Structure of an O-acetylated acidic O-specific polysaccharide of Proteus vulgaris O46

An acidic O-specific polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Proteus vulgaris O46 and studied by chemical methods (O-deacetylation, sugar and methylation analyses, partial solvolysis) and 1H and 13C NMR spectroscopy. Solvolysis of the O-deacetylated polysaccharide with trifluoromethanesulfonic acid resulted in a α-d-GlcpNAc-(1→3)-d-GlcA disaccharide that demonstrated the usefulness of this reagent for selective cleavage of heteropolysaccharides. The following structure for the polysaccharide was established:→4)-α-d-Glcp6Ac(1→3)-β-d-GlcpA4Ac-(1→3)-α-d-GlcpNAc-(1→3)-β-d-GlcpA4Ac-(1→where the degree of O-acetylation is ∼65% at position 6 of Glc and 80–95% at position 4 of GlcA residues.