Urinary procoagulant behaves as tissue factor by promoting factor VIIa-catalyzed activation of factor X

We purified the urinary procoagulant from frozen human urine by introducing phenyl-Sepharose hydrophobic chromatography. By this method, the apoprotein of the procoagulant and the lipid-like substance were separately recovered. Upon reassociation with the lipid-like substance or exogenous crude phospholipids, the apoprotein accelerated factor VIIa-catalyzed activation of factor X, probably by forming a stoichiometric complex with the catalytic enzyme. Thus the procoagulant was confirmed to be a tissue factor by its mode of participation in the blood coagulation mechanism.