Structural Elucidation of the O‐Antigenic Polysaccharide from Escherichia coli O44: H18

Abstract
The O‐antigen polysaccharide of the lipopolysaccharide from the enteroaggregative Escherichia coli O44:H18 has been investigated. Sugar and methylation analysis, 1H‐ and 13C‐NMR spectroscopy revealed that the polysaccharide is composed of pentasaccharide repeating units. The sequence of sugar residues was determined by use of two‐dimensional nuclear Overhauser effect spectroscopy and heteronuclear multiple bond correlation experiments. The structure of the repeating unit of the O‐antigen from Escherichia coli O44:H18 is as follows.