Studies on the chemical constitution of cell-wall lipopolysaccharides from Neisseria perflava

Abstract

Lipopolysaccharides (LPS) were prepared from Neisseria perflava cells and separated into chloroform-soluble and chloroform-insoluble fractions in about equal proportions. The preparations were almost free from protein and contained only traces of peptide material. Both LPS fractions contained 3-deoxyoctulosonic acid (KDO), lipid A, glucose, rhamnose, heptose, glucosamine, galactosamine, ethanolamine, phosphate, and fatty acids. Both fractions had the same proportions of hexosamines and ethanolamine and the same fatty acid components (chiefly β-hydroxymyristic, β-faydroxylauric, octadecenoic, and palmitic acids), but differed markedly in their relative molar proportions of KDO to neutral sugars and of neutral sugars to total fatty acids. Equimolar proportions of hexosamine, ethanolamine, and phosphate in the lipid A moieties suggested that ethanolamine phosphate was linked to glucosamine, probably at the C-6 position. Fatty acids were bound in the LPS by both amide and ester linkages. Heptose units were linked linearly by 1 → 3 glycosidic bonds. About 25% of the glucose units were linked 1 → 3 in a chain; other glucose units were branched as were the rhamnose units. The proportions and arrangement of the heptose, KDO, and lipid A components suggest that the backbone part of the N. perflava lipopolysaccharide is very similar to that found in the Salmonella-Escherichia group.