The Conversion of Prothrombin in the Intrinsic System*

Abstract

SummaryA method is described for formation and partial isolation of intrinsic activator (I.A.). The term intrinsic activator of prothrombin conversion is used instead of blood thromboplastin to avoid ambiguity.The reaction of a purified prothrombin, I.A. and calcium in the thrombin formation is studied in different experiments. The following results are given as conclusion :A determinated amount of calcium is necessary for the full activity of the intrinsic activator. Calcium is probably fixed to the I.A. A too high concentration of calcium produces inhibition.The I.A. behaves as an enzyme in prothrombin conversion, prothrombin as a substrate.