Protein-polysaccharide complexes from adult human tracheal cartilage

Several reports have described the isolation of protein-polysaccharide complexes (proteoglycans) from human costal and articular cartilage (Rosenberg, Johnson Kroz & Buddecke, 1967) corresponding to the protein- polysaccharide light (PPL) and heavy (PPH) fractions isolated previously from bovine nasal cartilage (Gerber, Franklin & Schubert, 1960).The PPL fraction has been the protein-polysaccharide most studied so far and when isolated from human adult costal cartilage its composition differs con- siderably from that of bovine origin (Pedrini, 1969).A major difference in the complexes from the two sources is the greater keratan sulphate content of the human PPL fraction and this is in keeping with the high proportion of this glycosaminoglycan found in adult human hyaline cartilages (Mathews & Glagov, 1966).Thus the study of protein-poly.saccharides from mature human cartilage, rather than from bovine tissues, may yield much needed information about the role ofkeratan sulphate in the extracellular matrix.This communication is concerned with the characterization of proteinpolysaccharide complexes from mature human tracheal cartilage, a tissue that has not previously been extensively studied.The keratan sulphate content ofthis tissue attains maximum values by the beginning of the fourth decade and thereafter remains constant (Mason, 1970).Tracheas were collected from 20 subjects (aged 45-75 years) within 24h ofdeath and stored at -20°C in 80% (v/v) ethanol until required.After separa- tion of the cartilage rings from surrounding tissue they were pooled, homogenized in ethanol and recovered as a dry cartilage powder (Schubert, 1965).Portions of this preparation were then extracted by high-speed homogenization in water (Schubert, 1965), a procedure that includes a second homo- genization of the insoluble material, after which the extraction of soluble protein-polysaccharide is virtually complete (cf.Rosenberg et al. 1965).Soluble protein-polysaccharide from the tracheal cartilage was then fractionated into PPL and PPH fractions by high-speed centrifugation (Schubert, 1965).