Structural studies of the Escherichia coli O90 O-antigen polysaccharide

The O-specific side-chain of the lipopolysaccharide from Escherichia coli O90 has been investigated using methylation analysis, partial hydrolysis, and NMR spectroscopy as the principal methods. It is concluded that the polysaccharide is composed of tetrasaccharide repeating-units having the following structure. The polysaccharide contains approximately one mole of O-acetyl groups per repeating unit, located on the fucose residue.