Structural studies of the O-antigen polysaccharide from the enteroinvasive Escherichia coli O173.

The structure of the O-antigen polysaccharide (PS) from Escherichia coli O173 has been investigated. Sugar and methylation analyses, electrospray ionisation mass spectrometry together with 1H, 31P and 13C NMR spectroscopy were the main methods used. The structure of the pentasaccharide repeating unit of the PS was found to be: [formula: see text] By treatment with 48% HF the phosphoric diester linkage was cleaved together with the glycosidic linkage of the fucosyl group, rendering a tetrasaccharide with the structure: alpha-D-Glcp-(1-->2)-beta-D-Glcp-(1-->3)-beta-D-GlcpNAc-(1-->3)-D-Glc.