Extraction of cartilage protein–polysaccharides with inorganic salt solutions

Abstract

1. Bovine nasal cartilage was extracted with inorganic salt solutions of various ionic strengths. The efficiency of extraction of protein–polysaccharide from the tissue was determined for each extraction. The results confirm and enlarge earlier observations (Sajdera & Hascall, 1969). 2. The chloride salts of lanthanide metals extract high yields of protein–polysaccharide from the tissue at much lower concentrations than was achieved with univalent and bivalent salts. 3. The lanthanum salt of extracted protein–polysaccharide precipitates when the concentration of LaCl3 is decreased. Precipitation is complete in the presence of 0.05m-LaCl3. This finding is relevant to the interpretation of earlier observations on the effect of LaCl3 on elastic recovery of articular cartilage after compression (Sokoloff, 1963). 4. A linear relationship was found between the concentration at which a particular salt is maximally effective in solubilizing protein–polysaccharide from the tissue and the enthalpy of hydration of the cation of the salt. On the basis of this relationship a hypothesis is proposed to explain the characteristic protein–polysaccharide-extraction profiles exhibited by inorganic salt solutions.