Abstract

PIP: The observation of 2 proacrosins in extracts of human spermatozoa is described. When spermatozoa were extracted in the presence of .05 M benzamidine the resulting solutions reveled a time-dependent, sigmoidal increase of trypsinlike activity upon incubation at pH 8. Gel permeation chromatography of those extracts separated 2 species, P1 and P2, with apparent molecular weights of 75000 and 42000, respectively. Both species are autoactivatable at pH 7-8 and the kinetic parameters of activated P1 and P2 are indistinguishable from those of human acrosin. That both are inactive precursors of human acrosin is shown by the fact that in the presence of benzamidine they are obtained instead of and in greater yield than acrosin. The features of the activation process show that P1 and P2 are zymogens.