Guillin M C, Bezeaud A
Ann Biol Clin (Paris). 1987;45(2):184-90.
Protein C is a potent inhibitor of blood coagulation, and, in addition, appears to be a profibrinolytic agent. In a first step, protein C must be converted to a serine protease. This activation is catalyzed by a complex formed between thrombin and thrombomodulin, an endothelial cell surface protein. Activated protein C exhibits its anticoagulant activity through the proteolytic inactivation of two blood coagulation cofactors, factors Va and VIIIa. This reaction requires phospholipids, originating from platelets or endothelial cells, and a cofactor protein, protein S. Protein S enhances the binding of activated protein C to phospholipids. In addition, activated protein C stimulates fibrinolysis, through the inactivation of the tissue plasminogen activator (tPA) inhibitor. An isolated constitutional, quantitative or qualitative, protein C or protein S deficiency increases the risk of thrombosis, the clinical features are different in the rare cases of homozygous protein C deficiency (neonatal purpura fulminans) or in the heterozygous patients (recurrent venous thrombosis in young adults). Acquired deficiency in protein C and S had been observed in liver disease, during vitamin K antagonists or L-Asparaginase treatment, and in disseminated intravascular coagulation.
蛋白C是一种强效的血液凝固抑制剂，此外，它似乎还是一种促纤溶因子。第一步，蛋白C必须转化为丝氨酸蛋白酶。这种激活由凝血酶与血栓调节蛋白（一种内皮细胞表面蛋白）形成的复合物催化。活化蛋白C通过对两种血液凝固辅因子（因子Va和VIIIa）进行蛋白水解失活来发挥其抗凝活性。该反应需要源自血小板或内皮细胞的磷脂以及一种辅因子蛋白——蛋白S。蛋白S可增强活化蛋白C与磷脂的结合。此外，活化蛋白C通过使组织型纤溶酶原激活物（tPA）抑制剂失活来刺激纤溶。孤立的先天性、定量或定性的蛋白C或蛋白S缺乏会增加血栓形成的风险，在罕见的纯合子蛋白C缺乏病例（新生儿暴发性紫癜）或杂合子患者（年轻成年人复发性静脉血栓形成）中，临床特征有所不同。在肝病、维生素K拮抗剂或L-天冬酰胺酶治疗期间以及在弥散性血管内凝血中，已观察到获得性蛋白C和S缺乏。
