Changes in chondroitin sulphate structure induced by joint disease

Abstract

Chondroitin sulphate is an important component in articular cartilage, where it occurs at high concentration (40–80 mg/ml) primarily on aggrecan, and also in smaller amounts on the leucine-rich proteoglycans, decorin and biglycan (see Hardingham and Fosang 1992). Chondroitin sulphate contains a repeating disaccharide structure of N-acetylgalactosamine and glucuronate and in aggrecan most of the galactosamine residues carry a single sulphate group in the 4 or 6 position, a small proportion (1–5%) are non-sulphated and an even lower proportion (<1%) may be disulphated, with 4-,6-disulphated galactosamine or some 2-sulphated glucuronate residues. As chondroitin sulphate chains are typically Mr 10–30K they contain 20–60 disaccharides and the incidence of disulphated disaccharides is thus usually less than 1 per chain.