The molecule is a branched amino pentadecasaccharide comprising beta-D-galactosyl, beta-D-glucosyl and 2,5-anydro-D-mannose residues linked sequentially (1->4) and (1->6), to the galactosyl residue of which are linked (1->3) two units of beta-D-Gal-(1->4)-beta-D-Glc-(1->6)-[alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)]-beta-D-GlcNAc themselves linked (1->3). Obtained by depolymerisation of the group B Streptococcus (GBS) type III capsular polysaccharide during which process the 2,5-anhydro-D-mannose residue is formed from the original reducing-end N-acetyl-glucosaminyl residue (PMID:28439022).
(2S,4S,5R,6R)-5-acetamido-2-[(2S,3R,4S,5S,6R)-2-[(2R,3S,4S,5S)-2-[[(2R,3R,4R,5S,6R)-5-[(2S,3R,4S,5S,6R)-4-[(2S,3R,4R,5S,6R)-3-acetamido-6-[[(2R,3R,4R,5S,6R)-5-[(2S,3R,4S,5S,6R)-4-[(2S,3R,4R,5S,6R)-3-acetamido-5-[(2S,3R,4S,5S,6R)-4-[(2S,4S,5R,6R)-5-acetamido-2-carboxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]oxan-2-yl]oxy-3,5-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-6-[[(2R,3R,4R,5S,6R)-3,4-dihydroxy-6-(hydroxymethyl)-5-[(2S,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxyoxan-2-yl]oxymethyl]-4-hydroxyoxan-2-yl]oxy-3,5-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-3,4-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxymethyl]-5-[(2S,3R,4S,5S,6R)-4-[(2S,4S,5R,6R)-5-acetamido-2-carboxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]oxan-2-yl]oxy-3,5-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-4-hydroxyoxan-2-yl]oxy-3,5-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-3,4-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxymethyl]-5-formyl-4-hydroxyoxolan-3-yl]oxy-3,5-dihydroxy-6-(hydroxymethyl)oxan-4-yl]oxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]oxane-2-carboxylic acid