The structure of the O-polysaccharide of the Pseudoalteromonas rubra ATCC 29570T lipopolysaccharide containing a keto sugar

The structure of the phenol-soluble polysaccharide from Pseudoalteromonas rubra type strain ATCC 29570(T) has been elucidated using H-1 and C-13 NMR spectroscopy, including 2D COSY, TOCSY, gNOESY, ROESY, H-1, C-13 gHMQC and gHMBC experiments. It is concluded that the trisaccharide repeating unit of the polysaccharide has the following structure: -->4)-alpha-L-GalpNAm3AcA-(1-->3)-alpha-Sugp-(1-->4)-beta-D-GlcpNAc3NAcylA-(1--> where Sug is 2-acetamido-2,6-dideoxy-D-xylo-hexos-4-ulose, Am is acetirnidoyl and Acyl is a malic acid residue, which is O-acetylated in similar to 70% of the units. (C) 2005 Elsevier Ltd. All rights reserved.