Structural studies of the O-antigenic polysaccharide from Escherichia coli O139

Abstract

The structure of the O-antigenic from Escherichia coli O139 has been investigated with the aid of NMR spectroscopy, and sugar and methylation analyses. The sequence of the sugar residues was determined by NOESY and heteronuclear-multiple-bond-connectivity NMR experiments. The polysaccharide is composed of heptasaccharide repeating units containing 0.6 mol O-acetyl groups/repeating unit. The following structure is concluded, where Rha represents rhamnose. →3)-α-D-GlcpNAc-(1→3)-α-L-Rhap-(1→4)-α-D-GalpA- (1→2)-α-L-Rhap-(1→3)-α-L-Rhap-(1→2)-α-L-Rhap-(1→ 3 ↑ ↑ β-D-Glcp.