Stojanovski Bosko M, Pelc Leslie A, Zuo Xiaobing, Pozzi Nicola, Cera Enrico Di
Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104 USA.
X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Biomol Concepts. 2018 Dec 26;9(1):169-175. doi: 10.1515/bmc-2018-0016.
Meizothrombin is an active intermediate generated during the proteolytic activation of prothrombin to thrombin in the penultimate step of the coagulation cascade. Structurally, meizothrombin differs from thrombin because it retains the auxiliary Gla domain and two kringles. Functionally, meizothrombin shares with thrombin the ability to cleave procoagulant (fibrinogen), prothrombotic (PAR1) and anticoagulant (protein C) substrates, although its specificity toward fibrinogen and PAR1 is less pronounced. In this study we report information on the structural architecture of meizothrombin resolved by SAXS and single molecule FRET as an elongated arrangement of its individual domains. In addition, we show the properties of a meizothrombin construct analogous to the anticoagulant thrombin mutant W215A/E217A currently in Phase I for the treatment of thrombotic complications and stroke. The findings reveal new structural and functional aspects of meizothrombin that advance our understanding of a key intermediate of the prothrombin activation pathway.
中凝血酶是在凝血级联反应倒数第二步中，凝血酶原向凝血酶蛋白水解激活过程中产生的一种活性中间体。在结构上，中凝血酶与凝血酶不同，因为它保留了辅助性γ-羧基谷氨酸（Gla）结构域和两个kringle结构域。在功能上，中凝血酶与凝血酶一样，具有切割促凝血（纤维蛋白原）、促血栓形成（蛋白酶激活受体1，PAR1）和抗凝血（蛋白C）底物的能力，尽管其对纤维蛋白原和PAR1的特异性不太明显。在本研究中，我们报告了通过小角X射线散射（SAXS）和单分子荧光共振能量转移（FRET）解析的中凝血酶结构架构信息，其呈现为各个结构域的细长排列。此外，我们展示了一种中凝血酶构建体的特性，该构建体类似于目前正处于治疗血栓并发症和中风的I期临床试验阶段的抗凝血凝血酶突变体W215A/E217A。这些发现揭示了中凝血酶新的结构和功能方面，增进了我们对凝血酶原激活途径关键中间体的理解。
