Chemical and Metabolic Heterogeneity of a Bovine Aorta Chondroitin Sulfate‐Dermatan Sulfate Proteoglycan

1 A proteoglycan containing about 80% chondroitin sulfate and dermatan sulfate in a ratio of 75:25 was isolated and purified from bovine arterial tissue. This proteoglycan behaved as a single compound by several criteria of homogeneity. On incubation in vitroof arterial tissue segments with [35S]sulfate under appropriate conditions the 35S-radioactivity was incorporated into the proteoglycan. 2 Degradation of the polysaccharide component of the labelled proteoglycan by testes hyaluronidase produces dermatan [35S]sulfate and a series of saccharide fragments ranging from disaccharides to decasaccharides. The tetrasaccharide fraction was found to contain iduronic acid (IduUA) as well as glucuronic acid (GlcUA), indicating a copolymeric structure of chondroitin–and dermatan–sulfate units. The IduUA/GlcUA-ratio of oligosaccharides increased with increasing chain length. The sulfate content of oligosaccharides containing either chondroitinor dermatan-sulfate units as the predominant component did not differ significantly, but the specific radioactivity of the sulfate ester groups of the dermatan-sulfate units was about three times higher than those of the chondroitin-sulfate units, thus providing evidence for a metabolic heterogeneity of these two polysaccharides. 3 The molecular weight of the proteoglycan is approximately 2× 106. A randomly coiled shape for the molecule can be deduced from light scattering measurements. It consists of a protein core carrying about 80 polysaccharide chains which are attached to the protein by O-seryl and O-threonyl glycosidic linkages.