On the Purification and Conversion of Human Prothrombin

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Abstract
A combined chemical and immunological method for the purification of human prothrombin is described. After isoelectric precipitation a purified prothrombin is obtained. Its activity per mg of protein is 210 folds higher than that of plasma. This prothrombin and the prothrombin purified on a BaSO4 column are not converted into thrombin in a 25% sodium-citrate solution. No thrombin is formed by the addition of calcium ions and brain thromboplastin. For its conversion, a complete clotting system (extrinsic or intrinsic) is necessary. Our experiments present no evidence for the hypothesis that Factors VII, IX, PPA and Stuart-Prower are prothrombin derivatives. The conversion of prothrombin to thrombin by means of isolated blood thromboplastin is studied. The results still do not permit one to decide whether the reaction is stoichiometric or enzymatic.