Partial purification of intermediate coagulation product I and a study of its properties

¹ Department of Hematology, Laboratory Division, Montefiore Hospital, New York City

Intermediate coagulation product I, a precursor of "blood thromboplastin," has been isolated and partially purified by starch-block electrophoresis. The electrophoretic procedure eliminated thrombin, fibrinolytic and esterase activity, phospholipids, and an unidentified inhibitor of product I which appears to be present in serum. Partial purification markedly increased the heat and storage stability of the compound. Product I has been shown to convert purified prothrombin to thrombin in the presence of factor V and phospholipids. Its activity is not inhibited by diisopropyl fluorophosphate. The compound is antigenic and its activity can be inhibited by specific antibody which considerably lengthens the clotting time of substrate plasma. Purified product I failed to induce viscous metamorphosis of platelets. This activity in the crude preparations was shown to result from contaminating thrombin.