...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Proteolysis of blood coagulation factor VIII by the factor VIIa-tissue factor complex: generation of an inactive factor VIII cofactor.
【24h】

Proteolysis of blood coagulation factor VIII by the factor VIIa-tissue factor complex: generation of an inactive factor VIII cofactor.

机译：凝血因子VIIIa-组织因子复合物对凝血因子VIII的蛋白水解：失活的凝血因子VIII辅助因子的产生。

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Activation of factor VIII by thrombin occurs via limited proteolysis at R372, R740, and R1689. The resultant active factor VIIIa molecule consists of three noncovalently associated subunits: A1-a1, A2-a2, and A3-C1-C2 (50, 45, and 73 kDa respectively). Further proteolysis of factor VIIIa at R336 and R562 by activated protein C subsequently inactivates this cofactor. We now find that the factor VIIa-tissue factor complex (VIIa-TF/PL), the trigger of blood coagulation with restricted substrate specificity, can also catalyze limited proteolysis of factor VIII. Proteolysis of factor VIII was observed at 10 sites, producing 2 major fragments (47 and 45 kDa) recognized by an anti-factor VIII A2 domain antibody. Time courses indicated the slow conversion of the large fragment to 45 kDa, followed by further degradation into at least two smaller fragments. N-Terminal sequencing along with time courses of proteolysis indicated that VIIa-TF/PL cleaved factor VIII first at R740, followed by concomitant cleavage at R336 and R372. Although cleavage of the light chain at R1689 was observed, the majority remained uncleaved after 17 h. Consistent with this, only a transient 2-fold increase in factor VIII clotting activity was observed. Thus, heavy chain cleavage of factor VIII by VIIa-TF/PL produces an inactive factor VIII cofactor no longer capable of activation by thrombin. In addition, VIIa-TF/PL was found to inactivate thrombin-activated factor VIII. We hypothesize that these proteolyses may constitute an alternative pathway to regulate coagulation under certain conditions. In addition, the ability of VIIa-TF/PL to cleave factor VIII at 10 sites greatly expands the known protein substrate sequences recognized by this enzyme-cofactor complex.
机译：凝血酶激活因子VIII的过程是通过在R372，R740和R1689进行有限的蛋白水解而发生的。所得的活性因子VIIIa分子由三个非共价缔合的亚基组成：A1-a1，A2-a2和A3-C1-C2（分别为50、45和73 kDa）。随后，活化的蛋白C在R336和R562处进一步对蛋白VIIIa进行蛋白水解，从而使该辅因子失活。现在我们发现，凝血因子VIIa-组织因子复合物（VIIa-TF / PL），具有受限底物特异性的凝血触发物，也可以催化凝血因子VIII的有限蛋白水解。在10个位点观察到了VIII因子的蛋白水解，产生了2个主要片段（47和45 kDa），被抗VIII因子A2域抗体识别。时间进程表明大片段缓慢转化为45 kDa，然后进一步降解为至少两个小片段。 N端测序以及蛋白水解的时间过程表明，VIIa-TF / PL首先在R740处裂解了VIII因子，随后在R336和R372处同时进行了裂解。尽管观察到在R1689处轻链的裂解，但大多数在17小时后仍未裂解。与此相一致，仅观察到因子VIII凝血活性的瞬时增加2倍。因此，VIIa-TF / PL对因子VIII的重链切割产生了不再能够被凝血酶激活的失活的因子VIII辅因子。另外，发现VIIa-TF / PL使凝血酶活化的因子VIII失活。我们假设这些蛋白水解物可能构成在某些条件下调节凝血的另一种途径。此外，VIIa-TF / PL在10个位点切割VIII因子的能力大大扩展了该酶-辅因子复合物识别的已知蛋白质底物序列。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号