Enzyme compartmentalization during biphasic enamel matrix processing

Processing of enamel matrix proteins is essentially biphasic, Secretory sta ge metalloprotease activity generates a discrete, presumably functional, sp ectrum of molecules which may also undergo dephosphorylation, Maturation st age serine proteases almost completely destroy the matrix. The present aim was to examine the tissue compartmentalization of these enzyme activities i n relation to their possible function, A sequential extraction using synthe tic enamel fluid, phosphate buffer and SDS was used to identify enzymes fre e in the enamel fluid, crystal bound or aggregated with the bulk matrix res pectively. Results indicated that the metallo-proteases and alkaline phosph atase were free in the secretory stage enamel fluid while the serine protea ses appeared to be largely bound to the maturation stage crystals, The mobi lity of the metallo-proteases and alkaline phosphatase would ensure efficie nt initial processing of secretory matrix, while the largely mineral bound serine proteases would ensure retention of protease activity despite massiv e destruction and protein removal.