Analysis of the proteolytic degradation products of hyaline cartilage proteoglycans.

The proteolytic degradation products of nasal hyaline cartilage proteoglycans produced by polymorphonuclear leukocyte lysosomal enzymes were investigated. The protein content of the degradation products is 7.0-8.6% corresponding to a peptide chain of 24-28 amino acids and the relative molecular mass of the total fragment is M(r) = 37,600-39,200. On an average, each proteoglycan fragment contains two chondroitin-sulphate chains (M(r) = 22,000-22,400), every fourth fragment contains a keratan sulphate chain (M(r) = 7000-7200) and every seventh to eighth contains an O-glycosidic oligosaccharide. The results of the disaccharide analysis show that the galactosaminoglycan chains contain 76.2-83.6% chondroitin-4-sulphate, 12.9-19.4% chondroitin-6-sulphate, 3.5-3.8% chondroitin and no dermatan sulphate. Since composition and relative molecular mass of the chondroitin sulphate and keratan sulphate chains from the degradation products resemble those from native proteoglycans, it is suggested that the degradation of the proteoglycans occurs by proteinases that attack preferably the chondroitin sulphate region of the core protein.