Isolation and some structural analyses of a proteodermatan sulphate from calf skin

A proteodermatan sulphate was isolated from 0.15 M-NaCl and 0.45 M-NaCl extracts of newborn-calf skin. The proteoglycan was separated from collagen and hyaluronic acid by precipitation with cetylpyridinium chloride and CsCl-density-gradient centrifugation. Further purification was performed by ion-exchange, affinity and molecular-sieve chromatography. The proteoglycan bound to concanavalin A-Sepharose in 1 M-NaCl. It gave a positive reaction with periodic acid/Schiff reagent and contained 8.3% of uronic acid. The dermatan sulphate, the only glycosaminoglycan component, was composed of 74% iduronosylhexosamine units and 26% glucuronosylhexosamine units. The Mr was assessed to be 15000-20000 by gel chromatography. The core protein was found to be a sialoglycoprotein that had O-glycosidic oligosaccharides with N-acetylgalactosamine at the reducing termini. The molar ratio of oligosaccharide chains to dermatan sulphate was approx. 3:1. From these results the proposed structure of proteodermatan sulphate is: one dermatan sulphate chain (average Mr 17500), three O-glycosidic oligosaccharide chains and probably N-glycosidic oligosaccharide chain(s) bound to one core-protein molecule (Mr 55000).