3-O-[3'-O-sulfo-beta-D-galactosyl-(1->3)-N-acetyl-alpha-D-galactosaminyl]-L-serine(1-) residue
3-o-[3'-o-sulfo-beta-d-galactosyl-(1->3)-n-acetyl-alpha-d-galactosaminyl]-l-serine(1-) residue
An <small>L</small>-α amino acid residue obtained by deprotonation of  the sulfate OH group of 3-<em>O</em>-[3'-<em>O</em>-sulfo-β-<small>D</small>-galactosyl-(1→3)-<em>N</em>-acetyl-α-<small>D</small>-galactosaminyl]-<small>L</small>-serine residue; major species at pH 7.3.