Activities Associated with Thrombokinase Derived from Bovine Plasma. ∗

Abstract

Summary

Bovine thrombokinase, incompletely purified, was subjected to gel filtration on Sephadex G-200. Almost all of the protein emerged from the column in the position corresponding to the third wave of serum proteins. The thrombokinase subfractions had the capacity to activate prothrombin in the presence of oxalate, to cause prothrombin activation in a system containing calcium, phospholipid and accelerator (factor V), and to activate chymotrypsinogen. No separation of these activities was evident. This makes it desirable to enquire further whether these activities, as well as the TAMe esterase and the power to correct the Stuart defect, are all properties of the thrombokinase molecule. Accumulating evidence continues to favor the view that thrombokinase can, under proper circumstances, activate prothrombin without the help of presently known forms of accelerator (factor V).