The Role of Proaccelerin in Human Blood Coagulation. Evidence that Proaccelerin Is Converted to a Prothrombin-converting Principle by Activated Stuart Factor: With Notes on the Anticoagulant Action of Soybean Trypsin Inhibitor, Protamine Sulfate, and Hexadimethrine Bromide*

In his original description of a patient with parahemophilia and his studies on the nature of the defect, Owren (1) proposed that the missing factor, proaccelerin (Factor V), was converted, in the presence of calcium, into a prothrombin- converting substance ("prothrombinase," Factor VI) by the action of tissue thromboplastin. Other investigators, notably Ware and Seegers