Some further observations on the proteoglycans from ox nasal cartilage and pig aorta

Extracts of nasal cartilage prepared by dissociative (3 M MgCl2, 4M guanidinium chloride) procedures usually contain two species of proteoglycan macromolecules with widely differing sedimentation coefficients. This paper describes the isolation of the slower sedimenting component and compares its properties with those of the proteoglycan obtained by disaggregation of the faster of the two sedimenting materials. Additional evidence which illustrates the degradation of proteoglycans by homogenizing procedures (disruptive) is also presented; in particular, fractions obtained by gel permeation chromatography on Sepharose-4B of homogenized extracts, show sedimentation coefficients varying from about 8S to about 24S whereas dissociatively extracted materials treated similarly, give only two types of material with sedimentation coefficients of about 11-12S and 44-47S respectively. Because of the differences between the proteoglycans isolated from cartilage by disruptive and dissociative procedures, the protein-bound chondroitin sulfates obtained from pig aorta by both procedures have been examined; these two preparations are similar with respect to the methods used for characterization. In particular, both materials sediment as single boundaries in the ultracentrifuge with sedimentation coefficients (So20,w) of 5.4S (from homogenized extract) and 5.3S (from dissociative extract); further, their amino acid and carbohydrate compositions are almost identical.