Purification of mouse sperm acrosin, its activation from proacrosin and effect on homologous egg investments.

When proacrosin from mouse epididymal spermatozoa was activated a single form of acrosin was produced. The enzyme was isolated by gel filtration followed by affinity chromatography using Sepharose-4B linked to an acrosin inhibitor p-(p'-aminophenoxypropoxy)benzamidine. The molecular weight of partly purified acrosin was 53 000 by gel filtration, and of the pure enzyme 39 000 by SDS-polyacrylamide gel electrophoresis. Pure mouse acrosin removed the cumulus oophorus, corona radiata and zona pellucida from the homologous egg. It is proposed that penetration of spermatozoa through egg investments, particularly through the zona pellucida, is a simpler process in the mouse than in the sheep.