Structure of an acidic O-specific polysaccharide of the marine bacterium Pseudoalteromonas sp KMM 634

An acidic O-specific polysaccharide containing D-glucuronic acid (D-GlcA), 2,3-diacetamido-2,3-dideoxy-D-glucuronic acid (D-GlcNAc3NAcA), 2,3-diacetam ido-2,3-dideoxy-D-mannuronoyl-L-alanine (D-ManNAc3NAcA6Ala), and 2-acetamid o-2,4, 6-trideoxy-4-[(S)-3-hydroxybutyramido]-D-glucose (D-QuiNAc4NAcyl) wa s obtained by mild acid degradation of the lipopolysaccharide of the bacter ium Pseudoalteromonas sp. KMM 634 followed by gel-permeation chromatography . The polysaccharide was cleaved selectively with a new solvolytic agent, t rifluoromethanesulfonic acid, to give a disaccharide and a trisaccharide wi th D-GlcNAc3NAcA at the reducing end. The borohydride-reduced oligosacchari des and the initial polysaccharide were studied by GLC-MS and H-1- and C-13 -NMR spectroscopy, and the following structure of the linear tetrasaccharid e repeating unit of the polysaccharide was established: [GRAPHICS]