NMR investigation of the 6-deoxy-l-talose-containing O45, O45-related (O45rel), and O66 polysaccharides of Escherichia coli

The structures of the 6-deoxytalose-containing O-specific polysaccharides from the O45 antigen, an O45-related antigen (O45rel), and the O66 antigen (lipopolysaccharides, LPSs) of Escherichia coli were elucidated by chemical characterization and by one- and two-dimensional 1H and 13C NMR spectroscopy. The O45 and O45-related polysaccharides have the following general structure: For the O45 antigen, X is α-d-Fuc p NAc and for the O45-related antigen, X is β-d-Glc p NAc. The structure of the O66 polysaccharide is