EFFECT OF BLOOD THROMBOKINASE, AS INFLUENCED BY SOY BEAN TRYPSIN INHIBITOR; ULTRACENTRIFUGATION, AND ACCESSORY FACTORS

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Abstract
Blood thrombokinase, prepared from bovine plasma globulin by adsorption on BaSO4, is a heat-labile, non-dialyzable factor, associated with proteins soluble in 0.35, but precipitable by 0.45 saturated NH4HSO4 at pH 5.25. It can activate prothrombin without the aid of ionic C, without cephalin, without platelets, and without material completely sedimentable in 120 minutes at 85,000 g. Almost all the activity remained in the supernate when thrombokinase was centrifuged for 120 minutes at 85,000 g crystallized soy bean trypsin inhibitor suppressed activation of prothrombin by thrombokinase. Effectiveness of thrombokinase was multiplied a hundredfold or more when complemented by C, cephalin, and "accelerator." Cephalin and "accelerator" were ineffective without ionic C. C, cephalin, and "accelerator," together, failed to activate prothrombin without thrombokinase. It is not certain whether the "accelerator" functioned as an accessory factor, as a potential source of more thrombokinase, or both. Activation of prothrombin by thrombokinase is the basic reaction, upon which the effects of C, cephalin, and "accelerator" are superimposed.