Structural characterization of the antigenic O-chain of the lipopolysaccharide of Escherichia coli serotype O65

The antigenic O-polysaccharide moiety of the lipopolysaccharide produced by Escherichia coli serotype O65 was investigated by composition, methylation, base hydrolysis, periodate oxidation, mass spectrometric methods, and by 1D and 2D NMR spectroscopy. The O-polysaccharide had [α]D+108° (water) and is a high-molecular-weight unbranched linear polymer of repeating pentasaccharide units composed of 1:1:1:1:1 d-galacturonic acid (d-GalA), d-galacturonamide (d-GalANH2), 2-acetamido-2-deoxy-d-glucose (d-GlcNAc), 2-acetamido-2-deoxy-d-galactose (d-GalNAc), and 3-acetamido-3,6-dideoxy