The molecule is zwitterionic form of O-(3-O-D-galactosyl-N-acetyl-beta-D-galactosaminyl)-L-serine arising from transfer of a proton from the carboxy to the amino group; major species at pH 7.3. It is a tautomer of an O-(3-O-D-galactosyl-N-acetyl-beta-D-galactosaminyl)-L-serine.
(2S)-3-[(2R,3R,4R,5R,6R)-3-acetamido-5-hydroxy-6-(hydroxymethyl)-4-[(3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxyoxan-2-yl]oxy-2-azaniumylpropanoate