[Effect of phosphatidylserine in hemocoagulating action of factors V, VII and autoprothrombin C]

It was found that phosphatidylserine inhibits the activating effect of factors V, VII and autoprothrombin C on the thromboplastin time of plasma. This is in agreement with the previously observed phosphatidylserine ability to form an inactive complex with the substrate of thrombinogenesis, i.e. prothrombin. The excess of autoprothrombin C results in changes in the kinetic parameters of the inhibiting effect of phosphatidylserine on the thrombinogenesis, which is indicative of the interaction between autoprothrombin C and phosphatidylserine. Data from gel-filtration on Sephadex G-100 and differential spectrophotometry support the evidence for the formation of the autoprothrombin C-phosphatidylserine complex. During ion-exchange chromatography and gel-filtration the autoprothrombin C preparations are eluted as an acute symmetrical peak; using electrophoresis in agarose gel, two fractions were revealed in the preparations. The first fraction migrates with gamma-globulins, whereas the second one--with alpha-globulins. The presence of phosphatidylserine in the autoprothrombin C solution does not change its migration rate during electrophoresis.