| Abstract: | Guinea pig sperm contain the exopeptidase dipeptidyl peptidase II (DPP-II). Our purpose was to localize this enzyme in sperm at the ultrastructural level using lysylalanyl-4-methoxy-beta-naphthylamide which is the specific synthetic substrate for DPP-II. In substrate incubated sperm, reaction product was located within the acrosome. It was concentrated over the light staining area which forms the prominent dorsal bulge of the acrosome. Within this area there are spherical zones of moderate electron density which had little or no reaction product. Control sperm did not have reaction product. We conclude that DPP-II is restricted to a compartment within the guinea pig sperm acrosome. |
