Novel proteoglycan linkage tetrasaccharides of human urinary soluble thrombomodulin, SO4-3GlcA beta 1-3Gal beta 1-3(+/- Sia alpha 2-6)Gal beta 1-4Xyl

O-linked sugar chains with xylose as a reducing end linked to human urinary soluble thrombomodulin were studied. Sugar chains were Liberated by hydraz inolysis followed by N-acetylation and tagged with 2-aminopyridine. Two fra ctions containing pyridylaminated Xyl as a reducing end were collected. The ir structures were determined by partial acid hydrolysis, two-dimensional s ugar mapping combined with exoglycosidase digestions, methylation analysis, mass spectrometry, and NMR as SO4-3GlcA beta 1-3Gal beta 1-3(+/-Sia alpha 2-6)Gal beta 1-4Xyl. These sugar chains could bind to an HNK-1 monoclonal a ntibody. This is believed to be the first example of a proteoglycan linkage tetrasaccharide with glucuronic acid 3-sulfate and sialic acid.