Somatic Antigens of Shigella

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Abstract
The O-specific polysaccharide obtained from the lipopolysaccharide of Shigella dysenteriae type 1 (Shigella shiga) by mild acid hydrolysis followed by fractionation on Sephadex G-50 was found to be identical to that described by Morgan's group and was composed of l-rhamnose, d-galactose and N-acetyl-d-glucosamine in a ratio 2:1:1. On the basis of methylation analysis data the polysaccharide was proved to be a linear chain of monosaccharide residues in pyranose forms substituted at position 3, except for that of galactose substituted at position 2. Selective cleavage, based on the N-deacetylation reaction of the polymer, together with determination of linkage configurations by chromic anhydride oxidation showed that the O-specific polysaccharide is built up of repeating tetrasaccharide units whose proposed structure is given below -3)-α-l-Rhap(1–3)-α-l-Rhap(1–2)-α-d-Galp(1–3)-α-d-GlcNAcp(1- where Rhap = rhamnopyranose, Galp = galactopyranose, and GlcNAcp =N-acetyl-glucosamine. The present findings confirmed the considerations of Heidelberger on the substitution patterns of l-rhamnose and d-galactose residues from the results of serological studies.