Meizothrombin formation during factor Xa-catalyzed prothrombin activation. Formation in a purified system and in plasma.

摘要: Meizothrombin and thrombin formation were quantitated during factor Xa-catalyzed activation of human prothrombin in reaction systems containing purified proteins plasma. In the system considerable amounts meizothrombin accumulated when was activated by Xa (with or without accessory components) under initial steady state conditions. The ratio rates not influenced variation pH, temperature, ionic strength medium. When 2 microM complete prothrombinase complex (factor Xa, Va, Ca2+, phospholipid) 80-90% initially formed product meizothrombin. Lowering concentration from to 0.03 caused a gradual decrease meizothrombin/thrombin 5 0.6. phosphatidylserine content phospholipid vesicles varied between 20 1 mol % analyzed at relative amount decreased 85 55%. With platelets, cephalin, thromboplastin as procoagulant lipid, major only 30-40% We also time courses both with substantial wide variety experimental However, little no detected plasma which coagulation initiated via extrinsic pathway intrinsic kaolin plus (cephalin, phosphatidylserine-containing vesicles). Thus, active that ex vivo experiments