Abstract
A density fractionation procedure has been used to study the characteristic proteoglycans of bovine alveolar bone at different degrees of mineralization. Bone powder fractions were extracted with 4 M guanidium chloride (GdmCl) and subsequently demineralized with 0.5 M ethylenediamine tetraacetic acid (EDTA) containing protease inhibitors. Alveolar bone powder was distributed into density fractions from 1.8 to 2.1 g/cm3. The amount of non-collagenous proteins markedly decreased with increasing density. Hexuronic acid content was also decreased with increasing density. Chromatographic analysis of the proteoglycans indicated three species of proteoglycans in these extracts. A large proteoglycan, present only in GdmCl extract (corresponds to non-mineralized region), diminished with increasing density. A relatively small proteoglycan was present in both GdmCl and EDTA extract (mineralized region). The amino acid composition and immuno reactivity of each small proteoglycan was similar. Yet, all three proteoglycans were cross-reactive with anti-small proteoglycan. These data suggest that the decrease of proteoglycan and the change of its size is related to the mineralization process in bone.
