Synthetic inhibitors of serine proteinases. 22. Inhibition of acrosin by benzamidine derivatives.

A series of substituted benzamidines was tested for their inhibitory effects on boar acrosin. Substituents with electron-donating properties and small aliphatic residues increase the inhibitory activity of benzamidine, whereas aromatic residues have only a slight enhancing influence. Only substituents with a beta- or gamma-keto group increase the acrosin binding affinity by more than one order of magnitude. Comparison of the structure-activity relationships for the inhibition of acrosin and trypsin showed differences in the binding sites of both enzymes.