PZ-peptidase activity from ejaculated boar spermatozoa

Protein constituents of the boar spermatozoon were fractionated in three components, the hypotonic soluble fraction, the detergent-soluble fraction, and the detergent-insoluble fraction. When all these fractions were assayed spectrophotometrically using the PZ-peptide as substrate, a high value of PZ-peptidase specific activity was observed in the first fraction. Electrophoretic analysis at pH 8.3 of the protein content from the hypotonic soluble fraction revealed the existence of multiple molecular forms capable of hydrolysing the PZ-peptide. The major form was characterized by a surprisingly high value of electrophoretic mobility, index of the presence of numerous negatively charged residues. Biochemical and ultrastructural analyses showed that the hypotonic soluble fraction did not contain intrinsic, and specifically acrosomal, sperm enzymes.