The molecule is a disaccharide that is D-mannopyranose in which the hydroxy group at position 4 has been converted into the corresponding beta-D-galactopyranosyl derivative. It derives from a beta-D-mannose and a beta-D-galactose.
(2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-[(2R,3S,4R,5S,6R)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol