ENAMELINS IN THE NEWLY FORMED BOVINE ENAMEL

The possibility of using the antisera raised in rabbits against the po rcine 25 kDa amelogenin, 32 and 89 kDa enamelins, and the 13-17 kDa no namelogenin for the differentiation and identification of the protein components in bovine immature enamel was examined. Although the immuno reactivities of these antisera against bovine enamel proteins were wea ker than those against the porcine proteins, it was found that these a ntisera could differentiate and demonstrate immunohistochemically a ch aracteristic distribution of three different kinds of enamel protein c omponents in the bovine secretory stage enamel similar to those observ ed in the porcine immature enamel. Of the several high molecular weigh t proteins being reactive to the anti-porcine 32 and 89 kDa enamelin s era, the 130 kDa protein, having the highest molecular weight, was ext racted and purified from the bovine enamel sample which was obtained b y peeling approximately 30-mum thickness of the outermost layer of the secretory stage enamel. The amino acid composition of the 130 kDa pro tein was similar to the known bovine enamelins, and was rich in aspart ic acid, glutamic acid, proline, and glycine. The results could sugges t that the enamelins of lower molecular weight than this protein, whic h are found in the bovine secretory stage enamel, are derived from thi s precursor protein.