de Fouw N J, Haverkate F, Bertina R M, Koopman J, van Wijngaarden A, van Hinsbergh V W
Blood. 1986 Apr;67(4):1189-92.
The effect of purified human activated protein C (APC) and protein S on fibrinolysis was studied by using an in vitro blood clot lysis technique. Blood clots were formed from citrated blood (supplemented with 125I-fibrinogen) by adding thrombin and Ca2+-ions; lysis of the clots was achieved by adding tissue-type plasminogen activator. The release of labeled fibrin degradation products from the clots into the supernatant was followed in time. We clearly demonstrated that APC accelerates whole blood clot lysis in vitro. The effect of APC was completely quenched by antiprotein C IgG, pretreatment of APC with diisopropylfluorophosphate, and preincubation of the blood with antiprotein S IgG. This demonstrates that both the active site of APC and the presence of the cofactor, protein S, are essential for the expression of the profibrinolytic properties. At present, the substrate of APC involved in the regulation of fibrinolysis is not yet known. Analysis of the radiolabeled fibrin degradation products demonstrated that APC had no effect on the fibrin cross-linking capacity of factor XIII.
采用体外血凝块溶解技术研究了纯化的人活化蛋白C（APC）和蛋白S对纤维蛋白溶解的影响。通过添加凝血酶和钙离子，由枸橼酸盐血（补充有125I-纤维蛋白原）形成血凝块；通过添加组织型纤溶酶原激活剂实现血凝块的溶解。随时间监测标记的纤维蛋白降解产物从血凝块释放到上清液中的情况。我们清楚地证明，APC在体外可加速全血凝块溶解。抗蛋白C IgG、用二异丙基氟磷酸对APC进行预处理以及用抗蛋白S IgG对血液进行预孵育可完全消除APC的作用。这表明APC的活性位点和辅因子蛋白S的存在对于纤溶特性的表达都是必不可少的。目前，参与纤维蛋白溶解调节的APC底物尚不清楚。对放射性标记的纤维蛋白降解产物的分析表明，APC对因子XIII的纤维蛋白交联能力没有影响。
