The Activation of Proaccelerin by Bovine Thrombokinase (with Notes on the Antithrombic Activity of Phenylmethyl Sulfonylfluoride)

view.24 One explanation for the differences obtained with human and bovine materials is that preparations of the different clotting factors are not equally deficient in contaminating substances. The present experiments examine the interaction between activated bovine Stuart factor and bovine proaccelerin under conditions minimizing the influence of contaminating substances. Milstone has purified a clot-promoting agent from bovine plasma to which he has given the name of “plasma thrombokinase.”5 In the studies reported now, bovine plasma thrombokinase, treated to reduce its contamination by thrombin, appeared to activate bovine proaccelerin in an enzymatic manner. Bovine plasma thrombokinase corrects the abnormality in plasma deficient in Stuart factor,1-” and seems to be similar in behavior to human activated Stuart factor. Under these conditions, then, the activation of proaccelerin by activated Stuart factor appeared to he similar in bovine and human systems.