In vitro prothrombin synthesis from a purified precursor protein: II. Partial pirification of bovine carboxylase

The isolation and partial purification of an enzyme system that converts bovine decarboxyfactor II (PIVKA-II) into prothrombin (factor II) is described. The increase in factor II activity occurs in parallel with 14CO2 incorporation into BaSO4 adsorbable proteins. The system is not strictly vitamin K-dependent because it is obtained from the livers of normal healthy cows. By preincubating the enzyme(s) with an excess of warfarin, an absolute vitamin K1-dependence can be obtained. The reaction is inhibited by its own product, factor II.