Structure of Dermatan Sulfate

Abstract

Abstract The structure of dermatan sulfate-chondroitin sulfate copolymers, isolated from horse aorta, has been examined. It was found that a large proportion of the galactosaminoglycans of this tissue was obtained as a discrete polysaccharide fraction with an l-iduronic acid to d-glucuronic acid ratio of approximately 1:2. This finding together with infrared data indicated that the polymer contained approximately equimolar proportions of the three repeating disaccharide units glucuronosyl-N-acetylgalactosamine 4-sulfate (A), iduronosyl-N-acetylgalactosamine 4-sulfate (B), and glucuronosyl-N-acetylgalactosamine 6-sulfate (C). Degradation of the polymer with chondroitinase-AC yielded, in addition to a large quantity of unsaturated disaccharides, a tetrasaccharide fraction corresponding to an AB sequence in the original polymer. Degradation with testicular hyaluronidase produced a tetrasaccharide of the sequence CA, in addition to higher oligosaccharides corresponding to sequences like ABA or ABC. By sequential degradation of the dermatan sulfate-chondroitin sulfate copolymer with testicular hyaluronidase, β-glucuronidase, and chondroitinase-AC, it was possible to obtain larger fragments containing the bulk of the B units of the polymer. A detailed examination of these fragments revealed that the majority of the B units were located in clusters, particularly in the immediate vicinity of the carbohydrate-protein link. Furthermore, A units were prevalent in positions adjacent to B units, whereas the C units occurred preferentially in the center of the glucuronic acid-containing sections of the chain.