Comparison of carbohydrate-containing substances from non-calcified and calcified portions of bovine costal cartilage.

Carbohydrate-containing substances were extracted from non-calcified (NCC) and calcified (CC) portions of bovine costal cartilage with 0.5 M LaCl3 by the method of Mason and his co-workers, followed by dilution of the extract with 9 volumes of water. The precipitate formed on dilution yielded Fr. P, while Fr. S was obtained from the supernatant. Fr. P was separated into two subfractions by gel filtration on Sepharose 2B. The experimental results showed that Fr. P contained proteoglycans with different molecular sizes and compositions, while Fr. S contained proteoglycan, hyaluronic acid, glycoproteins, and glycogen. The present data suggest that in the proteoglycan of Fr. P, the relative content of chondroitin sulfate decreases with a concomitant increment in that of keratan sulfate on calcification. In addition, elevation of the ratio of chondroitin 4-sulfate to chondroitin 6-sulfate, together with a small increment of non-sulfated disaccharide units in the chondroitin sulfate chains appear to occur on calcification. The glycogen content in Fr. S diminished on calcification. The present observations suggest therefore that the remodeling of proteoglycan consumption of glycogen in bovine costal cartilage occur on calcification.