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).