The molecule is alpha-Neu5Ac-(2->8)-Neu5Ac in which the configuration at the anomeric carbon atom of the residue at the reducing end is beta. It has a role as an epitope.
(2S,4S,5R,6R)-5-acetamido-6-[(1S,2R)-2-[(2S,4S,5R,6R)-5-acetamido-2-carboxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]oxan-2-yl]oxy-1,3-dihydroxypropyl]-2,4-dihydroxyoxane-2-carboxylic acid