Immunochemical studies on Shigella dysenteriae lipopolysaccharides

Immunochemical studies on a polysaccharide from Shigella dysenteriae type 2

The polysaccharide isolated from Shigella dysenteriae type 2, strain NCTC 566, on Smith degradation and graded hydrolysis yielded three oligosaccharides which were characterised using methylation studies. Using homologous rabbit antiserum and the monosaccharides that constituted the polysaccharide and the oligosaccharides isolated from it and the cross-reactions in some type-specific pneumococcal antisera, immunochemical specificities of different sugar groupings in the polysaccharide molecule were determined. These results indicated that N-acetylglucosamine was the immunodominant sugar in the polysaccharide and the oligosaccharide isolated from the Smith-degraded product and having the structure (formula; see text) gave maximum inhibition of the specific precipitation.

Structural studies on a polysaccharide from Shigella dysenteriae type 7

The polysaccharide obtained from the O-somatic antigen of Shigella dysenteriae type 7 (strain NCTC 519/66) contains D-glucose, D-galactose, and 2-acetamido-2-deoxy-D-glucose in the mole ratios of 2:1-1. From the results of methylation, periodate oxidation, graded hydrolysis, and deamination studies, the structure assigned to the repeating unit of the polysaccharide is as follows, (formula: see text) Oxidation studies with chromium trioxide revealed the nature of the anomeric linkages of some of the sugar residues in the polysaccharide.

Somatic antigens of Shigella. The structure of the specific polysaccharide of Shigella newcastle (Sh. flexneri type 6) lipopolysaccharide

The specific polysaccharide was obtained from the lipopolysaccharide of Shigella newcastle by mild acid hydrolysis and further purified by permeation chromatography on Sephadex G-50. It was found to consist of L-rhamnose, 2-acetamido-2-deoxy-D-galactose, D-galacturonic acid residues and O-acetyl groups in the molar ratios of 2:1:1:1. On the basis of 1H and 13C nuclear magnetic resonance spectroscopy, methylation analysis, partial acid hydrolysis, Smith degradation, and chromium trioxide oxidation, the following structure can be assigned to the repeating oligosaccharide unit of the polysaccharide:-4)DGalA(beta 1-3)DGalNAc-(beta 1-2)LAc3Rha(alpha 1-2)LRha(alpha 1-, where GalA = galacturonic acid. GalNAc = N-acetylgalactosamine, Ac3Rha = 3-O-acetylrhamnose. The structural and immunochemical data presented prove that Sh. newcastle lipopolysaccharide belongs to a 'non-classical' type of somatic antigens with acidic O-specific polysaccharide chains.

Somatic antigens of Shigella. The strucuture of the specific polysaccharide chain of Shigella dysenteriae type 5 lipopolysaccharide

The specific polysaccharide was released from Shigella dysenteriae type 5 lipopolysaccharide by mild acidic hydrolysis and then purified by gel chromatography on Sephadex G-50. The polysaccharide was built up of residues of D-mannose, 2-acetamido-2-deoxy-D-glucose, 3-0-(D-1-carboxyethyl)-L-rhamnose (rhamnolactylic acid) and 0-acetyl groups in a ratio 2:1:1:1. On the basis of radiospectroscopy, methylation analysis, Smith degradation, and chromium trioxide oxidation, the repeating oligosaccharide unit of the polysaccharide can be assigned the following structure: (formula: see text) where GlcNAc is 2-acetamido-2-deoxy-D-glucopyranose, Manp is mannopyranose, RhaLcA is rhammolacytic acid and Ac is an acetyl group. The serological properties of Sh. dysenteriae somatic antigens are discussed in relation to the chemical structures of their specific polysaccharides.

Somatic antigens of Shigella. Structural investigation on the O-specific polysaccharide chain of Shigella dysenteriae type-2 lipopolysaccharide

The O-specific polysaccharide obtained from Shigella dysenteriae type-2 lipopolysaccharide by mild acid hydrolysis consisted of N-acetylgalactosamine, N-acetylglucosamine, D-galactose, D-glucose, and O-acetyl group in the ratio of 2:1:1:1:1. A number of oligosaccharides were obtained by deamination of the N-deacetylated polysaccharide and by Smith degradation of the both native and O-deacetylated polysaccharides. The identification of oligosaccharides along with methylation analysis and chromic anhydride oxidation showed that the polysaccharide was built up of the repeating pentasaccharide units whose proposed structure is given below: (see article) Serological properties of Sh. dysenteriae O-specific polysaccharides are discussed.

New sugars from antigenic lipopolysaccharides of bacteria: identification and synthesis of 3-O-[(R)-1-carboxyethyl]-L-rhamnose, an acidic component of Shigella dysenteriae type 5 lipopolysaccharide

A new acidic sugar, 3-O-[(R)-1-carboxyethyl]-L-rhamnose (1), has been identified as a constituent of the O-antigenic lipopolysaccharide of Sh. dysenteriae type 5. The structure of 1 has been established by physico-chemical methods and by synthesis. Alkylation of methyl 2,5-di-O-benzyl-alpha-L-rhamnofuranoside (6) with (S)- or (R)-2-chloropropionic acids, followed by removal of the protecting groups, afforded 3-O-[(R)-1-carboxyethyl]-L-rhamnose (9) and 3-O-[(S)-1-carboxyethyl]-L-rhamnose (10), respectively. The properties of 1 coincide with those of 9.

Selective cleavage of glycosidic linkages: studies with the polysaccharide component of Shigella dysenteriae type 6 lipopolysaccharide

The polysaccharide component obtained from the lipopolysaccharide of Shigella dysenteriae type 6 was subjected to milk hydrolysis with acid, and the products were fractionated on Sephadex G-50. An acidic hexosaminoglycan and a core oligosaccharide fraction were obtained, the former containing D-glucose, D-galactose, 2-acetamido-2-deoxy-D-galactose (in the ratios 1:1:1), and an unidentified acidic component (X). The hexosaminoglycan was N-deacetylated and then hydrolysed and deaminated to give 3-O-(2-amino-2-deoxy-beta-D-galactopyranosyl)-D-galactose (1), identified as the N-acetyl derivative (2), and 2,5-anhydro-3-O-(6-O-alpha-D-galactopyranosyl-alpha-D-glucopyranosyl)talitol (3). On the basis of the structure of 2 and the methylation-analysis data for the polysaccharide and 3, together with that for the determination of linkage configurations by chromic anhydride oxidation, the hexosaminoglycan is considered to have the repeating structure (see article).

Somatic antigen of Shigella dysenteriae type 3. Structural features of specific polysaccharide chain

On mild acid hydrolysis of lipolysaccharide from Shigella dysenteriae type 3 the O-specific polysaccharide (hapten) was obtained which appeared to be acidic branched hexosaminoglycan. The repeating unit of this polysaccharide represents a pentasaccharide composed of two D-galactose residues, N-acetyl-D-galactosamine, D-glucose and unidentified acidic component. On the basis of methylation analysis, periodate oxidation, partial acid hydrolysis and chromic anhydride oxidation it is concluded that the structure of the chemical repeating unit of polysaccharide is (see article) where Glcp is glucopyranose, Galp is galactopyranose, Galf is galactofuranose, GalNAcp is 2-acetamido-2-deoxygalactopyranose and where the configuration of galactofuranoside glycosidic linkage and the structure of the acidic monosaccharide A are not known.