Human Acrosin: Purification and Some Properties

Abstract

Human sperm with normal morphology and good viability were obtained by centrifugation using a discontinuous Percoll density gradient with an inner column. Acrosin (E.C. 3.4.21.10) was rapidly purified from sperm by ion exchange adsorption and elution and was purified by affinity adsorption on a lima bean trypsin inhibitor (LBTI) Cellulofine column. The final preparation was found to be homogeneous on polyacrylamide gel electrophoresis and to have a molecular weight of about 4 × 104 daltons. The enzyme had an esterolytic activity of 3.5 μmol/min/A₂₈₀ with N-a-tosyl-L-arginine methyl ester as the substrate. Human acrosin showed a broad substrate specificity for arginine and lysine derivatives and it seemed to have a somewhat different specificity from trypsin. The optimal pH of this enzyme with amidolytic activity was 9.0. Enzyme activity was stimulated by a high concentration of calcium chloride. LBTI and aprotinin strongly suppressed the amidolytic activity with the D-valyl-L-leucyl-L-arginine-p-nitroanilide (Val-Leu-Arg-pNA) as the substrate, but α₁ -antitrypsin and soybean trypsin inhibitor were less effective.

Key Words:

• Acrosin
• Human seminal plasma
• Purification
• Affinity chromatography
• Substrate specificity
• Arginine esterase.