Chondroitin ABC lyase digestion of an ascidian dermatan sulfate. Occurrence of unusual 6-O-sulfo-2-acetamido-2-deoxy-3-O-(2-O-sulfo-α-l-idopyranosyluronic acid)-β-d-galactose units

A dermatan sulfate-like glycosaminoglycan was isolated from the body of the ascidian Ascidia nigra (J. Biol. Chem. 270: 31027–31036, 1995). 1H NMR and fast atom bombardment mass spectrometry (FAB-MS) spectra of the tetra and disaccharides formed by chondroitin ABC lyase digestion support the proposed repeating disaccharide structure for this glycosaminoglycan, [→ 4)-α-l-IdoA(2SO4)-(1 → 3)-β-d-GalNAc(6SO4)-(1 →, which differ from mammalian dermatan sulfate in its sulfation at both 2-position of the α-l-iduronic acid and the 6-position of the N-acetyl-β-d-galactosamine residue.