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.