Properties of acrosomal hyaluronidase from bull spermatozoa. Evidence for its similarity to testicular hyaluronidase.

Sperm acrosomes contain hyaluronidase, the amount varying, respectively, from ram, rabbit, bull, human, boar, rat, and stallion sperm to rooster sperm that do not possess this enzyme. Hyaluronidase was partially purified from bull sperm acrosomal extracts by DEAE-cellulose chromatography. Bull sperm acrosomal hyaluronidase has an optimum pH of 3.75 and is not effected by freezing and thawing or refrigeration, but it is unstable at a pH below 3.0 or temperatures above 50”. The enzyme requires salt for stability and activity and is inhibited by Fe++ and Fe+++ ions or heparin but not by Mn++, Mg++, and Ca++ ions or EDTA. Partially purified acrosomal hyaluronidase from rabbit spermatozoa possesses the same properties. The molecular weight of the hyaluronidase of bull sperm acrosomal extracts was estimated to be 110,000 by gel filtration using a Sephadex G-l 00 column. The acrosomal proteinase-proteinase inhibitor complex appeared as a separate fraction with a molecular weight of 68,000. The activity of bull testicular hyaluronidase as well as bull sperm acrosomal hyaluronidase is inhibited by rabbit immunoantisera prepared against bull testicular hyaluronidase preparations or bull sperm acrosomal extracts. Immunodiffusion experiments showed that bull testicular hyaluronidase and bull sperm acrosomal hyaluronidase preparations have only one component in common. This component was demonstrated to be the hyaluronidase. The results suggest that sperm acrosomal hyaluronidase is identical with testicular hyaluronidase but is apparently ditIerent from lysosomal hyaluronidase, present in organs other than the testis.