Plasminogen-Plasmin System: III. Kinetics of Plasminogen Activation and Inhibition of Plasminogen-Plasmin System by some Synthetic Inhibitors*

Abstract

1. The effects of synthetic inhibitors on the activation of plas-minogen by streptokinase and on the esterolytic, caseinolytic and fibrino-lytic activities of plasmin [EC 3.4.4.14] were investigated. The inhibitors examined are ɛ-aminocaproic acid, trans-4-aminomethylcyclohexane-carboxylic acid, cis-4-aminomethylcyclohexanecarboxylic acid and the corresponding n-hexyl ester derivatives. 2. All of these inhibitors acted as the competitive type of inhibitor on the plasminogen activation, and the n-hexyl esters were more potent than the parent acids. 3. The acids were weak non-competitive inhibitors of the esterase activity of plasmin, while the hexyl esters were competitive inhibitors. Anti-caseinolytic effects of these synthetic inhibitors were similar to their anti-esterolytic effects. In fibrinolytic system, however, inhibitory effects of the acids were comparable with those of the esters. 4. Stereospecificity was observed in inhibitory effects of the stereo-isomers of 4-aminomethylcyclohexanecarboxylic acid and its n-hexyl ester derivatives.