Activation of plasminogen by trypsin and plasmin.

teolytic enzyme plasmin (fibrinolysin) is supposed to be present in normal blood plasma in an inactive form, called plasminogen (proplasmin). Anxiety, strenuous exercise, hemorrhage, burn , t rauma (‘ ‘tourniquet shock’ ‘) and epinephrine admmistration have heels found to produce increased fibrinolytic activity (plasmin formation) in the blood. 3 The physiologic mechanism of activation of proplasmin in the normal organism is at present unknown. Since plasmin is al)le to digest fibrinogen and prothrombin,2 and to lyse fibrin clots, its presence in blood may lead to fatal failure of the hemostatic mechanism. Human plasminogen may be converted to plasmin by treatment with chloroform4 or with streptokinase5 or staphylokinase.6 Bovine plasminogen, however, is apparently resistant to the action of these kinases and the only known w’ay to bring about conversion to the active enzyme is by treatment with chloroform. However, it is apparent that none of the above mentioned activators can he