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A S Shashkov

Publications and source records attributed to A S Shashkov.

At least 181 records · Page 10Linked to original sources
PubMed1994

The structure of the O-specific polysaccharide of Citrobacter O16 containing glycerol phosphate.

The O-specific polysaccharide, obtained by mild acid degradation of Citrobacter O16 lipopolysaccharide, consists of D-glucose, D-galactose, 2-acetamido-2-deoxy-D-galactose, glycerol and phosphate in the ratios 2:2:2:1:1. Selective cleavage of the polysaccharide was carried out by Smith degradation, N-deacetylation-deamination and dephosphorylation with 48% hydrofluoric acid, which was accompanied by unexpected splitting of one of the glycosidic linkages. The structures of the oligosaccharides thus obtained were established using 1H- and 13C-NMR spectroscopy, including one-dimensional NOE, two-dimensional rotating-frame NOE, homonuclear and heteronuclear 13C, 1H correlation spectroscopy, and, for the Smith degradation product, positive- and negative-ion-mode fast-atom-bombardment MS and MS/MS with collision-induced dissociation. On the basis of these data and the results of methylation analysis, it was concluded that the O-specific polysaccharide has the following repeating unit structure: [formula: see text]

Carbohydrate Conformation↗
PubMed1994

Structural and immunochemical studies on O-specific polysaccharide of Proteus penneri strain 14.

The complete structure of the O-antigen of Proteus penneri strain 14, containing D-alanine and L-alanine was established using methylation, solvolysis with anhydrous hydrogen fluoride, partial acid hydrolysis, 1H- and 13C-NMR spectroscopy. The role of partial structures of the pentasaccharide repeating unit in manifesting serological specificity and cross-reactivity of this strain with some other bacteria is discussed.

Alanine↗
PubMed1994

[Selectin receptors. 1. Synthesis of SiaLe(a) and SiaLe(x) tetrasaccharides and their polymeric conjugates].

Spacer-armed tetrasaccharide Neu5Ac alpha 2-3Gal beta 1-3(Fuc alpha 1- 4)GlcNAc-sp (SiaLe(a), sp = OCH2CH2CH2NH2) was synthesized from 6-BnGlcNAc-sp with 6-BnAc3GalSEt, Bn3FucSEt, and Ac4Neu5AcSEt methyl ester as glycosyl donors. The final glycosylation of the trisaccharide bearing unprotected 2-, 3-, and 4-hydroxyls of galactose moiety was promoted with NIS-TfOH in MeCN, yield of alpha-sialoside being 48% (29% as the NGlcNAc-SEt derivative). A mixture of beta-connected (2-3) and (2-4) lactones was obtained as a side product (30%). Tetrasaccharide Neu5Ac alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc-sp (SiaLe(x)) was synthesized by a similar way starting from 6-Bn-3-MeOBnGlcNAc-sp; yield of alpha-sialylation was 74%, neither N-SEt nor beta-connected lactones were isolated. Condensation of the spacered tetrasaccharides with poly(4-nitrophenylacrylate) gave N-substituted polyacrylamide-type polymers. Biotinylated probes and polymers modified with phosphatidylethanolamine (strong immunogens) were also obtained. The unsubstituted and labelled polymeric derivatives were used for studying selectins and other lectins, as well as production and epitope characterization of monoclonal antibodies against sialooligosaccharides.

Carbohydrate Sequence↗
PubMed1994

[Selectin receptors. 2. Synthesis of HSO3-3'Le(a)--a sulfated ligand of the cell adhesion molecule, E-selectin].

HSO3-3'Gal beta 1-3(Fuc alpha 1-4)GlcNAc beta 1-O(CH2)3NH2 was synthesized by selective sulfation (Py.SO3/Py, O degree C) of a protected trisaccharide Lea derivative bearing unsubstituted hydroxyls at C2 and C3 of the galactose moiety, BdGal beta 1-3(Bn3Fuc alpha 1-4)6-BnGlcNAc beta 1-O(CH2)3NHCOCF3, followed by convenient deprotection. A monosaccharide derivative, HSO3-3Gal beta 1-O(CH2)3NH2, was also obtained in a similar way. Coupling of the aminopropyl glycosides with poly(4-nitrophenylacrylate) gave rise to polyacrylamide (PAA) conjugates; biotinylated probes of the Sug-PAA-biotin type were obtained as well.

Carbohydrate Sequence↗
PubMed1994

[1,5-poly(ribitol phosphate) with tetrasaccharide substituents in the cell wall of Agromyces fucosus ssp. Hippuratus].

Cell walls of Agromyces fucosus ssp. hippuratus VKM Ac-1352T and VKM Ac-1353 contain teichoic acids of identical structure. The polymer is of a 1.5-poly(ribitol phosphate) type. Each ribitol phosphate residue is substituted at C-4(2) by tetrasaccharide having the following structure: alpha-L-Rhap(1-->3)-alpha-L-Rhap-(1-->3)-beta-D-GlcpNAc-(1-- >2)- alpha-L-Rhap-(1-->. The teichoic acid chain is made up by 12-13 repeating units. No structurally identical polymer of the procaryotic cell wall has so far been reported.

Actinomyces↗
PubMed1994

[An anionic polysaccharide from the cell wall of Actinoplanes brasiliensis INA 3802].

The cell wall of Actinoplanes brasiliensis INA 3802 contains a polysaccharide which has an unusual structure. The peculiar structure of the polymer has been established by a nondestructive procedure which included 1H- and 13C-NMR spectroscopy. The polysaccharide consists of six tetrasaccharide links having the following composition -->6(alpha-D-Glc rho-(1-->4)-beta-D-Clc rho 2,3NAcA-(1-->4)-alpha-D-Clc rho 2,3NAc-(1-->4)-beta- D-Man rho 2,3NAcA-(1-->. No structurally identical polymer of the procaryotic cell wall has so far been reported.

Actinomyces↗
PubMed1993

Synthesis of 2,3-di-O-glycosyl derivatives of methyl alpha- and beta-D-glucopyranoside.

The syntheses are described of 2,3-di-O-glycosyl derivatives of methyl alpha- and beta-D-glucopyranoside having alpha-D-manno-, beta-D-galacto-, alpha-L-rhamno-, alpha-L-fuco-, and beta-L-fuco-pyranosyl substituents at O-2 and O-3. The syntheses involved glycosylation of methyl 4,6-O-benzylidene-alpha- (24) and -beta-D-glucopyranoside (21), and substituted derivatives of 21 bearing 2-O-(2,3,4,6-tetra-O-benzoyl-alpha-D-mannopyranosyl)-, -(2,3,4,6-tetra-O- acetyl-beta-D-galactopyranosyl)-, -(2,3,4,-tri-O-benzoyl-alpha-L- rhamnopyranosyl)-, and -(2,3,4-tri-O-benzoyl-beta-L-fucopyranosyl) groups.

Carbohydrate Conformation↗
PubMed1993

Studies of O-specific polysaccharide chains of Pseudomonas solanacearum lipopolysaccharides consisting of structurally different repeating units.

The structures of the O-antigenic polysaccharide chains of lipopolysaccharides of a number of Pseudomonas solanacearum strains were elucidated mainly with the help of methylation analysis and 13C NMR spectroscopy, including a computer-assisted 13C NMR-based analysis. Six structurally distinct but related polysaccharides were identified. They have a backbone which is built up of three L-rhamnopyranosyl residues and one 2-acetamido-2-deoxy-D-glucopyranosyl residue, and is unsubstituted or substituted with a residue of L-xylopyranose or L-rhamnopyranose as a monosaccharide side chain. The lipopolysaccharides of most of the strains contain polysaccharide chains consisting of at least two structurally different types of repeating units. Three of the polysaccharides are common to more than one strain.

Carbohydrate Conformation↗
PubMed1993

Erythritolteichoic acid in the cell wall of Glycomyces tenuis VKM Ac-1250.

The cell wall of Glycomyces tenuis VKM Ac-1250 contains the teichoic acid unusual for bacteria. The teichoic acid is a 1,4-poly(erythritol phosphate) chain composed of about 23 erythritol phosphate units, four or five of which have a 2-acetamido-2-deoxy-alpha-D- glucopyranosyl substituent at C2(3) of erythritol. The polymer contains O-acetyl groups. Its structure was identified by chemical analysis as well as 1H-NMR and 13C-NMR spectroscopy. No teichoic acid containing a poly(erythritol phosphate) chain has yet been found in Gram-positive bacteria.

Actinomycetales↗
PubMed1993

Structure of the O-specific polysaccharide of the O23 antigen (LPS) from Escherichia coli O23:K?:H16.

The polysaccharide moiety of the O23 antigen (lipopolysaccharide) consists of D-glucose, D-galactose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-2-deoxy-D-galactose in the molar ratios 2:1:2:1. Methylation analysis of the polysaccharide as well as one- and two-dimensional 1H and 13C NMR spectroscopy of the polysaccharide and a trisaccharide obtained by Smith degradation showed that the O23 polysaccharide has the primary structure [formula: see text].

Carbohydrate Conformation↗
PubMed1993

Structural comparison of the O4-specific polysaccharides from E. coli O4:K6 and E. coli O4:K52.

Two distinct forms of the O4 antigen (LPS) from E. coli were analysed by 1H and 13C NMR spectroscopy. Both consisted of D-glucose, L-rhamnose, 2-acetamido-2,6-dideoxy-L-galactose (L-FucNAc), and 2-acetamido-2-deoxy-D-glucose. Their structures were found to be [formula: see text]. In the O4-specific polysaccharide from E. coli O4:K3, O4:K6, and O4:K12, X is alpha-D-Glcp. In the O4 specific polysaccharide from E. coli O4:K52, the rhamnose residue is not substituted (X = H).

Carbohydrate Conformation↗
PubMed1993

Structural analysis of O4-reactive polysaccharides from recombinant Escherichia coli. Changes in the O-specific polysaccharide induced by cloning of the rfb genes.

In previous studies it had been shown that lipopolysaccharide from O4-specific recombinant Escherichia coli, had serological reactivities and a chemical composition that differed from wildtype O4 LPS [Haraguchi, G.E., Zähringer, U., Jann, B., Jann, K., Hull, R.A. & Hull, S.I. (1991) Microb. Pathog. 10, 351-361]. Here we present the structural elucidation of the O-specific moieties from lipopolysaccharides of some of the recombinant strains obtained in previous studies. Compositional analysis, methylation, chemical reactions and NMR spectroscopy showed that, during genetic manipulations (recombination, cosmid cloning, plasmid subcloning), a gradual structural change in the O-specific polysaccharides was observed in the recombinant strains. These changes comprised of an alteration in the position of glucose (side chain) substitution, a change in the anomeric configuration of the main-chain N-acetylglucosamine and an exchange of alpha-L-rhamnopyranose for beta-D-galactofuranose. The relevance of these results for lipopolysaccharide cloning and lipopolysaccharide biosynthesis are discussed.

Carbohydrate Sequence↗