Biosynthesis of Connective Tissue Polysaccharides

ABSTRACT The biosynthesis of chondroitin sulphate exemplifies the formation of connective tissue polysaccharides. Six different glycosyltransferases participate: a chain-initiating xylosyltransferase, two galactosyltransferases, two glucuronosyltransferases, and an N-acetylgalactosaminyltransferase. Some of their properties are discussed, particularly their substrate specificities determined with small oligosaccharide acceptors of well-defined structure. Purification of these enzymes is in its early stages and has been hampered by the membrane-bound nature of most of them. Xylosyltransferase, which is the most soluble, has been purified over I 000-fold by chromatography on an affinity matrix of Sepharose-bound Smith-degraded cartilage proteoglycan.