Proteoglycans of dentine and predentine.

A density gradient system is presented by which dentine and predentine are separated, leaving an intermediate fraction, which contains material from the mineralization front. From the fractions thus obtained the proteoglycans were extracted with 4 M guanidinium chloride and further purified in urea on a DEAE column. The glycosaminoglycans extracted from dentine appeared to be protein-bound, as judged from papain digestion experiments. The polydispersity of dentine proteoglycans seemed to depend, at least partly, upon the polydispersity of its glycosaminoglycans. The materials extracted from the three tissue fractions were ellted in a similar way from Sepharose 6 B, and the amino acid composition of the preparation was determined. The differing proteoglycan patterns of the three tissue fractions indicate a metabolism related to the mineralization front.