Non-collagenous proteins of predentine from dentinogenically active bovine teeth

Abstract

Predentine(e) was dissected out from unerupted permanent bovine teeth. The noncollagenous proteins were extracted at -13.degree. C by 4 M-guanidinium chloride containing proteinase inhibitors and separated by DEAE-Sepharose and Sephadex G-100 chromatography. In addition to a few minor constituents, the only major noncollagenous components that could be demonstrated were albumin and proteoglycan. The localization of the former, demonstrated by optical-microscopical immunochemistry, was such that it was concluded that albumin is not a constituent of predentin matrix. Very low amounts of phosphoprotein were found in predentin matrix. This was of 2 types, high- and low-phosphorylated. Larger amounts of phosphoprotein were not present until the dissection was carried deeper into newly formed dentin(e). On the basis of the present results and previously obtained morphological data the conclusion was drawn that predentin matrix, containing virtually only collagen type I and proteoglycan, is similar in composition to that of loose connective tissue and primarily aimed at the production and maturation of collagen fibers. Only immediately before the mineralization front are the noncollagenous protein components secreted that initiate and govern Ca-phosphate mineral formation.