bacterial polysaccharide structure
Mild acid degradation of the lipopolysaccharide of the bacterium Idiomarina zobellii, type strain KMM 231(T), with aq 2% HOAc at 100degreesC, yielded an oligosaccharide, which represents one repeating unit of the O-polysaccharide. A polysaccharide was obtained by mild base degradation of the lipopolysaccharide. The following structure of the O-polysaccharide was elucidated by H-1 and C-13 NMR spectroscopy of the oligosaccharide and base-degraded lipopolysaccharide, including COSY, TOCSY, ROESY, H-1, C-13 HSQC, HSQC-TOCSY and HMBC experiments:--> 3)-alpha-D-Quip4N-(1 --> 4)-alpha-D-GlcpA-(1 --> 6)-alpha-D-GlcpNAc-(l --> 4)-alpha-L-GulpNA-(1 --> 3)-beta-D-FucpNAc-(1 -->The O-polysaccharide is distinguished by the presence of two unusual amino sugars, 4-amino-4,6-dideoxy-D-glucose (D-Qui4N) and 2-amino-2-deoxy-L-guluronic acid (L-GulNA), both having the free amino group. The unexpectedly high acid lability of the glycosidic linkage of 2-acetamido-2,6-dideoxy-D-galactose (D-FucNAc) could be associated with the presence of a free amino group adjacent to the site of attachment of FucNAc to Qui4N. (C) 2003 Elsevier Ltd. All rights reserved.