The structure of the polysaccharide moiety of Rhodopseudomonas sphaeroides ATCC 17023 lipopolysaccharide

Abstract

The chemical structure of the polysaccharide moiety of the lipopolysaccharide of Rhodopseudomonas sphaeroides ATCC 17023 was established. Mild acetic acid hydrolysis of isolated lipopolysaccharide, followed by preparative high-voltage paper electrophoresis afforded three oligosaccharides. They were characterized by chemical and physicochemical studies to be: GlcA(α1→4)dOclA8P, Thr(6′) GlcA(α1→4)GlcA and GlcA(α1→4)dOclA, where GlcA is d-glucuronic acid and dOclA is 3-deoxy-d-manno-octulosonic acid. Carboxyl-reduction of the lipopolysaccharide followed by acid hydrolysis gave a trisaccharide: GlcA(α1→4)Glc(α1→4)G1c, showing the presence of three residues of glucuronic acids in the O-specific chain and indicating that only two of them are reducible by NaBH₄. The linkage between the polysaccharide and lipid A was shown to be through a single 1,4-linked residue of dOclA attached by a 2,6′-linkage to the lipid A moiety.