PROTEIN-POLYSACCHARIDES OF ARTICULAR EPIPHYSEAL PLATE AND COSTAL CARTILAGES

1. 1. The yields of protein-polysaccharides obtained from bovine fetal articular, epiphyseal plate and porcine costal cartilage and their content of uronic acid, hexosamine, sialic acid, protein hydroxyproline were determined. The ability of the protein-polysaccharides to inhibit the precipitation of calcium phosphate in vitro was also studied, both before and after degradation of the protein-polysaccharides by enzymes extracts of epiphyseal plate cartilage. 2. 2. Yields and compositions of protein-polysaccharides from the diverse hyaline cartilages were similar, indicating that there are, in the narrow age range studied, in the different cartilages and in the different species of animals, remarkable similarities in the chemical nature of the hyaline cartilages with respect to their content of protein-polysaccharides. Differences in composition are manifest, however, when compared with calf nasal cartilages or nucleus pulosus. 3. 3. Most of the protein-polysaccharides inhibited the precipitation of calcium phosphate from solution. If the protein-polysaccharides are first degraded by enzyme extracts obtained from cartilage, the inhibitory activity of the protein-polysaccharides is abolished in the range of concentrations studied. These phenomena are discussed in relation to calcification of cartilage. © 1969.