Composition and calcium binding of proteinpolysaccharides of calf nasal septum and scapula

Proteinpolysaccharide (PP-L) of resting and ossifying zones of calf scapular cartilage and of calf nasal septum cartilage was extracted with aqueous 0.15 M KCl and fractionated into a series of products: PP-L3, PP-L4, PP-L5, PP-L6. An additional proteinpolysaccharide fraction, PP-L2, was extracted from the cartilage residues with hydroxylamine. Differences in chemical composition among corresponding proteinpolysaccharides obtained from the three cartilage sources were, in general, small. The calcium binding capacity of the PP-L, PP-L2, and PP-L3 samples, as measured by equlibrium dialysis, appeared to reflect principally their uronic acid and exchangeable sulfate contents. Application of a cation exchange technique indicated that PP-L from resting and ossifying zones of scapular cartilage had similar affinities for tracer quantities of calcium. However, the affinity of PP-L from both zones of scapular cartilage for tracer quantities of calcium was greater than that of PP-L from nasal septum. The data obtained from this study do not indicate sufficient differences between the chemical composition and calcium affinity of proteinpolysaccharides from resting and ossifying scapular cartilage to account for the calcium uptake in the ossifying zone.This work was supported by the U.S. Atomic Energy Commission and by U.S. Public Health Service Special Fellowship (QTS), 1-F3-GM-16, 179–01.