The molecule is a polysaccharide derivative comprised of a [2)-alpha-L-Rhap(III)-(1->2)-alpha-L-Rhap(II)-(1->3)-alpha-L-Rhap(I)-(1->3)-beta-D-GlcpNAc-(1->] tetrasaccharide repeat modified by addition of acetyl groups to 40% of the O-6 positions of the GlcNAc residue and to either O-3 or O-4 of many of the Rha(III) residues (30% to O-3; 20% to O-4). The structure provided is representative of that in Shigella flexneri serotype Y and shows the most common repeating unit. It has a role as an antigen.
[(2R,3S,4R,5R,6R)-5-acetamido-4-[(2S,3R,4R,5S,6S)-4-[(2S,3R,4R,5R,6S)-3-[(2S,3R,4R,5S,6S)-4-acetyloxy-3,5-dihydroxy-6-methyloxan-2-yl]oxy-4,5-dihydroxy-6-methyloxan-2-yl]oxy-3,5-dihydroxy-6-methyloxan-2-yl]oxy-3,6-dihydroxyoxan-2-yl]methyl acetate