Characterization of Basic Proteins of Bull Seminal Plasma

Abstract

High-performance liquid chromatography on reversed phase columns was used to analyze the major basic proteins from bull seminal plasma. The proteins were separated preparatively and characterized with respect to molecular mass, amino-acid composition as well as by means of immunodiffusion against specific antisera. The following proteins could be identified: bull seminal proteinase inhibitor II (BUSI II), 2 seminal RNases, the seminal antimicrobial protein and proteolytic fragments, derived from it, and a hitherto unknown protein P6 of molecular mass 20,000 Da [daltons]. Another unknown protein, P5, formed during preparation of the basic protein fraction turned out to be a proteolytic fragment of protein P6 with a molecular mass of 8750 Da for the polypeptide chain. Antisera against the isolated proteins were raised in rabbits and their specificity established. Single radial immunodiffusion was used to determine the concentration of the above basic proteins in bull seminal plasma: BUSI II (0.25 mg/ml), seminal RNases (6.5 mg/ml) and protein P6 (2.9 mg/ml).