Nonamelogenin components of porcine enamel in the protein fraction free from the enamel crystals

Abstract

The enamel protein fraction free from enamel crystals was investigated to determine the existance of nonamelogenin like enamelin. Enamel proteins were extracted by neutral and alkaline buffers from the porcine immature enamel at an early stage of development and resolved into four fractions on Sephadex G-100 gel filtration in a carbonate buffer (pH 10.8). The first eluted fraction contained the aggregate of proteins from 13,000 daltons to 142,000 daltons in molecular size and most of these proteins were found to differ from amelogenin by their different solubility against 25% isopropanol on acrylamide gel, and their amino acid composition. These nonamelogenins showed the property of closely associating with synthetic hydroxyapatite under dissociative conditions, and their electrophoretic properties and amino acid compositions were quite similar to those of the enamelins prepared from porcine immature enamel.