Inhibition of acrosin by benzamidines

Acrosin proved to be very susceptible to inhibition by benzamidine derivatives. Most of the inhibitors were at least 10-fold more potent against acrosin than against trypsin. The most potent inhibitors of acrosin of this series were amidinophenyl compounds with a keto group or a carbon amide moiety in the side chain. Comparison of the structure-activity relationships for the inhibition of acrosin and trypsin showed differences in the binding sites of both enzymes.