Disulfide bonds of basic acrosin inhibitor (BUSI II) from bull seminal plasma

Abstract

The thermolysin digest of the basic acrosin inhibitor (molecular weight 6 200) was resolved on a column of Sephadex G-15 and subsequently by electrophoretic and chromatographic techniques. Cysteine peptides, which link together half-cysteine residues 7 and 39, 17 and 36, and 25 and 57 by disulfide bonds, were isolated. The structure of the molecule of the basic acrosin inhibitor corresponds to structures of inhibitors of the Kazal type. The amino acid sequence of a few residues in the basic acrosin inhibitor has been revised.