PURIFICATION AND CHARACTERIZATION OF A VARIANT OF HUMAN PROTHROMBIN -PROTHROMBIN SEGOVIA

A dysprothrombin designated prothrombin Segovia was isolated from the plasma of an individual with normal prothrombin antigen and prothrombi n activity lesser than 25% of the control prothrombin activity. Activa tion by prothrombinase complex showed a lower amidolytic than clotting activity, which suggests a lesser generation of active intermediates than normal prothrombin. When prothrombin Segovia was activated by pro thrombinase complex in the absence of factor Va, no thrombin formation was found by functional activities. SDS-PAGE analysis of the molecule s derived by activation with prothrombinase complex, Taipan snake veno m and Echis carinatus venom showed an accumulation of molecules not cl eaved at bond Arg320-Ile321. This was more evident with Echis carinatu s venom which only acts on this bond. Our data suggest that the altera tion of prothrombin Segovia impairs the scission of bond Arg320-Ile321 . (C) 1997 Elsevier Science Ltd.