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A S Shashkov

Publications and source records attributed to A S Shashkov.

At least 163 records · Page 9Linked to original sources
PubMed1995

The structure of the O-specific polysaccharide from Thiobacillus sp. IFO 14570, with three different diaminopyranoses forming the repeating unit.

The O-specific polysaccharide, liberated by mild acid hydrolysis of the lipopolysaccharide (LPS-P) from Thiobacillus sp. IFO14570 as isolated from the phenol phase after phenol-water extraction, is shown to have a linear trisaccharide repeating-unit containing three different diamino sugars, namely 2,4-diacetamido-2,4-dideoxyglucuronic acid, 2-acetamidino-4-acetamido-2,4,6-trideoxyglucopyranose, and 2,3-diacetamido-2,3-dideoxyglucuronic acid in the molar ratio of 1:1:1. On the basis of 1H and 13C spectroscopy, including 2D COSY and coherent transfer (RCT)COSY, 1D NOE in the difference mode, and 2D rotating frame NOE(ROESY) the sequence, the type of substitution, and the position of the acetamidino group could be determined. These experiments allowed formulation of the following structure for the O-specific polysaccharide, although the depicted D configuration of the three sugar residues is not yet proven: [structure: see text]

Amino Sugars↗
PubMed1995

Structure of microcin C51, a new antibiotic with a broad spectrum of activity.

The structure of microcin C51, a new antibiotic produced by E. coli, has been determined. This antibiotic was shown to be a 1.18 kDa nucleotide peptide. It consists of a heptapeptide with formylmethionine as the N-terminus and a C-terminal asparagine linked with nebularin-5'-monophosphate through the three-methylene bridge. The OH-group of threonine is substituted. The peptide chain of microcin C51 synthesized on ribosomes is the longest among the known biologically active nucleotide peptides.

Amino Acid Sequence↗
PubMed1995

Structure of simusan, a new acidic exopolysaccharide from Arthrobacter sp.

Simusan, a major exopolysaccharide produced by an ethanol-utilizing Arthrobacter sp. strain CE-17, contains D-glucose, D-mannose, D-galactose, L-rhamnose, D-glucuronic acid, and pyruvic acid in the ratios approximately 3:2:1:1:1:1 as well as O-acyl groups (presumably (presumably residues of acetic and palmitic acid). On the basis of chemical modifications of the polysaccharide, solvolysis with anhydrous hydrogen fluoride resulting in a penta- and an octa-saccharide fragment, Smith degradation, and 1H and 13C NMR analysis, the following structure of the repeating unit was established: [formula: see text] It is suggested that at least one of the glucose residues and the galactose residue are O-acetylated.

Arthrobacter↗
PubMed1995

[Structure of an acidic polysaccharide found in a bacteriolytic complex of lysoamidase].

A structural study of an acidic polysaccharide, a component of the lysoamidase bacteriolytic complex has been carried out. Analysis of the monosaccharide composition of the original polysaccharide, of the product of carboxyl groups reduction and of the 13C-NMR and 1H-NMR spectra of the original and the O-deacetylated polysaccharides using two-dimensional NMR spectroscopy has made it possible to establish the structure of the repeating trisaccharide unit of the polysaccharide as follows: [formula: see text] where ManNAcA and GalNAcA are 2-acetamido-2-deoxymannuronic acid and 2-acetamido-2-deoxygalacturonic acid, respectively. Also small amount of a neutral polysaccharide containing of rhamnose is present in the lysoamidase preparation.

Bacteria↗
PubMed1995

[Triterpene glycosides from Hedera taurica. XIII. Structure of taurosides St-I1 and St-I2 from Crimean ivy stems].

The taurosides, St-I1 and St-I2, isolated from the stems of Crimean ivy Hedera taurica Carr. (Araliaceae), were shown to be the known glycoside, 3-O-[beta-D-glucopyranosyl-(1-->2)-O-alpha-L-arabinopyranosyl]-28- O-[alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-bet a-D- glucopyranosyl]hederagenin, and a new glycoside, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranosyl]-28-O-[a lpha -L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-beta-D- glucopyranosyl]hederagenin, respectively.

Carbohydrate Conformation↗
PubMed1994

Teichuronic acid of the cell wall of Actinoplanes brasiliensis.

The cell wall of Actinoplanes brasiliensis INA 3802 contains a teichuronic acid of unusual structure, as determined in a nondestructive way by 1H- and 13C-NMR spectroscopy. The polysaccharide comprises six tetrasaccharide units of the following composition: -->6)-alpha-D-Glcp-(1-->4)-beta-D-2,3-diacetamido- 2,3-dideoxyGlcpA-(1-->4)-alpha-D-2,3-diacetamido-2,3-dide oxyGlcp-(1-->4)-beta- D-2,3-diacetamido-2,3-dideoxyManpA. A polymer of such structure has not heretofore been reported for procaryotic cell walls.

Actinomycetales↗
PubMed1994

Structure of the O16 polysaccharide from Escherichia coli O16:K1: an NMR investigation.

The polysaccharide moiety of the O16 antigen (lipopolysaccharide) consists of D-glucopyranose, D-galactofuranose, L-rhamnopyranose, and 2-acetamido-2-deoxy-D-glucopyranose in the molar ratios 1:1:1:1. It is O-acetylated with one acetyl group per repeating unit. One- and two-dimensional NMR spectroscopy of the polysaccharide before and after O-deacetylation showed that the O16 polysaccharide has the structure [formula: see text]

Carbohydrate Conformation↗
PubMed1994

Structure of the O83-specific polysaccharide of Escherichia coli O83:K24:H31.

The polysaccharide moiety of the O83 antigen (lipopolysaccharide, LPS) consists of D-glucose, D-galactose, 2-acetamido-2-deoxy-D-glucose, and D-glucuronic acid in the molar ratios 1:2:1:1. Methylation analysis of the polysaccharide and derived oligosaccharides as well as one- and two-dimensional 1H and 13C NMR spectroscopy of the polysaccharide at pD 1 and 6 showed that the O83 polysaccharide has the primary structure-->6)-alpha-D-Glc p-(1-->4)-beta-D-Glc pA-(1-->6)-beta-D-Gal p-(1-->4)-beta-D- Gal p-(1-->4)-beta-D-Glc pNAc-(1-->.

Antigens, Bacterial↗
PubMed1994

The structure of the O-specific polysaccharide of Salmonella arizonae O21 (Arizona 22) containing N-acetylneuraminic acid.

The O-specific polysaccharide of S. arizonae O21 was found to contain 2-acetamido-2-deoxy-D-glucose, 2-acetamidino-2,6-dideoxy-L-galactose, N-acetylneuraminic acid, and O-acetyl groups. On the basis of 1H and 13C NMR studies of the intact and O-deacetylated polysaccharide and oligosaccharide fragments obtained by solvolysis with anhydrous hydrogen fluoride, partial methanolysis and partial hydrolysis, it was concluded that the O-specific polysaccharide has the following structure: [formula: see text]

Carbohydrate Conformation↗
PubMed1994

The structure of the O-specific polysaccharide of Hafnia alvei strain 1216.

The O-specific polysaccharide of Hafnia alvei strain 1216 is composed of D-galactose, D-glucuronic acid, 2-acetamido-2-deoxy-D-glucose, 3,6-dideoxy-3-[(R)-3-hydroxybutyramido]-D-glucose, and O-acetyl groups in the ratios 1:1:2:1:1. On the basis of sugar and methylation analyses of the intact and chemically degraded (O-deacetylated, carboxyl-reduced, Smith-degraded) polysaccharide and 1H and 13C NMR spectroscopy, including 2D shift-correlated (COSY, relayed COSY, 13C, 1H-COSY) and 1D NOE spectroscopy, it was concluded that the O-antigen is built up of linear pentasaccharide units having the following structure: [formula: see text]

Carbohydrate Conformation↗
PubMed1994

The structure of the cyclic enterobacterial common antigen (ECA) from Yersinia pestis.

Two antigenic acidic polysaccharides related to enterobacterial common antigen (ECA) were isolated from a vaccine strain of a pathogenic microorganism Yersinia pestis. The low molecular weight polysaccharide (LMP) is composed of equal amounts of 2-acetamido-2-deoxy-D-mannuronic acid, 4-acetamido-4,6-dideoxy-D-galactose (Fuc4NAc), and 2-amino-2-deoxy-D-glucose which is partially N- and partially 6-O-acetylated. The structure of the trisaccharide repeating unit was established by analyses of LMP and the completely N-acetylated LMP (LMP-NAc) using 1H and 13C NMR spectroscopy, including 2D COSY and 1D NOE spectroscopy. Deamination of LMP with nitrous acid gave a set of oligomers terminated with 2,5-anhydromannose and ranging from tri- to dodeca-saccharides, thus indicating a random distribution of free amino groups. FABMS analyses of LMP and LMP-NAc showed that LMP consists mainly of the cyclic tetramer of the trisaccharide repeating unit together with a small amount of the cyclic trimer and a very small amount of the cyclic pentamer and has, thus, the following structure: [formula: see text] where R is Ac or H (approximately 1:1), R' is Ac or H (approximately 1:4), and n = 4 (major), 3, 5 (minor). Small proportions of the linear trimer and the linear tetramer were also detected in the preparations. The high molecular weight polysaccharide is linear and has the same (or a very similar) repeating unit as LMP.

Antigens, Bacterial↗
PubMed1994

The inner core region of Yersinia enterocolitica Ye75R (0:3) lipopolysaccharide.

The inner-core region of the lipopolysaccharide of an UDPGalNAc-4-epimerase-deficient mutant of Yersinia enterocolitica 0:3, designated as Ye75R, was investigated using methylation analysis, 1D-13C-NMR and 2D-13C-NMR and 1H-NMR, as well as 31P-NMR, fast-atom-bombardment mass spectrometry (FAB MS) and FAB MS/MS in positive and negative modes. The isolated core heptasaccharide (OS) was composed of 2 units D-glucose, 3 units LD-heptose and 1 unit each of DD-heptose and 3-deoxy-D-manno-octulosonic acid. Methylation analysis indicated that OS was highly branched with terminal location of the two glucoses and the DD-heptose unit, which was partially (to about 40%) phosphorylated at C7. These combined studies allowed us to formulate the structure of the inner core region as shown in Scheme 1. The substitution of the 7-position of the terminally linked DD-heptose unit by phosphate could be recognized by MS characterization of permethylated DD-heptose-7-phosphate (alditol acetate) and the extent of the substitution by the ratio of the two well separated 1H signals of DD-heptose in 500-MHz 1H-NMR. Negative FAB MS of OS also indicated the presence of smaller amounts of two hexasaccharides, differing from OS in lacking either one terminal unit of D-glucose or of the terminal DD-heptose, and additionally of a pentasaccharide lacking two heptosyl units, namely the terminal DD-heptose and and the subterminal LD-heptose. The presence of the smaller oligosaccharides in the OS fraction was also recognized by the methylation analysis.

Carbohydrate Conformation↗
PubMed1994

Structure of the capsular polysaccharide and the O-side-chain of the lipopolysaccharide from Acetobacter methanolicus MB 70, and of oligosaccharides resulting from their degradation by the bacteriophage Acm6.

Acetobacter methanolicus MB 70 was shown to be related to the type strain of this species MB 58/4 (IMET 10945) having the same galactan-->2)-beta-D-Gal f-(1-->3)-beta-D-Gal p-(1-->as the capsular polysaccharide (CPS) and the O-side-chain of the lipopolysaccharide (LPS). Additionally, a glucan built up of the disaccharide repeating unit-->6)-alpha-D-Glc p-(1-->2)-alpha-D-Glc p-(1-->was identified in strain MB 70. In the CPS, the polymers were present in the ratio approximately 1:1, whereas the glucan preponderated in the LPS. Bacteriophage Acm6 specific to A. methanolicus MB 70 hydrolysed selectively the glucan component of both CPS and LPS. Structural elucidation of the resulting oligosaccharides led to the identification of the phage-associated depolymerase as an endo-alpha-(1-->6)-D-glucopyranoside hydrolase.

Acetobacter↗