Involement of an acrosinlike proteinase in the sulfhydryl-induced degradation of rabbit sperm nuclear protamine

Open Access
Publisher Website
Google Scholar
Abstract
Proteolytic activity is associated with isolated rabbit sperm nuclei and is responsible for the degradation of nuclear protamine that occurs during thiol-induced in vitro decondensation of the nuclei. Results of experiments designed to characterize this proteolytic activity are presented. Basic protein isolated from rabbit sperm nuclei incubated with 5 mM dithiothreitol (DTT) and 1% Triton X-100 for increasing periods of time exhibited progressively faster migrating bands on acid-urea polyacrylamide gels, reflecting the progressive degradation of protamine. Ultimately, a specific and characteristic peptide banding pattern resulted. When sperm nuclei were treated with the esterase inhibitor nitrophenyl-p-guanidino benzoate to inhibt the nuclear-associated proteolytic activity and then incubated with 1 of several exogenous proteinases and DTT and Triton X-100, characteristic peptide banding patterns were seen for each exogenous proteinase employed. For trypsin, chymotrypsin, pronase and papain, the peptide banding patterns differed from one another and from the pattern characteristic of protamine degradation by the nuclear-associated proteinase. When rabbit acrosin served as the exogenous proteinase, the peptide banding pattern seen was identical to the pattern characteristic of the nuclear-associated proteinase. The proteinase associated with rabbit sperm nuclei and involved in sperm nuclear decondensation in vitro is evidently acrosin-like.