凝血酶的结构及其变构特性  

The Structure and Allosteric Character of Thrombin

作　　者：许善峰[1] 李芳[1] 姜涌明[1] 杨生妹[1] 

机构地区：[1]扬州大学生物科学与技术学院,江苏扬州225009

出　　处：《中国医学生物技术应用》2004年第3期18-23,共6页The Chinese Academic Medical Magazine of Organisms

摘　　要：凝血酶(Thrombin,EC3.4.21.5)是一种多功能丝氨酸蛋白水解酶,具有与胰凝乳蛋白酶相似的序列与结构。它含A、B两条多肽链,由一个链间二硫键相连。B链为功能链,具有典型的丝氨酸蛋白水解酶折叠结构,含有1个位于两个β折叠桶之间的活性中心,2个外结合位点(Exosite Ⅰ、Exosite Ⅱ)。1个Na+离子结合位点,一个自我催化水解环(Autolysis Loop)以及一个W60d环(W60dLoop)。凝血酶具有Na+离子诱导的变构酶特性,在血液中有Na+离子结合型和Na+离子解离型两种构象。这两种构象是可以相互转化的。其相互转化的部分机理是由于效应因子或底物结合到凝血酶的特定位点而引起酶构象发生变化和能量转移,从而改变了Na+离子结合与解离的平衡状态。As a member of serine proteases of the chymotryosin family, thrombin(EC3.4.21.5)i8 similar to other enzymes in this family in amino acid residue sequences and structure. It is composed of two polypep-tide chains (A and B)which are covalently linked through a disulfide bond. The B chain carries the functional epitopes of the enzyme and has the typical fold of serir e proteases, with two six-stranded β-barrels of similar structure that pack together asymmetrically to form an active catalytic site at its interface,two ex-osites called Exosite Ⅰ and Exosite Ⅱ , a Na+ binding site, an autolysis loop ,as well as a W60d loop. Throm-bin is a Na+ induced allosteric enzyme which has two forms that can be interconvertible in plasma - the slow (Na+ free) and the fast (Na+ bound) form. The allostery partly owes much to the binding substrate or effector to special epitopes sites of thrombin that induce the conformational change and energy transfer of the enzyme and eventually result in altering the position of the equilibrium between the slow and fast forms.

关 键 词：凝血酶 结构 变构性 变构机理 

分 类 号：Q55[生物学—生物化学]