DESCRIPTION OF 2 CLASSES OF PROTEINASES FROM ENAMEL EXTRACELLULAR-MATRIX CLEAVING A RECOMBINANT AMELOGENIN

This paper is a short review of our recent studies on amelogenin prote olysis in vitro using a recombinant mouse amelogenin M179 as a substra te, The specific aims of this study were to identify, isolate and char acterize the proteinases in the enamel extracellular matrix, We identi fied two classes of enamel proteinases; 1) the high molecular weight p roteinase (60-68 kDa) cleaves the c-terminal segment of M179 and is a calcium dependent metalloproteinase with an optimum pH of 8.2) The low molecular weight proteinase (similar to 30 kDa) removes the TRAP (Tyr osine Rich Amelogenin Polypeptide) sequence and causes further degrada tion of M179, The latter was identified to be a serine proteinase with an optimal activity at pH 6, These data support the notion that ename l proteinases cleave amelogenin through specific and highly controlled mechanisms and that they mag fulfill direct roles during enamel matur ation.