Structural studies of the O-antigenic polysaccharides from Shigella dysenteriae type 3 and Escherichia coli O124, a reinvestigation

From biosynthetic considerations this should also be the biological repeating unit. The structures of the repeating units also explain the previously observed cross-reactivity between the strains and to E. coli O164, which only differs in the terminal sugar residue that is lacking the (R)-1-carboxyethyl group.