Boar Acrosin

Acrosin is a proteolytic enzyme used by sperm to digest a path through the zona pellucida of the ovum.In ejaculated sperm it is inactivated by a proteinase inhibitor from seminal plasma that also inhibits trypsin.This inhibitor is removed or inactivated during the residence in the female reproductive tract as a part of the capacitation process.The boar acrosin-inhibitor complex was partially purified using DEAE-cellulose chromatography.The complex was dissociated and the acrosin obtained in a highly purtied form by the use of Sephadex gel filtration at pH 3.0.The final preparations were judged to be homogeneous on the basis of chromatographic and electrophoretic criteria and showed a molecular weight of 30,000.Acrosin has a temperature optimum of 53", an esterase optimum at pH 8.5, and a proteolytic optimum on azocasein at pH 8.7.The enzyme is quite stable at pH 3.0 but undergoes destruction at slightly alkaline pH.Purified acrosin is both activated and stabilized by calcium ions; however, it is not stable to freezing nor to freeze-drying and is inactivated by urea.