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A S Shashkov

Publications and source records attributed to A S Shashkov.

At least 127 records · Page 7Linked to original sources
PubMed1997

Structure of the O-specific polysaccharide of the bacterium Proteus mirabilis O13 containing a novel component: an amide of D-galacturonic acid with N(epsilon)-(1-carboxyethyl)lysine.

An acidic O-specific polysaccharide was obtained by mild degradation of the lipopolysaccharide of the bacterium Proteus mirabilis O13 and found to contain D-galactose, 2-acetamido-2-deoxy-D-glucose, and N(epsilon)-(1-carboxyethyl)-N(alpha)-(D-galacturonoyl)lysine. On the basis of full acid hydrolysis and 1H- and 13C-NMR spectroscopy, including two-dimensional correlation spectroscopy (COSY), H-detected heteronuclear 1H, 13C multi-quantum coherence (HMQC), and rotating-frame nuclear Overhauser effect spectroscopy (ROESY), the following structure of the branched trisaccharide repeating unit of the polysaccharide was established [structure: see text]

Amides↗
PubMed1997

Anionic polymers in cell walls of gram-positive bacteria.

Information on the prevalence, compositions, and structures of anionic carbohydrate-containing polymers of cell walls of Gram-positive bacteria is summarized. The data suggest that these polymers are important for normal functioning of bacterial cells and require further studies. Structural data on teichoic acids found in the literature published over the last few years are discussed. This is a very diverse class of polymers whose structure-specific pathways of degradation were studied and NMR spectra were examined. Unique comprehensive tables of 13C-NMR spectroscopic data (mainly obtained by the authors) on these polymers are given in the Appendix. Other tables summarize data on teichuronic acids, sugar-phosphate polymers, acid polysaccharides, and structural variants of bonds between acid polysaccharides and peptidoglycans known from the literature. Functions of anionic polymers and their possible chemotaxonomic applications are discussed.

Anions↗
PubMed1997

Structural and immunochemical studies on the O-specific polysaccharide of Proteus penneri strain 15.

On the basis of sugar analysis and 1H- and 13C-NMR spectroscopy, it was shown that the O-specific polysaccharide of Proteus penneri strain 15 has a trisaccharide repeating unit, including an acetal-linked pyruvic acid residue, and is structurally identical to the capsular polysaccharide of Proteus vulgaris strain ATCC 49990. Serological studies supported this conclusion and demonstrated the presence in the homological antiserum of both anti-core and anti-O chain antibodies reacting with a lipopolysaccharide (LPS) epitope containing N-acetylglucosamine and galactose residues.

Animals↗
PubMed1997

Structure of a neutral O-specific polysaccharide of the bacterium Proteus mirabilis O24.

Lipopolysaccharide of the bacterium Proteus mirabilis O24 was found to have a neutral O-specific polysaccharide chain containing D-galactose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-2-deoxy-D-galactose in ratios 1:2:1. On the basis of 1H- and 13C-NMR spectroscopy, including two-dimensional correlation spectroscopy (COSY), H-detected 1H, 13C heteronuclear multiple-quantum coherence (HMQC), and nuclear Overhauser effect spectroscopy (NOESY), the following structure of the branched tetrasaccharide repeating unit of the O-specific polysaccharide was established: -->3)-beta-D-GlcpNAc-(1-->4)-beta-D-GalpNAc-(1-->4)-beta-D-GlcpNAc-(1--> [formula: see text] beta-D-Galp.

Carbohydrate Conformation↗
PubMed1997

NMR spectroscopic elucidation of the structure of a glycerol teichoic acid-like O-specific polysaccharide of the bacterium Hafnia alvei strain PCM 1199.

The structure of the acidic O-specific polysaccharide of a Gram-negative bacterium, H. alvei strain PCM 1199, was studied by NMR spectroscopy including two-dimensional correlation spectroscopy (COSY), total correlation spectroscopy (TOCSY), nuclear Overhauser effect spectroscopy (NOESY), 1H, 13C heteronuclear single-quantum coherence (HSQC), 1H, 13C heteronuclear multiple-bond correlation (HMBC), and one-dimensional 1H, 31P heteronuclear multiple-quantum coherence (HMQC) experiments. It was found that the polysaccharide contains D-galactose, 2-acetamido-2-deoxy-D-glucose, 4-acetamido-4,6-dideoxy-D-glucose, glycerol, and phosphate in the ratios 1:2:1:1:1, as well as O-acetyl groups in non-stoichiometric amounts. The polysaccharide is similar in structure to teichoic acids of Gram-positive bacteria and has the following structure of the repeating unit: 3)-beta-D-Galp-(1-->3)-alpha-D-GlcpNAc-(1-->3)-beta-D-Quip4NAc-(1- ->1)-Gro- 3-P-(O--> [formula: see text] beta-D-GlcpNAc [formula: see text] The O-specific polysaccharide of H. alvei PCM 1199 is structurally related to another teichoic acid-like O-specific polysaccharide of H. alvei PCM 1205 studied by us earlier.

Carbohydrate Sequence↗
PubMed1997

[Synthesis of oligosaccharides related to the HNK-1 antigen. Synthesis of selectively protected allyl-3-o-methyl(beta-D- glucopyranosyl)uronate-beta-D-galactopyranoside].

The glycosylation of several mono- and dihydroxyl glycosyl acceptors based on allyl beta-D-galactopyranoside with completely acylated glucuronyl bromides under the Helferich reaction conditions was studied in order to develop a method for the preparative synthesis of selectively protected disaccharide beta-D-GlcA-(1-->3)-beta-D-Gal in a form that can be used for further preparation of corresponding glycosyl donors and spacerated derivatives. We found that 1,2-orthoesters were the major primary products of the reaction, and their further conversion into isomeric glycosides depended on pH and can be regulated by the type of molecular sieves used. When Acid Washed Molecular Sieves AW 300 were used, glycosides were predominantly synthesized. No selective formation of the (1-->3)-bound disaccharide was observed upon glycosylation of glycosyl acceptors with 2,3- and 3,4-diol groupings. This (1-->3)-bound disaccharide was most efficiently synthesized by glycosylation of allyl 4,6-O-benzylidene-2-O-benzoyl-beta-D-galactopyranoside with pivaloylated glucuronyl bromide. With acetylated or benzoylated glucuronyl bromides or with pivaloyl glucuronyl imidate, this galactoside can also be glycosylated but with a lower yield of the target (1-->3)-bound disaccharide and lower glycosylation regioselectivity.

Allyl Compounds↗
PubMed1996

Structure of the O-specific polysaccharide of Hafnia alvei PCM 1222 containing 2-aminoethyl phosphate.

The O-specific polysaccharide of H. alvei strain PCM 1222 has a branched hexasaccharide repeating unit containing D-galactose, L-rhamnose, D-ribose, D-galacturonic acid, and 2-acetamido-2-deoxy-D-glucose in the ratios 1:2:1:1:1, as well as 2-aminoethyl phosphate (EtNP) and O-acetyl groups in nonstoichiometric amounts. The polysaccharide was modified by carboxyl reduction, O-deacetylation, and dephosphorylation with 48% hydrofluoric acid, the last reaction being accompanied by removal of the lateral residue of beta-galactofuranose. The modified polysaccharides were studied by methylation analysis and 1H and 13C NMR spectroscopy, including 2D correlation spectroscopy (COSY), H-detected 1H,13C and 1H,31P heteronuclear multiple-quantum coherence (HMQC), 1D NOE, 2D rotating-frame NOE spectroscopy (ROESY), and 2D combined total correlation spectroscopy (TOCSY) and ROESY (TORO). The following structure of the O-deacetylated polysaccharide was established: [formula: see text] In different batches of the polysaccharide, the content of EtNP varied from 0.35 to 0.55 and that of the O-acetyl groups from 0.05 to 0.4 per repeating unit. It was tentatively suggested that the O-acetyl group is located at position 4 of a rhamnosyl residue.

Aminoethylphosphonic Acid↗
PubMed1996

Structural and serological studies of the O-specific polysaccharide of the bacterium Proteus mirabilis O10 containing L-altruronic acid, a new component of O-antigens.

An acidic O-specific polysaccharide from the lipopolysaccharide of Proteus mirabilis O10 contains 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2-deoxy-D-galactose, D-galacturonic acid, and L-altruronic acid, the last-named sugar having not been found hitherto in O-antigens. Structure of a branched tetrasaccharide repeating unit of the polysaccharide was established by 1H and 13C NMR spectroscopy, including two-dimensional COSY and rotating-frame NOE spectroscopy. The lateral L-altruronic acid residue plays the immunodominant role in manifestation of the O10 specificity of Proteus, whereas a disaccharide fragment of the main chain in common with the O-specific polysaccharide of P. mirabilis O43 provides the one-way serological cross-reactivity between anti-O10 serum and O43-antigen.

Antibodies, Bacterial↗
PubMed1996

Structural study and serological characterisation of the O-specific polysaccharide of Hafnia alvei PCM 1185, another Hafnia O-antigen that contains 3,6-dideoxy-3-[(R)-3-hydroxybutyramido]-D-glucose.

The O-specific polysaccharide of H. alvei strain PCM 1185 contains D-glucose, D-glucuronic acid, 2-acetamido-2-deoxy-D-glucose, and 3,6-dideoxy-3-[(R)-3-hydroxybutyramido]-D-glucose (Qui3NAcyl) in the ratios 2:1:1:1 as well as O-acetyl groups. On the basis of sugar and methylation analyses of the polysaccharide before and after chemical modifications (O-deacetylation, carboxyl reduction, Smith degradation), as well as 1H and 13C NMR spectroscopy, including 1D sequential, selective spin-decoupling, 2D homonuclear and 13C,1H heteronuclear correlation spectroscopy (COSY), and 2D rotating-frame NOE spectroscopy, it was found that the polysaccharide has a pentasaccharide repeating unit with the following structure: [formula: see text] with O-acetyl groups present in nonstoichiometric amounts, mainly at position 2 of GlcA and position 6 of GlcNAc or lateral Glc. Serological study showed that H. alvei strain PCM 1185 can be placed in a new serotype D and that an O-acetyl group can be a part of its epitope.

Carbohydrate Conformation↗
PubMed1996

Structure of a new N-acetylisomuramic acid-containing O-specific polysaccharide of Proteus penneri strains 19 and 35.

O-Specific polysaccharides, together with oligosaccharide products of their degradation, were isolated by GPC after mild acid delipidation of lipopolysaccharides of Proteus penneri strains 19 and 35. The polysaccharides had the same trisaccharide repeating unit containing one residue each of D-galactose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-3-O-[(S)-1-carboxyethyl]-2-deoxy-D-glucose (N-acetylisomuramic acid). On the basis of 1D and 2D 1H and 13C NMR spectroscopy, including 2D correlation spectroscopy (COSY), rotating-frame NOE spectroscopy (ROESY), and H-detected heteronuclear 1H,13C multiple-quantum coherence (HMQC), the following structure of the repeating unit was established: [formula: see text]. The oligosaccharide products formed by cleavage of the glycosidic linkage of GlcNAc represent a chemical trisaccharide repeating unit of the polysaccharide and its oligomer homologs. The ease of hydrolysis of the polysaccharide is associated with the closeness of the glycosyl group and the lactic acid residue in N-acetylisomuramic acid. The polysaccharides studied are structurally related to the O-specific polysaccharides of P. penneri strains 62 and 71 studied by us earlier.

Carbohydrate Conformation↗
PubMed1996

Synthesis and structural studies of branched 2-linked trisaccharides related to blood group determinants.

A series of trisaccharide glycosides, Fuc-(1 reversible 2)-beta-Gal-(1 reversible 3)-beta-X-OMe (X = GlcNAc, Glc, 2-deoxy-Glc) related to the blood group determinant Le(d) have been synthesised both as their alpha- and beta-Fuc anomers together with the component disaccharide starting compounds. The conformational properties of the six trisaccharides together with their parent disaccharides have been investigated by NMR spectroscopy (proton and carbon chemical shifts and proton NOEs) in combination with computer modeling using the Monte Carlo approach and the HSEA force field using the GEGOP programme. The interaction between the terminal fucose unit and the reducing unit was probed by substitution of bulky NAc group with hydroxyl and deoxy substituents, respectively. Compounds with severe steric interactions were identified by the non-additivity of their carbon chemical shifts. This was subsequently confirmed by the detailed conformational assessment by NOE spectroscopy and computer modeling. The most severe contacts arose in the alpha-L-Fuc derivatives, whereas the beta-linked L-Fuc derivatives only in one case exhibit severe steric interaction as probed by the NMR parameters.

Carbohydrate Conformation↗
PubMed1996

The O-specific polysaccharide chain of Campylobacter fetus serotype B lipopolysaccharide is a D-rhamnan terminated with 3-O-methyl-D-rhamnose (D-acofriose).

An O-specific polysaccharide was liberated from Campylobacter fetus subsp. fetus serotype B lipopolysaccharide by mild acid hydrolysis followed by gel chromatography. This polysaccharide was found to contain D-rhamnose and 3-O-methyl-D-rhamnose (D-Rha3Me, D-acofriose) in a ratio of approximately 24:1, as well as lipopolysaccharide core constituents. The structure of the polysaccharide was studied by 1H-NMR and 13C-NMR spectroscopy, which included two-dimensional COSY, rotating-frame NOE spectroscopy (ROESY), and computer-assisted analysis of the 13C-NMR spectrum. Methylation analysis using [2H3]methyl iodide and Smith degradation followed by GLC/MS of the derived acetylated oligosaccharide-alditols was used to determine the location of D-acofriose. The O-specific polysaccharide is linear, consists on average of 12 disaccharide repeating units, and is terminated by a residue of D-acofriose. The following structure of the D-rhamnan chain was established: [sequence: see text]

Campylobacter fetus↗
PubMed1996

Structures of new acidic O-specific polysaccharides of the bacterium Proteus mirabilis serogroups O26 and O30.

The polysaccharide chains of the lipopolysaccharides of the Proteus mirabilis serogroups O26 and O30 were studied using sugar and methylation analysis and 1H and 13C NMR spectroscopy, including two-dimensional correlation spectroscopy and rotating-frame NOE spectroscopy. The polysaccharides were found to be acidic due to the presence of D-galacturonic acid and its amide with L-lysine in serogroup O26 or D-glucuronic acid in serogroup O30, and the structures of their tetrasaccharide repeating units were established. The O26-specific polysaccharide is structurally and serologically related to the O-specific polysaccharide of P. mirabilis O28, which includes amides of D-GalA with L-lysine and L-serine [Radziejewska-Lebrecht, J. et al. (1995) Eur. J. Biochem. 230, 705-712].

Carbohydrate Conformation↗
PubMed1996

Triterpene and steroid saponins isolated from two Melilotus species.

Four new triterpene saponins of the oleanan series-melilotosides I, II, III, IV and nonglycosylated soyasapogenol B have been isolated from roots of Melilotus albus Medik. (Leguminosae) and four steroid saponins were isolated from M. tauricus (Bieb.) ser. seeds. The chemical structure of the saponins and of their aglycone was proved based on chemical transformations and spectral data. Melilotoside I has the structure of 3-O-[a-L-arabinopyranosyl] soyasapogenol B, melilotoside II that of 3-O-[beta-D-galactopyranosyl-(1-->2)-O-alpha-L-arabinopyranosyl] soyasapogenol B, melilotoside III that of 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-beta-D-galactopyranosyl-(1-->2)-O -alpha-L-arabinopyranosyl] soyasapogenol B, and melilotoside IV that of 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-arabinopyranosyl-(1- ->3)]- O-beta-D-galactopyranosyl-(1-->2)-O-alpha-L-arabinopyranosyl soyasapogenol B. The steroid saponins have been identified as 3-O-beta-D-glucopyranoside-diosgenin (V); 3-O-alpha-L-rhamnopyranosyl (1-->2)-[alpha-L-rhamnopyranosyl(1-->3)-O-beta-D-glucopyranoside- diosgenin (VI),26-O-beta-D-glucopyranoside (25R)-furost-5-ene 3beta,22alpha, 26-triol (VII), and 3-O-alpha-L-rhamnopyranosyl(1-->4)-alpha-O-beta-D- glucopyranoside(25R)-furost-5-ene 3beta,22alpha,26-triol-26-O-beta-D- glucopyranoside (VIII).

Fabaceae↗
PubMed1996

Characterization of the lipopolysaccharides from Rhizobium meliloti strain 102F51 and its nonnodulating mutant WL113.

Lipopolysaccharides from the Rhizobium meliloti wild-type strain 102F51, which is effective in symbiosis with alfalfa, and from the nonnodulating mutant WL113, defective in root hair adhesion, derived thereof, were isolated and comparatively analyzed. Both preparations were composed of galactose, glucose, glucuronic acid, galacturonic acid, glucosamine, 3-deoxyheptulosaric acid, and 2-keto-3-deoxyoctonic acid as the major sugar constitutents. After a modified methylation analysis (consisting of the following consecutive steps: methylation, carboxyl reduction, remethylation, mild acid hydrolysis, reduction, and trideuterio-methylation), all of the 3-deoxyheptulosaric and some of the 2-keto-3-deoxyoctonic acid residues were converted into their corresponding 3-deoxyalditol derivatives, which carried trideuteriomethyl groups at positions C-2, C-4, and C-6. Another part of the permethylated 3-deoxyoctitol was also found as 2,5,6- and 2,6,8-tri-O-trideuteriomethyl derivatives. NMR data obtained with the separated oligosaccharides and the results of methylation analysis indicated that the majority of 2-keto-3-deoxyoctonate was present in the fraction of permethylated disaccharide alditols, namely as 6-O-CD3-alpha Glc(1-->5)3-deoxyoctitol, 6-O-CD3-beta GlcNMeAcyl(1-->4)-3-deoxyoctitol, and as the permethylated trisaccharide alditol, alpha GalA(1-->3)-[6-O-CD3]-beta-Glc(1-->5)-[4-O-CD3]-3-deoxyoctitol. The presence of trideuteriomethyl groups at C-4 of both 3-deoxyalditols and at C-6 of the glucosaminyl or glycosyl residues indicated the linkage points of the released acid-labile ketosidic substituents, such as 3-deoxyheptulosarate and 2-keto-3-deoxyoctonate, in these oligosaccharides. The main differences between the preparations from the wild-type 102F51 and its mutant strain WL 113 were found in the higher content (in strain 102F51) of the following oligosaccharides: alpha-glucuronosyl(1-->4)2-keto-3-deoxyoctonate and alpha-galacturonosyl-(1-->3)alpha-glucosyl-(1-->5)2-keto-3-deoxyoc tonate and in the decreased content of beta-glucosaminyl(1-->4)2-keto-3-deoxy-octonate.

Lipopolysaccharides↗
PubMed1996

Analysis of the enzymatic cleavage (beta elimination) of the capsular K5 polysaccharide of Escherichia coli by the K5-specific coliphage: reexamination.

The capsular K5 polysaccharide of Escherichia coli is the receptor of the capsule-specific coliphage K5, which harbors an enzyme that degrades the capsular K5 polysaccharide to a number of oligosaccharides. Analysis of the degradation products using gel permeation chromatography, the periodate-thiobarbituric acid and bicinchoninic acid reactions, and nuclear magnetic resonance spectroscopy showed that the major reaction products are hexa-, octa-, and decasaccharides with 4,5-unsaturated glucuronic acid (delta4,5GlcA) at their nonreducing end. Thus, the bacteriophage enzyme is a K5 polysaccharide lyase and not, as we had reported previously, an endo-N-acetylglucosaminidase.

Bacterial Capsules↗