Structural elucidation of the O-antigenic polysaccharides from Escherichia coli O21 and the enteroaggregative Escherichia coli strain 105

The structure of the O-antigen polysaccharide of the lipopolysaccharide from an enteroaggregative Escherichia coli (strain 105) has been elucidated, using primarily one-dimensional and two-dimensional NMR experiments. The sequence of residues was deduced with heteronuclear multiple-bond correlation and NOESY experiments. The structure of the repeating unit of the polysaccharide from the enteroaggregative E. coli is as follows: [GRAPHICS] The structure of the O-antigen from enteroaggregative E. coli strain 105 was shown to be identical with that of E. coli O21 by sugar and methylation analyses as well as by H-1-NMR and C-13-NMR spectroscopy.