Occurrence of chondroitin sulfate E in glycosaminoglycan isolated from the body wall of sea cucumber Stichopus japonicus

Glycosaminoglycan was isolated from the body wall of sea cucumber Stichopus japonicus by a method consisting of enzymatic digestion, gel filtration, and ion-exchange chromatography. One gram of sea cucumber glycosaminoglycan was composed of 2.50 mmol of sulfate, 0.47 mmol of N-acetylgalactosamine (GalNAc), 0.53 mmol of glucuronic acid (GlcA), 1.73 mmol of fucose, and a small amount of peptide. When mildly hydrolyzed with 0.1 N H2SO4, this glycosaminoglycan released two products, one consisting of fucose plus sulfate and the other of fucose only. Partially hydrolyzed glycosaminoglycan thus obtained was composed of sulfate, GalNAc, GlcA, and fucose at a molar ratio of 3:2:2:1. Partially hydrolyzed glycosaminoglycan was easily digested with chondroitinase AC II. In ion-exchange chromatography, the digest exhibited four sharp peaks whose retention times agreed with those of unsaturated 0-(delta Di-0S), mono-(delta Di-4S and delta Di-6S), and di-(delta Di-SE) sulfated disaccharide, respectively. The disaccharide unit of sea cucumber glycosaminoglycan was composed of 22.4% chondroitin sulfate E, 11.2% chondroitin, 10.4% chondroitin 4-sulfate, and 56.0% chondroitin 6-sulfate.