Inhibition of serine proteinases by benzamidine derivatives.

Derivatives of benzamidine inhibit competitively the activity of the serine proteinases trypsin, plasmin, thrombin, and of the clotting factor Xa. The inhibitor activities (Ki-values) of various benzamidine derivatives against the several enzymes were compared. Besides parallels, deviations in the corresponding structure-activity relationships were found. From these results it is concluded that the similar enzymes exhibit certain differences in the structure of the primary and secondary binding sites.