Structural determination of the O-antigenic polysaccharide from Escherichia coli O166

The O-antigen of the lipopolysaccharide from Escherichia coli O166 has been determined by component analysis together with 1D and 2D NMR spectroscopy techniques. The polysaccharide has pentasaccharide repeating units consisting of d-glucose (1), d-galactose (2) and N-acetyl-d-galactosamine (2) with the following structure:Figure optionsDownload full-size imageDownload as PowerPoint slide In the 1H NMR, spectrum resonances of low intensity were observed. Further analysis of these showed that they originate from the terminal part of the polysaccharide, thereby revealing that the repeating unit has a 3-substituted N-acetyl-d-galactosamine residue at its reducing end.

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