Structure of the O-specific polysaccharide from the lipopolysaccharide of Aeromonas hydrophila strain K691 containing 4-acetamido-4,6-dideoxy-d-glucose.

The O-specific polysaccharide (OPS) was isolated from the lipopolysaccharide of Aeromonas hydrophila strain K691 and studied by chemical methods and 1H and 13C NMR spectroscopy, including 2D 1H,1H COSY, TOCSY, NOESY, 1H-detected heteronuclear 1H,13C HSQC, and HMBC experiments. It was found that the O-specific polysaccharide was built up of pentasaccharide repeating units composed of β-GlcpNAc, 2-O-acetylated α-Rhap, and β-Quip4NAc residues. The following structure of the OPS was established: →3)-α-l-Rha2OAc-(1→3)-β-d-GlcNAc-(1→3)-α-l-Rha2OAc-(1→3)-β-d-GlcNAc-(1→2)-β-d-Qui4NAc-(1→.