Stabilization of the E* Form Turns Thrombin into an Anticoagulant
Stabilization of the E* Form Turns Thrombin into an Anticoagulant
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DOI：
10.1074/jbc.m109.012344
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发表时间：
2009-07-24
影响因子：
4.8
通讯作者：
Di Cera, Enrico
中科院分区：
文献类型：
--
作者：
Bah, Alaji;Carrell, Christopher J.;Di Cera, Enrico
先前的研究表明，在凝血酶自溶环中缺失9个残基会产生具有潜在临床相关性的抗凝倾向的突变体，但该效应的分子起源仍未得到解决。以1.55埃分辨率以自由形式解析的该突变体的X射线晶体结构揭示了与最近鉴定的E* 形式几乎相同（均方根偏差为0.154埃）的非活性构象。Trp（215）的侧链通过从其在活性E形式中的位置移动> 10埃而塌陷到活性位点中，并且氧阴离子空穴通过Glu（192）-Gly（193）肽键的翻转而被破坏。这一发现证实了存在与凝血酶突变体D102 N结构中首次鉴定的基本相同的无活性形式E*。此外，它还表明，通常由凝血酶支架突变引起的抗凝剂特性可能源于无活性E* 形式的稳定化，在血栓调节蛋白和蛋白C结合后，无活性E* 形式选择性地转变为活性E形式。
Previous studies have shown that deletion of nine residues in the autolysis loop of thrombin produces a mutant with an anticoagulant propensity of potential clinical relevance, but the molecular origin of the effect has remained unresolved. The x-ray crystal structure of this mutant solved in the free form at 1.55 angstrom resolution reveals an inactive conformation that is practically identical (root mean square deviation of 0.154 angstrom) to the recently identified E* form. The side chain of Trp(215) collapses into the active site by shifting > 10 angstrom from its position in the active E form, and the oxyanion hole is disrupted by a flip of the Glu(192)-Gly(193) peptide bond. This finding confirms the existence of the inactive form E* in essentially the same incarnation as first identified in the structure of the thrombin mutant D102N. In addition, it demonstrates that the anticoagulant profile often caused by a mutation of the thrombin scaffold finds its likely molecular origin in the stabilization of the inactive E* form that is selectively shifted to the active E form upon thrombomodulin and protein C binding.