Dermatan sulfate-chondroitin sulfate copolymers from ambilical cord. Isolation and characterization

Dermatan sulfate-chondroitin sulfate copolymers have been isolated from human umbilical cord as a major galactosaminoglycan component of this tissue. The galactosaminoglycan fraction was obtained from this tissue by papain [EC 3.4.22.2] digestion followed by precipitation with cetylpyridinium chloride in a yield of 700 mg per 100 g of dry tissue. Ethanol fractionation resolved 4-5 subfractions differing in relative content of L-iduronic acid and D-glucuronic acid. No galactosaminoglycan containing either solely L-iduronic acid or D-glucuronic acid was obtained. The copolymeric structure of the material in each subfraction was demonstrated by analysis of oligosaccharide fragments obtained by chondroitinase-AC [EC 4.2.2.5] digestion. All the polymers contained repeating disaccharide units, D-glucuronosyl-N-acetylgalactosamine, D-glucuronosyl-N-acetylgalactosamine 4-sulfate, D-glucuronosyl-N-acetyl-galactosamine 6-sulfate, and L-iduronosyl-N-acetylgalactosamine 4-sulfate, of which D-glucuronosyl-N-acetylgalactosamine 6-sulfate and L-iduronosyl-N-acetylgalactosamine 4-sulfate were predominant. Both iduronic acid- and glucuronic acid-containing units were arranged in clusters. The presence of a considerable amount of nonsulfated disaccharide units was noted. The copolymers show extensive polydispersity in electrophoresis on cellulose acetate and gel chromatography on Sephadex G-200.