Structure of an acidic O-specific polysaccharide of Pseudoalteromonas haloplanktis type strain ATCC 14393 containing 2-acetamido-2-deoxy-d- and -l-galacturonic acids and 3-(N-acetyl-d-alanyl)amino-3,6-dideoxy-d-glucose

An acidic O-specific polysaccharide was obtained from the lipopolysaccharide of Pseudoalteromonas haloplanktis ATCC 14393 and found to contain d-galactose, 3-(N-acetyl-d-alanyl)amino-3,6-dideoxy-d-glucose (d-Qui3NdAlaAc), 2,4-diacetamido-2,4,6-trideoxy-d-glucose (d-QuiNAc4NAc), 2-acetamido-2-deoxy-d- and -l-galacturonic acids (d- and l-GalNAcA), and O-acetyl groups. On the basis of Smith degradation and 1H and 13C NMR spectroscopic studies, including 2D COSY, TOCSY, NOESY, 1H, 13C HMQC, and HMBC experiments, the following structure of the pentasaccharide repeating unit of the polysaccharide was established:→4)-α-l-GalpNAcA-(1→3)-β-d-QuipNAc4NAc-(1→2)-β-d-Quip3NdAlaAc-(1→4)-α-d-GalpNAcA-(1→4)-α-d-Galp2,6Ac2-(1→where O-acetylation of the galactose residue at each position is partial (50–70%).