Neonatal hamster molar tooth development: extraction and characterization of amelogenins, enamelins, and soluble dentin proteins

Abstract

Amelogenins, enamelins, and soluble dentin proteins were sequentially separated under dissociative conditions from morphologically characterized molar tooth germs of 4-, 6-, and 7-day-old hamsters. Polyacrylamide gel electrophoretic, gel filtration chromatographic, and amino acid compositional data of neonatal hamster amelogenin extracts were in general agreement with those obtained from fetal bovine enamel under similar extraction conditions. As development progressed (e.g., 4 vs. 7 days of life), changes in amelogenin proteins were manifested by altered values of all biochemical parameters measured. A high molecular weight (approximately 160,000-200,000 daltons) Stains-All-positive protein band was observed for all hamster enamelin extracts on SDS gels. Amino acid compositional data from this "enamel crystal protein," partially purified by dissociative gel-filtration chromatography, are presented. The hamster dentin phosphoprotein was partially purified by ion-exchange chromatography in 7M urea. The molecular weight (75,000-80,000 daltons) and amino acid composition of this protein were similar to those of rat incisor dentin phosphoprotein, but different from those of the fetal bovine phosphoprotein.