The Occurrence of a Wide Variety of Dermatan Sulfate-Chondroitin Sulfate Copolymers in Fibrous Cartilage

Abstract

Abstract A large fraction with the properties of a dermatan sulfate-chondroitin sulfate copolymer was obtained from the meniscus (semilunar cartilage) of the human knee joint. This fraction appeared to be homogeneous with respect to charge density, as judged by its behavior on DEAE-cellulose chromatography, but it was further resolved into a number of subfractions by ethanol fractionation, by electrophoresis on cellulose acetate, and by chromatography on Sephadex G-200. Analyses of these subfractions showed that the copolymer was composed of a series of variants whose properties could be accounted for by a gradual variation in the proportion of l-iduronosyl-N-acetylgalactosamine 4-sulfate units and d-glucuronosyl-N-acetylgalactosamine 6-sulfate units. These results indicate that meniscus mucopolysaccharides represent a separate family of mucopolysaccharides that may be specifically adapted to the function of fibrous (collagen-rich) cartilages, and further suggest that any attempt to obtain a mucopolysaccharide sample for structural study must take into consideration this type of polymorphism as well as the scarcity of reliable methods for purification of such mixtures.