尖吻蝮蛇毒抗凝血因子Ⅱ与活化凝血因子Ⅹ的结合性质

The Binding of the Anticoagulation Factor Ⅱ from the Venom of Agkistrodon acutus with Activated Factor Ⅹ.

皖南尖吻蝮蛇毒抗凝血因子Ⅱ (ACFⅡ )与活化凝血因子Ⅹ (FⅩa)在钙离子作用下形成了 1∶1的复合物 ,从而延长凝血时间 .这个复合反应是依赖于钙离子的 ,ACFⅡ在没有钙离子存在条件下不能与FⅩa形成复合物 .ACFⅡ是凝血因子Ⅸ或凝血因子Ⅹ结合蛋白家族中一个新发现的成员 ,其相对分子质量为 2 946 8 1.ACFⅡ分子中含有 2 5 1个氨基酸残基 ,其氨基酸组成与这一家族中其他成员十分相似 .ACFⅡ在抗凝血反应中存在一临界浓度 (12nmol/L) ,只有在高于其临界浓度时 。

Anticoagulation factor Ⅱ (ACFⅡ) from the venom of Agkistrodon acutus forms a 1∶1 complex with activated coagulation factor Ⅹ (FⅩa) in the presence of Ca 2+ ions. The result that ACFⅡ fails to form a complex with FⅩa in the absence of Ca 2+ ions indicates that the binding is in the Ca 2+ dependent manner. ACFⅡ is a new member of the Ⅸ/Ⅹ bp family, and has a similar amino acid composition to the other members of this family. It is composed of 251 amino acid residues with a relative molecular mass of 29 468 1, determined by MALDI TOF MS. ACFⅡ prolongs plasma prothrombin time (PPT) in the dose dependent fashion and exhibits marked anticoagulant activity only at the concentration higher than the critical concentration (12 nmol/L) of ACFⅡ.