Structure of the O16 polysaccharide from Escherichia coli O16:K1: an NMR investigation.

The polysaccharide moiety of the O16 antigen (lipopolysaccharide) consists of D-glucopyranose, D-galactofuranose, L-rhamnopyranose, and 2-acetamido-2-deoxy-D-glucopyranose in the molar ratios 1:1:1:1. It is O-acetylated with one acetyl group per repeating unit. One- and two-dimensional NMR spectroscopy of the polysaccharide before and after O-deacetylation showed that the O16 polysaccharide has the structure --> 6)-alpha-D-Glcp-(1 --> 3)-alpha-L-Rhap-(1 --> 3)-alpha-D-GlcpNAc-(1 --> 2)-beta-D-Galf-(1 --> 2 \ OAc