Isolation of basic acrosin inhibitor from bull seminal plasma (BUSI II).

An acrosin inhibitor was isolated from bull seminal plasma by gel filtration on Sephadex G-50 fine and ion-exchange chromatography on CM-Sephadex. The inhibitor is a basic polypeptide (pl greater than or equal to 10.5) of molecular weight 6 200 (calculated from amino acid composition). Its N-terminal amino group is blocked. The inhibitor is not strictly specific in its effect since it also inhibits trypsin and to a lesser degree chymotrypsin, in addition to bull and boar acrosin.