Acid extraction of acrosin from human spermatozoa pretreated by different physicochemical methods

Washed human spermatozoa were subjected to different physicochemical methods, followed by acid extraction of the sperm acrosomes to dissolve acrosin. The acrosin activity of the sperm pellet and the supernatant was determined by benzoyl arginine ethyl ester/alcohol dehydrogenase (BAEE/ADH) assay to calculate the total acrosin activity in mU/10(6) spermatozoa. Membrane-active and zymogen-activating agents increased the total acrosin activity 50%-200% compared to acid extraction alone. Similar results were obtained by osmotic shock, sonication and treatment with glass beads. Snap freezing of unprotected spermatozoa in liquid nitrogen yielded a fivefold increase in total acrosin activity, thus demonstrating that this is the method of choice for optimal acrosin extraction. The possibility is discussed as to whether acrosomal membrane alterations with improved solubilization of membrane-bound acrosin and/or conformational changes and/or zymogen activation are responsible for the considerable increase observed in acrosin activity.