dehydrogenase/Reductase Superfamily

    Energy Technology Data Exchange (ETDEWEB)

    Riegert, Alexander S. [Department; Thoden, James B. [Department; Schoenhofen, Ian C. [National; Watson, David C. [National; Young, N. Martin [National; Tipton, Peter A. [Department; Holden, Hazel M. [Department

    2017-11-03

    Within recent years it has become apparent that protein glycosylation is not limited to eukaryotes. Indeed, in Campylobacter jejuni, a Gram-negative bacterium, more than 60 of its proteins are known to be glycosylated. One of the sugars found in such glycosylated proteins is 2,4-diacetamido-2,4,6-trideoxy-α-d-glucopyranose, hereafter referred to as QuiNAc4NAc. The pathway for its biosynthesis, initiating with UDP-GlcNAc, requires three enzymes referred to as PglF, PglE, and PlgD. The focus of this investigation is on PglF, an NAD+-dependent sugar 4,6-dehydratase known to belong to the short chain dehydrogenase/reductase (SDR) superfamily. Specifically, PglF catalyzes the first step in the pathway, namely, the dehydration of UDP-GlcNAc to UDP-2-acetamido-2,6-dideoxy-α-d-xylo-hexos-4-ulose. Most members of the SDR superfamily contain a characteristic signature sequence of YXXXK where the conserved tyrosine functions as a catalytic acid or a base. Strikingly, in PglF, this residue is a methionine. Here we describe a detailed structural and functional investigation of PglF from C. jejuni. For this investigation five X-ray structures were determined to resolutions of 2.0 Å or better. In addition, kinetic analyses of the wild-type and site-directed variants were performed. On the basis of the data reported herein, a new catalytic mechanism for a SDR superfamily member is proposed that does not require the typically conserved tyrosine residue.

  10. Combined high pressure and thermal processing on inactivation of type A and proteolytic type B spores of Clostridium botulinum.

    Science.gov (United States)

    Reddy, N Rukma; Marshall, Kristin M; Morrissey, Travis R; Loeza, Viviana; Patazca, Eduardo; Skinner, Guy E; Krishnamurthy, Kathiravan; Larkin, John W

    2013-08-01

    The aim of this study was to determine the resistance of multiple strains of Clostridium botulinum type A and proteolytic type B spores exposed to combined high pressure and thermal processing and compare their resistance with Clostridium sporogenes PA3679 and Bacillus amyloliquefaciens TMW-2.479-Fad-82 spores. The resistance of spores suspended in N-(2acetamido)-2-aminoethanesulfonic acid (ACES) buffer (0.05 M, pH 7.0) was determined at a process temperature of 105°C, with high pressures of 600, 700, and 750 MPa by using a laboratory-scale pressure test system. No surviving spores of the proteolytic B strains were detected after processing at 105°C and 700 MPa for 6 min. A . 7-log reduction of B. amyloliquefaciens spores was observed when processed for 4 min at 105°C and 700 MPa. D-values at 105°C and 700 MPa for type A strains ranged from 0.57 to 2.28 min. C. sporogenes PA3679 had a D-value of 1.48 min at 105°C and 700 MPa. Spores of the six type A strains with high D-values along with C. sporogenes PA3679 and B. amyloliquefaciens were further evaluated for their pressure resistance at pressures 600 and 750 MPa at 105°C. As the process pressure increased from 600 to 750 MPa at 105°C, D-values of some C. botulinum strains and C. sporogenes PA3679 spores decreased (i.e., 69-A, 1.91 to 1.33 min and PA3679, 2.35 to 1.29 min). Some C. botulinum type A strains were more resistant than C. sporogenes PA3679 and B. amyloliquefaciens to combined high pressure and heat, based on D-values determined at 105°C. Pulsed-field gel electrophoresis (PFGE) was also performed to establish whether strains with a similar restriction banding pattern also exhibited similar D-values. However, no correlation between the genomic background of a strain and its resistance to high pressure processing was observed, based on PFGE analysis. Spores of proteolytic type B strains of C. botulinum were less resistant to combined high pressure and heat (700 MPa and 105°C) treatment when

  11. Control of cell volume in the J774 macrophage by microtubule disassembly and cyclic AMP

    Science.gov (United States)

    Melmed, RN; Karanian, PJ; Berlin, RD

    1981-01-01

    We have explored the possibilities that cell volume is regulated by the status of microtubule assembly and cyclic AMP metabolism and may be coordinated with shape change. Treatment of J774.2 mouse macrophages with colchicine caused rapid microtubule disassembly and was associated with a striking increase (from 15-20 to more than 90 percent) in the proportion of cells with a large protuberance at one pole. This provided a simple experimental system in which shape changes occurred in virtually an entire cell population in suspension. Parallel changes in cell volume could then be quantified by isotope dilution techniques. We found that the shape change caused by colchicine was accompanied by a decrease in cell volume of approximately 20 percent. Nocodozole, but not lumicolchicine, caused identical changes in both cell shape and cell volume. The volume loss was not due to cell lysis nor to inhibition of pinocytosis. The mechanism of volume loss was also examined. Colchicine induced a small but reproducible increase in activity of the ouabain-sensitive Na(+), K(+)-dependent ATPase. However, inhibition of this enzyme/transport system by ouabain did not change cell volume nor did it block the colchicines-induced decrease in volume. One the other hand, SITS (4’acetamido, 4-isothiocyano 2,2’ disulfonic acid stilbene), an inhibitor of anion transport, inhibited the effects of colchicines, thus suggesting a role for an anion transport system in cell volume regulation. Because colchicine is known to activate adenylate cyclase in several systems and because cell shape changes are often induced by hormones that elevate cyclic AMP, we also examined the effects of cyclic AMP on cell volume. Agents that act to increase syclic AMP (cholera toxin, which activates adenylate cyclase; IBMX, and inhibitor of phosphodiesterase; and dibutyryl cyclic AMP) all caused a volume decrease comparable to that of colchicine. To define the effective metabolic pathway, we studied two mutants of J

  12. Evidence that biosynthesis of the second and third sugars of the archaellin Tetrasaccharide in the archaeon Methanococcus maripaludis occurs by the same pathway used by Pseudomonas aeruginosa to make a di-N-acetylated sugar.

    Science.gov (United States)

    Siu, Sarah; Robotham, Anna; Logan, Susan M; Kelly, John F; Uchida, Kaoru; Aizawa, Shin-Ichi; Jarrell, Ken F

    2015-05-01

    Methanococcus maripaludis has two surface appendages, archaella and type IV pili, which are composed of glycoprotein subunits. Archaellins are modified with an N-linked tetrasaccharide with the structure Sug-1,4-β-ManNAc3NAmA6Thr-1,4-β-GlcNAc3NAcA-1,3-β-GalNAc, where Sug is (5S)-2-acetamido-2,4-dideoxy-5-O-methyl-α-L-erythro-hexos-5-ulo-1,5-pyranose. The pilin glycan has an additional hexose attached to GalNAc. In this study, genes located in two adjacent, divergently transcribed operons (mmp0350-mmp0354 and mmp0359-mmp0355) were targeted for study based on annotations suggesting their involvement in biosynthesis of N-glycan sugars. Mutants carrying deletions in mmp0350, mmp0351, mmp0352, or mmp0353 were nonarchaellated and synthesized archaellins modified with a 1-sugar glycan, as estimated from Western blots. Mass spectroscopy analysis of pili purified from the Δmmp0352 strain confirmed a glycan with only GalNAc, suggesting mmp0350 to mmp0353 were all involved in biosynthesis of the second sugar (GlcNAc3NAcA). The Δmmp0357 mutant was archaellated and had archaellins with a 2-sugar glycan, as confirmed by mass spectroscopy of purified archaella, indicating a role for MMP0357 in biosynthesis of the third sugar (ManNAc3NAmA6Thr). M. maripaludis mmp0350, mmp0351, mmp0352, mmp0353, and mmp0357 are proposed to be functionally equivalent to Pseudomonas aeruginosa wbpABEDI, involved in converting UDP-N-acetylglucosamine to UDP-2,3-diacetamido-2,3-dideoxy-d-mannuronic acid, an O5-specific antigen sugar. Cross-domain complementation of the final step of the P. aeruginosa pathway with mmp0357 supports this hypothesis. This work identifies a series of genes in adjacent operons that are shown to encode the enzymes that complete the entire pathway for generation of the second and third sugars of the N-linked tetrasaccharide that modifies archaellins of Methanococcus maripaludis. This posttranslational modification of archaellins is important, as it is necessary for

  13. Identification of genes involved in the biosynthesis of the third and fourth sugars of the Methanococcus maripaludis archaellin N-linked tetrasaccharide.

    Science.gov (United States)

    Ding, Yan; Jones, Gareth M; Uchida, Kaoru; Aizawa, Shin-Ichi; Robotham, Anna; Logan, Susan M; Kelly, John; Jarrell, Ken F

    2013-09-01

    N-glycosylation is a protein posttranslational modification found in all three domains of life. Many surface proteins in Archaea, including S-layer proteins, pilins, and archaellins (archaeal flagellins) are known to contain N-linked glycans. In Methanococcus maripaludis, the archaellins are modified at multiple sites with an N-linked tetrasaccharide with the structure Sug-1,4-β-ManNAc3NAmA6Thr-1,4-β-GlcNAc3NAcA-1,3-β-GalNAc, where Sug is the unique sugar (5S)-2-acetamido-2,4-dideoxy-5-O-methyl-α-l-erythro-hexos-5-ulo-1,5-pyranose. In this study, four genes--mmp1084, mmp1085, mmp1086, and mmp1087--were targeted to determine their potential involvement of the biosynthesis of the sugar components in the N-glycan, based on bioinformatics analysis and proximity to a number of genes which have been previously demonstrated to be involved in the N-glycosylation pathway. The genes mmp1084 to mmp1087 were shown to be cotranscribed, and in-frame deletions of each gene as well as a Δmmp1086Δmmp1087 double mutant were successfully generated. All mutants were archaellated and motile. Mass spectrometry examination of purified archaella revealed that in Δmmp1084 mutant cells, the threonine linked to the third sugar of the glycan was missing, indicating a putative threonine transferase function of MMP1084. Similar analysis of the archaella of the Δmmp1085 mutant cells demonstrated that the glycan lacked the methyl group at the C-5 position of the terminal sugar, indicating that MMP1085 is a methyltransferase involved in the biosynthesis of this unique sugar. Deletion of the remaining two genes, mmp1086 and mmp1087, either singularly or together, had no effect on the structure of the archaellin N-glycan. Because of their demonstrated involvement in the N-glycosylation pathway, we designated mmp1084 as aglU and mmp1085 as aglV.

  14. Investigation of the Mechanism of Electron Capture and Electron Transfer Dissociation of Peptides with a Covalently Attached Free Radical Hydrogen Atom Scavenger.

    Science.gov (United States)

    Sohn, Chang Ho; Yin, Sheng; Peng, Ivory; Loo, Joseph A; Beauchamp, J L

    2015-11-15

    The mechanisms of electron capture and electron transfer dissociation (ECD and ETD) are investigated by covalently attaching a free-radical hydrogen atom scavenger to a peptide. The 2,2,6,6-tetramethylpiperidin-l-oxyl (TEMPO) radical was chosen as the scavenger due to its high hydrogen atom affinity (ca. 280 kJ/mol) and low electron affinity (ca. 0.45 ev), and was derivatized to the model peptide, FQX TEMPO EEQQQTEDELQDK. The X TEMPO residue represents a cysteinyl residue derivatized with an acetamido-TEMPO group. The acetamide group without TEMPO was also examined as a control. The gas phase proton affinity (882 kJ/mol) of TEMPO is similar to backbone amide carbonyls (889 kJ/mol), minimizing perturbation to internal solvation and sites of protonation of the derivatized peptides. Collision induced dissociation (CID) of the TEMPO tagged peptide dication generated stable odd-electron b and y type ions without indication of any TEMPO radical induced fragmentation initiated by hydrogen abstraction. The type and abundance of fragment ions observed in the CID spectra of the TEMPO and acetamide tagged peptides are very similar. However, ECD of the TEMPO labeled peptide dication yielded no backbone cleavage. We propose that a labile hydrogen atom in the charge reduced radical ions is scavenged by the TEMPO radical moiety, resulting in inhibition of N-C α backbone cleavage processes. Supplemental activation after electron attachment (ETcaD) and CID of the charge-reduced precursor ion generated by electron transfer of the TEMPO tagged peptide dication produced a series of b + H (b H ) and y + H (y H ) ions along with some c ions having suppressed intensities, consistent with stable O-H bond formation at the TEMPO group. In summary, the results indicate that ECD and ETD backbone cleavage processes are inhibited by scavenging of a labile hydrogen atom by the localized TEMPO radical moiety. This observation supports the conjecture that ECD and ETD processes involve long

  15. The Biosynthesis of UDP-d-FucNAc-4N-(2)-oxoglutarate (UDP-Yelosamine) in Bacillus cereus ATCC 14579

    Science.gov (United States)

    Hwang, Soyoun; Li, Zi; Bar-Peled, Yael; Aronov, Avi; Ericson, Jaime; Bar-Peled, Maor

    2014-01-01

    Surface glycan switching is often observed when micro-organisms transition between different biotic and abiotic niches, including biofilms, although the advantages of this switching to the organism are not well understood. Bacillus cereus grown in a biofilm-inducing medium has been shown to synthesize an unusual cell wall polysaccharide composed of the repeating subunit →6)Gal(α1–2)(2-R-hydroxyglutar-5-ylamido)Fuc2NAc4N(α1–6)GlcNAc(β1→, where galactose is linked to the hydroxyglutarate moiety of FucNAc-4-amido-(2)-hydroxyglutarate. The molecular mechanism involved in attaching 2-hydroxyglutarate to 4-amino-FucNAc has not been determined. Here, we show two genes in B. cereus ATCC 14579 encoding enzymes involved in the synthesis of UDP-FucNAc-4-amido-(2)-oxoglutarate (UDP-Yelosamine), a modified UDP-sugar not previously reported to exist. Using mass spectrometry and real time NMR spectroscopy, we show that Bc5273 encodes a C4″-aminotransferase (herein referred to as Pat) that, in the presence of pyridoxal phosphate, transfers the primary amino group of l-Glu to C-4″ of UDP-4-keto-6-deoxy-d-GlcNAc to form UDP-4-amino-FucNAc and 2-oxoglutarate. Pat also converts 4-keto-xylose, 4-keto-glucose, and 4-keto-2-acetamido-altrose to their corresponding UDP-4-amino-sugars. Bc5272 encodes a carboxylate-amine ligase (herein referred as Pyl) that, in the presence of ATP and Mg(II), adds 2-oxoglutarate to the 4-amino moiety of UDP-4-amino-FucNAc to form UDP-Yelosamine and ADP. Pyl is also able to ligate 2-oxoglutarate to other 4-amino-sugar derivatives to form UDP-Yelose, UDP-Solosamine, and UDP-Aravonose. Characterizing the metabolic pathways involved in the formation of modified nucleotide sugars provides a basis for understanding some of the mechanisms used by bacteria to modify or alter their cell surface polysaccharides in response to changing growth and environmental challenges. PMID:25368324

  16. The biosynthesis of UDP-d-FucNAc-4N-(2)-oxoglutarate (UDP-Yelosamine) in Bacillus cereus ATCC 14579: Pat and Pyl, an aminotransferase and an ATP-dependent Grasp protein that ligates 2-oxoglutarate to UDP-4-amino-sugars.

    Science.gov (United States)

    Hwang, Soyoun; Li, Zi; Bar-Peled, Yael; Aronov, Avi; Ericson, Jaime; Bar-Peled, Maor

    2014-12-19

    Surface glycan switching is often observed when micro-organisms transition between different biotic and abiotic niches, including biofilms, although the advantages of this switching to the organism are not well understood. Bacillus cereus grown in a biofilm-inducing medium has been shown to synthesize an unusual cell wall polysaccharide composed of the repeating subunit →6)Gal(α1-2)(2-R-hydroxyglutar-5-ylamido)Fuc2NAc4N(α1-6)GlcNAc(β1→, where galactose is linked to the hydroxyglutarate moiety of FucNAc-4-amido-(2)-hydroxyglutarate. The molecular mechanism involved in attaching 2-hydroxyglutarate to 4-amino-FucNAc has not been determined. Here, we show two genes in B. cereus ATCC 14579 encoding enzymes involved in the synthesis of UDP-FucNAc-4-amido-(2)-oxoglutarate (UDP-Yelosamine), a modified UDP-sugar not previously reported to exist. Using mass spectrometry and real time NMR spectroscopy, we show that Bc5273 encodes a C4″-aminotransferase (herein referred to as Pat) that, in the presence of pyridoxal phosphate, transfers the primary amino group of l-Glu to C-4″ of UDP-4-keto-6-deoxy-d-GlcNAc to form UDP-4-amino-FucNAc and 2-oxoglutarate. Pat also converts 4-keto-xylose, 4-keto-glucose, and 4-keto-2-acetamido-altrose to their corresponding UDP-4-amino-sugars. Bc5272 encodes a carboxylate-amine ligase (herein referred as Pyl) that, in the presence of ATP and Mg(II), adds 2-oxoglutarate to the 4-amino moiety of UDP-4-amino-FucNAc to form UDP-Yelosamine and ADP. Pyl is also able to ligate 2-oxoglutarate to other 4-amino-sugar derivatives to form UDP-Yelose, UDP-Solosamine, and UDP-Aravonose. Characterizing the metabolic pathways involved in the formation of modified nucleotide sugars provides a basis for understanding some of the mechanisms used by bacteria to modify or alter their cell surface polysaccharides in response to changing growth and environmental challenges. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. The spectroscopic impact of interactions with the four Gouterman orbitals from peripheral decoration of porphyrins with simple electron withdrawing and donating groups.

    Science.gov (United States)

    Zhang, Angel; Kwan, Lydia; Stillman, Martin J

    2017-11-07

    Tetrapyrroles are of great interest for solar cell and photodynamic therapy applications due to their structural analogy with chlorophyll, a natural photosensitizer. Unsubstituted symmetric porphyrins exhibit weak absorption in the red region which makes them unsuitable for these applications. The push-pull peripheral decoration modifies the energies of the frontier molecular orbitals, which in turn influences the tetrapyrrole's spectroscopic properties. The absorption, magnetic circular dichroism, and emission spectra were measured for four zinc tetratolylporphyrin compounds substituted peripherally with a fused dimethoxybenzo group as an electron withdrawing group (EWG) on one pyrrole and on the opposite pyrrole, a single acetamido (1), a nitro (2), a proton (3), or a benzoylamino (4) substituent. Unusually, the magnetic circular dichroism spectrum of 2 exhibited a negative A term for the lowest energy absorption band (the Q band) and its emission spectrum was also unlike those of 1, 3, and 4. A complete computational analysis was carried out to obtain the energies and electron distribution, shown by electron density surfaces, of the four Gouterman MOs. TD-DFT calculations showed that for 2, ΔLUMO was greater than ΔHOMO, which accounted for the observed negative A term. The trend in the estimated MCD A term magnitudes, normalized to the absorbance as [A/(dipole strength) BM], provides experimental confirmation of the computationally determined ratio of ΔLUMO/ΔHOMO data. The value of ΔHOMO was confirmed by the trend in oscillator strengths. A series of fictive porphyrins (F1-F5) incorporating simple push-pull substituents were designed and their electronic structures were investigated using TD-DFT calculations. The substituents in the five fictive molecules illustrate the differential effect of the donor and acceptor groups in the β-position of the pyrroles on the relative stabilities of the four Gouterman orbitals. NO 2 groups result in the greatest

  18. Structure and Active Stie Residues of Pg1D, an N-Acetyltransferase from the Bacillosamine Synthetic Pathway Required for N-Glycan Synthesis in Campylobacter jejuni

    Energy Technology Data Exchange (ETDEWEB)

    Rangarajan,E.; Ruane, K.; Sulea, T.; Watson, D.; Proteau, A.; Leclerc, S.; Cygler, M.; Matte, A.; Young, N.

    2008-01-01

    Campylobacter jejuni is highly unusual among bacteria in forming N-linked glycoproteins. The heptasaccharide produced by its pgl system is attached to protein Asn through its terminal 2, 4-diacetamido-2, 4,6-trideoxy-d-Glc (QuiNAc4NAc or N, N'-diacetylbacillosamine) moiety. The crucial, last part of this sugar's synthesis is the acetylation of UDP-2-acetamido-4-amino-2, 4,6-trideoxy-d-Glc by the enzyme PglD, with acetyl-CoA as a cosubstrate. We have determined the crystal structures of PglD in CoA-bound and unbound forms, refined to 1.8 and 1.75 Angstroms resolution, respectively. PglD is a trimer of subunits each comprised of two domains, an N-terminal {alpha}/{beta}-domain and a C-terminal left-handed {beta}-helix. Few structural differences accompany CoA binding, except in the C-terminal region following the {beta}-helix (residues 189-195), which adopts an extended structure in the unbound form and folds to extend the {beta}-helix upon binding CoA. Computational molecular docking suggests a different mode of nucleotide-sugar binding with respect to the acetyl-CoA donor, with the molecules arranged in an 'L-shape', compared with the 'in-line' orientation in related enzymes. Modeling indicates that the oxyanion intermediate would be stabilized by the NH group of Gly143', with His125' the most likely residue to function as a general base, removing H+ from the amino group prior to nucleophilic attack at the carbonyl carbon of acetyl-CoA. Site-specific mutations of active site residues confirmed the importance of His125', Glu124', and Asn118. We conclude that Asn118 exerts its function by stabilizing the intricate hydrogen bonding network within the active site and that Glu124' may function to increase the pKa of the putative general base, His125'.

  19. Tempol protects cardiomyocytes from nucleoside reverse transcriptase inhibitor-induced mitochondrial toxicity.

    Science.gov (United States)

    Liu, Yongmin; Shim, Eunwoo; Nguyen, Phuonggiang; Gibbons, Alexander T; Mitchell, James B; Poirier, Miriam C

    2014-05-01

    Nucleoside reverse transcriptase inhibitors (NRTIs), essential components of combinational therapies used for treatment of human immunodeficiency virus-1, damage heart mitochondria. Here, we have shown mitochondrial compromise in H9c2 rat cardiomyocytes exposed for 16 passages (P) to the NRTIs zidovudine (AZT, 50μM) and didanosine (ddI, 50μM), and we have demonstrated protection from mitochondrial compromise in cells treated with 200μM 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine (Tempol) or 200μM 1-hydroxy-4-[2-triphenylphosphonio)-acetamido]-2,2,6,6-tetramethylpiperidine (Tempol-H), along with AZT/ddI, for 16P. Exposure to AZT/ddI caused a moderate growth inhibition at P3, P5, P7, and P13, which was not altered by addition of Tempol or Tempol-H. Mitochondrial oxidative phosphorylation capacity was determined as uncoupled oxygen consumption rate (OCR) by Seahorse XF24 Analyzer. At P5, P7, and P13, AZT/ddI-exposed cells showed an OCR reduction of 8.8-57.2% in AZT/ddI-exposed cells, compared with unexposed cells. Addition of Tempol or Tempol-H, along with AZT/ddI, resulted in OCR levels increased by about 300% above the values seen with AZT/ddI alone. The Seahorse data were further supported by electron microscopy (EM) studies in which P16 cells exposed to AZT/ddI/Tempol had less mitochondrial pathology than P16 cells exposed to AZT/ddI. Western blots of P5 cells showed that Tempol and Tempol-H upregulated expression of mitochondrial uncoupling protein-2 (UCP-2). However, Complex I activity that was reduced by AZT/ddI, was not restored in the presence of AZT/ddI/Tempol. Superoxide levels were increased in the presence of AZT/ddI and significantly decreased in cells exposed to AZT/3TC/Tempol at P3, P7, and P10. In conclusion, Tempol protects against NRTI-induced mitochondrial compromise, and UCP-2 plays a role through mild uncoupling.

  20. O-GlcNAc modification of NFκB p65 inhibits TNF-α-induced inflammatory mediator expression in rat aortic smooth muscle cells.

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    Dongqi Xing

    Full Text Available BACKGROUND: We have shown that glucosamine (GlcN or O-(2-acetamido-2-deoxy-D-glucopyranosylideneamino-N-phenylcarbamate (PUGNAc treatment augments O-linked-N-acetylglucosamine (O-GlcNAc protein modification and attenuates inflammatory mediator expression, leukocyte infiltration and neointima formation in balloon injured rat carotid arteries and have identified the arterial smooth muscle cell (SMC as the target cell in the injury response. NFκB signaling has been shown to mediate the expression of inflammatory genes and neointima formation in injured arteries. Phosphorylation of the p65 subunit of NFκB is required for the transcriptional activation of NFκB. This study tested the hypothesis that GlcN or PUGNAc treatment protects vascular SMCs against tumor necrosis factor (TNF-α induced inflammatory stress by enhancing O-GlcNAcylation and inhibiting TNF-α induced phosphorylation of NFκB p65, thus inhibiting NFκB signaling. METHODOLOGY/PRINCIPAL FINDINGS: Quiescent rat aortic SMCs were pretreated with GlcN (5 mM, PUGNAc (10(-4 M or vehicle and then stimulated with TNF-α (10 ng/ml. Both treatments inhibited TNF-α-induced expression of chemokines [cytokine-induced neutrophil chemoattractant (CINC-2β and monocyte chemotactic protein (MCP-1] and adhesion molecules [vascular cell adhesion molecule (VCAM-1 and P-Selectin]. Both treatments inhibited TNF-α induced NFκB p65 activation and promoter activity, increased NFκB p65 O-GlcNAcylation and inhibited NFκB p65 phosphorylation at Serine 536, thus promoting IκBα binding to NFκB p65. CONCLUSIONS: There is a reciprocal relationship between O-GlcNAcylation and phosphorylation of NFκB p65, such that increased NFκB p65 O-GlcNAc modification inhibits TNF-α-Induced expression of inflammatory mediators through inhibition of NFκB p65 signaling. These findings provide a mechanistic basis for our previous observations that GlcN and PUGNAc treatments inhibit inflammation and remodeling induced by

  1. The structure and significance of enterobacterial common antigen (ECA

    Directory of Open Access Journals (Sweden)

    Tomasz Kasper Goździewicz

    2015-09-01

    Full Text Available The enterobacterial common antigen (ECA is a carbohydrate-derived cell surface antigen present in all Gram-negative bacteria belonging to Enterobacteriaceae family. Biosynthetic pathways shared by ECA and LPS (endotoxin suggest close connections between these antigens. ECA occurs in three different forms: a phosphatidyl-linked linear polysaccharide anchored on the cell surface (ECAPG, a cyclic form built of 4-6 repeating units localized in the periplasm (ECACYC and as a linear polysaccharide covalently linked to LPS core oligosaccharide (ECALPS. Regardless of ECA form, poly- and oligosaccharides of ECA consist of the biological trisaccharide repeating units: →3-α-d-Fucp4NAc-(1→4-β-d-ManpNAcA-(1→4-α-d-GlcpNAc-(1→, where Fucp4NAc refers to 4-acetamido-2,4-dideoxygalactose, ManpNAcA to N-acetyl-mannosaminuronic acid and GlcpNAc to N-acetylglucosamine. ECAPG and ECALPS consisting of one unit with Fucp4NAc as a terminal sugar were also identified. The number of the studies shows its occurrence in all members of enteric bacteria with a few exceptions such as Erwinia chrysanthemi. The presence of ECA was also shown for such genera as Plesiomonas [4] and Yersinia [36], previously belonging to the Vibrionaceae and Pasteurellaceae families, respectively. It was one of the reasons to include these two taxa in the Enterobacteriaceae family. The function of ECA is not fully understood, but it was reported that its occurrence is important in resistance of bacterial cells to environmental conditions, such as bile salts in the human digestive tract. The immunogenicity of ECA seems very interesting in the fact that only sparse rough Gram-negative strains, such as Shigella sonnei phase II, Escherichia coli R1, R2, R4, K-12, and Yersinia enterocolitica O:3 are able to induce the production of specific anti-ECA antibodies. It is the effect of the ECALPS, and the evidence for the existence of such covalent linkage was provided by structural analysis of S

  2. Metal and Ligand Effects on the Construction of Divalent Coordination Polymers Based on bis-Pyridyl-bis-amide and Polycarboxylate Ligands

    Directory of Open Access Journals (Sweden)

    Miao-Ning Chang

    2017-12-01

    Full Text Available Ten coordination polymers constructed from divalent metal salts, polycarboxylic acids, and bis-pyridyl-bis-amide ligands with different donor atom positions and flexibility are reported. They were structurally characterized by single-crystal X-ray diffraction. The ten coordination polymers are as follows: (1 {[Ni(L1(3,5-PDA(H2O3]·2H2O}n (L1 = N,N′-di(3-pyridylsuberoamide, 3,5-H2PDA = 3,5-pyridinedicarboxylic acid; (2 {[Ni2(L12(1,3,5-HBTC2(H2O4]·H2O}n (1,3,5-H3BTC = 1,3,5-benzenetricarboxylic acid; (3 {[Ni(L2(5-tert-IPA(H2O2]·2H2O}n (L2 = N,N′-di(3-pyridyladipoamide, 5-tert-H2IPA = 5-tert-butylisophthalic acid; (4 [Ni(L31.5(5-tert-IPA]n (L3 = N,N′-di(4-pyridyladipoamide; (5 [Co(L1(1,3,5-HBTC(H2O]n; (6 {[Co3(L13(1,3,5-BTC2(H2O2]·6H2O}n; (7 [Cu(L4(AIPA]n (L4 = N,N′-bis(3-pyridinylterephthalamide, H2AIPA = 5-acetamido isophthalic acid; (8 {[Cu(L20.5(AIPA]·MeOH}n; (9 {[Zn(L4(AIPA]·2H2O}n; and (10 {[Zn(L2(AIPA]·2H2O}n. Complex 1 forms a 1D chain and 2 is a two-fold interpenetrated 2D layer with the sql topology, while 3 is a 2D layer with the hcp topology and 4 shows a self-catenated 3D framework with the rare (42·67·8-hxg-d-5-C2/c topology. Different Co/1,3,5-H3BTC ratios were used to prepare 5 and 6, affording a 2D layer with the sql topology and a 2D layer with the (4·852(42(832(8 topology that can be further simplified to an hcp topology. While complex 7 is a 2D layer with the (42·67·8(42·6-3,5L2 topology and 8 is a 2-fold interpenetrated 3D framework with the pcu topology, complexes 9 and 10 are self-catenated 3D frameworks with the (424·64-8T2 and the (44·610·8-mab topologies, respectively. The effects of the identity of the metal center, the ligand isomerism, and the flexibility of the spacer ligands on the structural diversity of these divalent coordination polymers are discussed. The luminescent properties of 9 and 10 and their photocatalytic effects on the degradation of dyes are also investigated.

  3. Thermal and Pressure-Assisted Thermal Destruction Kinetics for Spores of Type A Clostridium botulinum and Clostridium sporogenes PA3679.

    Science.gov (United States)

    Reddy, N Rukma; Patazca, Eduardo; Morrissey, Travis R; Skinner, Guy E; Loeza, Viviana; Schill, Kristin M; Larkin, John W

    2016-02-01

    The purpose of this study was to determine the inactivation kinetics of the spores of the most resistant proteolytic Clostridium botulinum strains (Giorgio-A and 69-A, as determined from an earlier screening study) and of Clostridium sporogenes PA3679 and to compare the thermal and pressure-assisted thermal resistance of these spores. Spores of these strains were prepared using a biphasic medium method. C. sporogenes PA3679 spores were heat treated before spore preparation. Using laboratory-scale and pilot-scale pressure test systems, spores of Giorgio-A, 69-A, and PA3679 suspended in ACES [N-(2-acetamido)-2-aminoethanesulfonic acid] buffer (pH 7.0) were exposed to various combinations of temperature (93 to 121°C) and pressure (0.1 to 750 MPa) to determine their resistance. More than a 5-log reduction occurred after 3 min at 113°C for spores of Giorgio-A and 69-A and after 5 min at 117°C for spores of PA3679. A combination of high temperatures (93 to 121°C) and pressures yielded greater log reductions of spores of Giorgio-A, 69-A, and PA3679 compared with reduction obtained with high temperatures alone. No survivors from initial levels (>5.0 log CFU) of Giorgio-A and 69-A were detected when processed at a combination of high temperature (117 and 121°C) and high pressure (600 and 750 MPa) for 4.5-log reduction of PA3679 spores. Thermal D-values of Giorgio-A, 69-A, and PA3679 spores decreased (i.e., 29.1 to 0.33 min for Giorgio-A, 40.5 to 0.27 min for 69-A, and 335.2 to 2.16 min for PA3679) as the temperature increased from 97 to 117°C. Pressure-assisted thermal D-values of Giorgio-A, 69-A, and PA3679 also decreased as temperature increased from 97 to 121°C at both pressures (600 and 750 MPa) (i.e., 17.19 to 0.15 min for Giorgio-A, 9.58 to 0.15 min for 69-A, and 12.93 to 0.33 min for PA3679 at 600 MPa). At higher temperatures (117 or 121°C), increasing pressure from 600 to 750 MPa had an effect on pressure-assisted thermal D-values of PA3679 (i.e., at 117

  4. Depolymerization and de-N-acetylation of chitin oligomers in hydrochloric acid.

    Science.gov (United States)

    Einbu, Aslak; Vårum, Kjell M

    2007-01-01

    The monosaccharide 2-amino-2-deoxy-D-glucose (glucosamine, GlcN) has recently drawn much attention in relation to its use to treat or prevent osteoarthritis in humans. Glucosamine is prepared from chitin, a process that is performed in concentrated acid, such as hydrochloric acid. This process involves two acid-catalyzed processes, that is, the hydrolysis of the glycosidic linkages (depolymerization) and of the N-acetyl linkages (de-N-acetylation). The depolymerization reaction has previously been found to be much faster compared to the deacetylation, with the consequence that the chitin chain will first be hydrolyzed to the monomer 2-acetamido-2-deoxy-D-glucose (N-acetylglucosamine, GlcNAc) which is subsequently deacetylated. We have found that the chitin disaccharide GlcNAc(1-->4)GlcNAc could be completely hydrolyzed to the monosaccharide GlcNAc with negligible concomitant de-N-acetylation, and the chitin disaccharide and monosaccharide were further used to study the depolymerization reaction and the de-N-acetylation reaction, respectively. The reactions were performed in hydrochloric acid as a function of acid concentration (3-12 M) and temperature (20-35 degrees C), and 1H-NMR spectroscopy was used to monitor the reaction rates. The 1H NMR spectrum of GlcNAc in concentrated (12 M) and deuterated hydrochloric acid at 25 degrees C was assigned. The glucofuranosyl oxazolinium (3) ion was found to exist in equilibrium with the alpha- and beta-anomers of the pyranose form of GlcNAc, where 3 was present in half the total molar concentrations of the two anomeric forms of GlcNAc. At lower acid concentration (3-6 M), only trace concentrations of 3 could be detected. The rate of de-N-acetylation of GlcNAc was determined as a function of hydrochloric acid concentration, showing a maximum at 6 M and decreasing by a factor of 2 upon decreasing or increasing the acid concentration to 3 or 12 M. The activation energy for hydrolysis of the N-acetyl linkage of GlcNAc was

  5. Biodistribution and radiation dosimetry of 18F-CP-18, a potential apoptosis imaging agent, as determined from PET/CT scans in healthy volunteers.

    Science.gov (United States)

    Doss, Mohan; Kolb, Hartmuth C; Walsh, Joseph C; Mocharla, Vani; Fan, Hong; Chaudhary, Ashok; Zhu, Zhihong; Alpaugh, R Katherine; Lango, Miriam N; Yu, Jian Q

    2013-12-01

    (18)F-CP-18, or (18S,21S,24S,27S,30S)-27-(2-carboxyethyl)-21-(carboxymethyl)-30-((2S,3R,4R,5R,6S)-6-((2-(4-(3-F18-fluoropropyl)-1H-1,2,3-triazol-1-yl)acetamido)methyl)-3,4,5-trihydroxytetrahydro-2H-pyran-2-carboxamido)-24-isopropyl-18-methyl-17,20,23,26,29-pentaoxo-4,7,10,13-tetraoxa-16,19,22,25,28-pentaazadotriacontane-1,32-dioic acid, is being evaluated as a tissue apoptosis marker for PET imaging. The purpose of this study was to determine the biodistribution and estimate the normal-organ radiation-absorbed doses and effective dose from (18)F-CP-18. Successive whole-body PET/CT scans were obtained at approximately 7, 45, 90, 130, and 170 min after intravenous injection of (18)F-CP-18 in 7 healthy human volunteers. Blood samples and urine were collected between the PET/CT scans, and the biostability of (18)F-CP-18 was assessed using high-performance liquid chromatography. The PET scans were analyzed to determine the radiotracer uptake in different organs. OLINDA/EXM software was used to calculate human radiation doses based on the biodistribution of the tracer. (18)F-CP-18 was 54% intact in human blood at 135 min after injection. The tracer cleared rapidly from the blood pool with a half-life of approximately 30 min. Relatively high (18)F-CP-18 uptake was observed in the kidneys and bladder, with diffuse uptake in the liver and heart. The mean standardized uptake values (SUVs) in the bladder, kidneys, heart, and liver at around 50 min after injection were approximately 65, 6, 1.5, and 1.5, respectively. The calculated effective dose was 38 ± 4 μSv/MBq, with the urinary bladder wall having the highest absorbed dose at 536 ± 61 μGy/MBq using a 4.8-h bladder-voiding interval for the male phantom. For a 1-h voiding interval, these doses were reduced to 15 ± 2 μSv/MBq and 142 ± 15 μGy/MBq, respectively. For a typical injected activity of 555 MBq, the effective dose would be 21.1 ± 2.2 mSv for the 4.8-h interval, reduced to 8.3 ± 1.1 mSv for the 1-h interval

  6. The structures of six urinary oligosaccharides that are characteristic for a patient with Morquio syndrome type B.

    Science.gov (United States)

    Michalski, J C; Strecker, G; van Halbeek, H; Dorland, L; Vliegenthart, J F

    1982-03-01

    Morquio syndrome type B is an inherited, lysosomal storage disease characterised by a marked deficiency in acid beta-D-galactosidase, while the 2-acetamido-2-deoxy-beta-D-galactose 6-sulphate sulphatase activity is normal. Urinary oligosaccharides were studied in order to evaluate the effect of the diminished beta-D-galactosidase activity on the catabolism of glycoconjugates and to compare their structure with those excreted by patients with GM1-gangliosidosis. The following oligosaccharides were isolated: beta-D-Galp-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 2)-alpha-D-Manp-(1 leads to 6)-beta-D-Manp-(1 leads to 4)-D-GlcpNac(1), beta-D-Galp-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 2)-alpha-D-Manp-(1 leads to 6)-[alpha-D-Manp-(1 leads to 3)]-beta-D-Manp-(1 leads to 4)-D-GlcpNAc (2a), beta-D-Galp-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 2)-alpha-D-Manp-(1 leads to 3)-[alpha-D-Manp-(1 leads to 6)]-beta-D-Manp-(1 leads to 4)-D-GlcpNAc (2b), beta-D-Galp-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 2)-alpha-D-Manp-(1 leads to 3)-[beta-D-Galp-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 2)-alpha-D-Manp-(1 leads to 6)]-beta-D-Manp-(1 leads to 4)-D-GlcpNAc (3), beta-D-Galp-(1 leads to 4)-beta-D-Glcp-NAc-(1 leads to 2)-alpha-D-Manp-(1 leads to 3)-(beta-D-Galp-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 2)-[beta-D-Galp-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 6)]-alpha-D-Manp-(1 leads to 6))-beta-D-Manp-(1 leads to 4)-D-GlcpNAc (4), beta-D-Galp-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 2)-alpha-D-Manp-(1 leads to 3)-[beta-D-GlcpNAc-(1 leads to 4)]-[beta-D-Glap-(1 leads to 4)-beta-D-GlcpNAc-(1 leads to 2)-alpha-D-Manp-(1 leads to 6)]-beta-D-Manp-(1 leads to 4)-D-Glcp-NAc (5). Significant differences between Morquio syndrome type B and GM1- gangliosidosis have been observed, with regard to the excretion rate and the specific structures of urinary oligosaccharides. Compounds 2a, 2b, and 5 are novel members of the series of oligosaccharides isolated from the urine of patients with

  7. Side chain modified 5-deazafolate and 5-deazatetrahydrofolate analogues as mammalian folylpolyglutamate synthetase and glycinamide ribonucleotide formyltransferase inhibitors: synthesis and in vitro biological evaluation.

    Science.gov (United States)

    Rosowsky, A; Forsch, R A; Reich, V E; Freisheim, J H; Moran, R G

    1992-05-01

    5-Deazafolate and 5-deazatetrahydrofolate (DATHF) analogues with the glutamic acid side chain replaced by homocysteic acid (HCysA), 2-amino-4-phosphonobutanoic acid (APBA), and ornithine (Orn) were synthesized as part of a larger program directed toward inhibitors of folylpolyglutamate synthetase (FPGS) as probes of the FPGS active site and as potential therapeutic agents. The tetrahydro compounds were also of interest as non-polyglutamatable inhibitors of the purine biosynthetic enzyme glycinamide ribonucleotide formyltransferase (GARFT). Reductive coupling of N2-acetamido-6-formylpyrido[2,3-d]pyrimidin-4(3H)-one with 4-aminobenzoic acid, followed by N10-formylation, mixed anhydride condensation of the resultant N2-acetyl-N10-formyl-5- deazapteroic acid with L-homocysteic acid, and removal of the N2-acetyl and N10-formyl groups with NaOH, afforded N-(5-deazapteroyl)-L-homocysteic acid (5-dPteHCysA). Mixed anhydride condensation of N2-acetyl-N10-formyl- 5-deazapteroic acid with methyl D,L-2-amino-4-(diethoxyphosphinyl)butanoic acid, followed by consecutive treatment with Me3SiBr and NaOH, yielded D,L-2-[(5-deazapteroyl)amino]-4-phosphonobutanoic acid (5-dPteAPBA). Treatment with NaOH alone led to retention of one ethyl ester group on the phosphonate moiety. Catalytic hydrogenation of N2-acetyl-N10-formyl-5-deazapteroic acid followed by mixed anhydride condensation with methyl L-homocysteate and deprotection with NaOH afforded N-(5,6,7,8-tetrahydro-5-deazapteroyl)-L-homocysteic acid (5-dH4PteHCysA). Similar chemistry starting from methyl D,L-2-amino-4-(diethoxyphosphinyl)butanoic acid and methyl N delta-(benzyloxycarbonyl)-L-ornithinate yielded D,L-2-[(5-deaza-5,6,7,8-tetrahydropteroyl)amino]-4-phosphonobut ano ic acid (5-dH4Pte-APBA) and N alpha-(5-deaza-5,6,7,8-tetrahydropteroyl)-L-ornithine (5-dH4PteOrn), respectively. The 5-deazafolate analogues were inhibitors of mouse liver FPGS, and the DATHF analogues inhibited both mouse FPGS and mouse leukemic cell GARFT

  8. Pharmacological characterization of the bradykinin B2 receptor: inter-species variability and dissociation between binding and functional responses.

    Science.gov (United States)

    Paquet, J L; Luccarini, J M; Fouchet, C; Defrêne, E; Loillier, B; Robert, C; Bélichard, P; Cremers, B; Pruneau, D

    1999-03-01

    1. The present study addresses the differences in binding profiles and functional properties of the human and rat bradykinin (BK) B2 receptor using various kinin receptor peptide derivatives as well as the non-peptide receptor antagonists WIN 64338 (phosphonium, [[4-[[2-[[bis(cyclohexylamino)methylene]amino]-3-(2-naphtalenyl)1- oxopropyl]amino]-phenyl]-methyl]tributyl, chloride, monohydro-chloride), and FR173657 (E)-3-(6-acetamido-3-pyridyl)-N-[-N-[2,4-dichloro-3-[(2-methyl-8-quinoli nyl)oxymethyl]-phenyl]N-methylamino carbonyl methyl] acrylamide. 2. [3H]-BK bound with a similar affinity to membranes of Chinese hamster ovary cells (CHO-K1) expressing the cloned human (hB2-CHO) or rat (rB2-CHO) B2 receptor, human embryonic intestine cells (INT407) expressing the native B2 receptor, human umbilical vein (HUV) and rat uterus (RU). WIN 64338 and FR173657 bound with a 3.8-6.6 fold and 7.0-16.3 fold higher affinity the rat than the human B2 receptor, respectively. The affinity values of BK derivatives as well as non-peptide antagonists were reduced by 6-23 fold in physiological HBSS compared to low ionic strength TES binding buffer. 3. BK (0.01-3000 nM) increased inositol triphosphates (IP3) levels in hB2-CHO, rB2-CHO and INT407 cells. The B2 receptor antagonist, Hoe 140 (D-Arg0-[ Hyp3, Thi5, D-Tic7, Oic8]-BK) at 10(-7) M, significantly shifted to the right the IP3 response curves to BK giving apparent pKB values of 8.56, 9.79 and 8.84 for hB2-CHO, rB2-CHO and INT407 cells, respectively. 4. In human isolated umbilical vein, Hoe 140, D-Arg0-[Hyp3, D-Phe7, Leu8]-BK and NPC 567 had a lower potency in functional assays (pKB 8.18, 5.77 and 5.60, respectively) than expected from their affinity in binding studies (pKi 10.52, 8.64 and 8.27, respectively). 5. FR173657 behaved as a high affinity ligand with pKi values of 8.59 and 9.81 and potent competitive antagonist with pKB values of 7.80 and 8.17 in HUV and RU, respectively. FR173657 bound with a similar affinity the cloned

  9. a Combined Molecular Dynamics and NMR Spectroscopic Protocol for the Conformational Analysis of Oligosaccharides.

    Science.gov (United States)

    Varma, Vikram

    A combined experimental and theoretical protocol for the conformational analysis of oligosaccharides is presented. Three disaccharides, methyl alpha - scD-mannopyranosyl-(1 to 3)-alpha- scD-mannopyranoside, methyl beta- scD-galactopyranosyl-(1 to 4)-beta- scD-glucopyranoside, and propyl beta- scD-2-acetamido -2-deoxy glucopyranosyl-(1 to 3)- alpha- scL-rhamnopyranoside, are used to evaluate a protocol for conformational analysis that makes use of molecular dynamics calculations with the CHARMM force field. Dynamics trajectories computed in vacuo and in water are used to calculate time-averaged NMR parameters such as spin-lattice relaxation times (T_1 ), Nuclear Overhauser Enhancements (NOE), and heteronuclear spin-spin coupling constants (^3J _{rm CH}). The calculated NMR parameters are then compared to experimental values and used to evaluate the computational procedure. The energetically accessible conformations are effectively sampled by the simulations. The method has been extended to the conformational analysis of higher-order oligosaccharides corresponding to the cell-wall polysaccharide of the Streptococcus Group A, and the Shigella flexneri Y O-antigen. The Streptococcus Group A cell-wall polysaccharide is comprised of a backbone of rhamnopyranosyl units connected by alternating alpha- scL-(1 to 3) and alpha- scL -(1 to 2) linkages, to which are attached N-acetyl-beta- scD-glucosamine ( beta- scD-GlcpNAc) residues at the 3 positions of the rhamnose backbone.rm A&rm B^'qquad A^'& rm Bqquad Acr[{-alpha}{-}L{-}Rha {it p}{-}(1to2){-alpha }{-}L{-}Rha{it p} {-}(1to3){-alpha}{ -}L{-}Rha{it p}-(1to2) -alpha-L-Rha{it p}{-}(1 to3){-alpha}{-}L{- }Rha{it p}{-}cr&uparrow(1 to3)&uparrow(1to3)crbeta {-}D{-}&rm Glc{it p }NAcqquadbeta{-}D{-}& rm Glc{it p}NAccr&rm C ^'&rm C] A branched trisaccharide (A^' -(C)B), a tetrasaccharide (A^' -(C)B-A), a pentasaccharide (C^' -B^'-A ^'-(C)B), and two hexasaccharides (C^'-B^ '-A^' -(C)B-A) and (A-(C^')B ^'-A^' -(C)B), have been chosen