4hfp | pdb_00004hfp
Structure of thrombin mutant S195a bound to the active site inhibitor argatroban
Structural highlights
DiseaseTHRB_HUMAN Defects in F2 are the cause of factor II deficiency (FA2D) [MIM:613679. It is a very rare blood coagulation disorder characterized by mucocutaneous bleeding symptoms. The severity of the bleeding manifestations correlates with blood factor II levels.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] Genetic variations in F2 may be a cause of susceptibility to ischemic stroke (ISCHSTR) [MIM:601367; also known as cerebrovascular accident or cerebral infarction. A stroke is an acute neurologic event leading to death of neural tissue of the brain and resulting in loss of motor, sensory and/or cognitive function. Ischemic strokes, resulting from vascular occlusion, is considered to be a highly complex disease consisting of a group of heterogeneous disorders with multiple genetic and environmental risk factors.[13] Defects in F2 are the cause of thrombophilia due to thrombin defect (THPH1) [MIM:188050. It is a multifactorial disorder of hemostasis characterized by abnormal platelet aggregation in response to various agents and recurrent thrombi formation. Note=A common genetic variation in the 3-prime untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and an increased risk of venous thrombosis. Defects in F2 are associated with susceptibility to pregnancy loss, recurrent, type 2 (RPRGL2) [MIM:614390. A common complication of pregnancy, resulting in spontaneous abortion before the fetus has reached viability. The term includes all miscarriages from the time of conception until 24 weeks of gestation. Recurrent pregnancy loss is defined as 3 or more consecutive spontaneous abortions.[14] FunctionTHRB_HUMAN Thrombin, which cleaves bonds after Arg and Lys, converts fibrinogen to fibrin and activates factors V, VII, VIII, XIII, and, in complex with thrombomodulin, protein C. Functions in blood homeostasis, inflammation and wound healing.[15] Publication Abstract from PubMedTrypsin-like proteases are synthesized as inactive zymogens and convert to the mature form upon activation by specific enzymes, often assisted by cofactors. Central to this paradigm is that the zymogen does not convert spontaneously to the mature enzyme, which in turn does not feed back to activate its zymogen form. In the blood, the zymogens prothrombin and prethrombin-2 require the prothrombinase complex to be converted to the mature protease thrombin, which is unable to activate prothrombin or prethrombin-2. Here, we show that replacement of key residues within the activation domain causes these zymogens to spontaneously convert to thrombin. The conversion is started by the zymogen itself, which is capable of binding ligands at the active site, and is abrogated by inactivation of the catalytic residue Ser-195. The product of autoactivation is functionally and structurally equivalent to wild-type thrombin. Zymogen autoactivation is explained by conformational selection, a basic property of the trypsin fold uncovered by structural and rapid kinetics studies. Both the zymogen and protease undergo a pre-existing equilibrium between active and inactive forms. The equilibrium regulates catalytic activity in the protease and has the potential to unleash activity in the zymogen to produce autoactivation. A new strategy emerges for the facile production of enzymes through zymogen autoactivation that is broadly applicable to trypsin-like proteases of biotechnological and clinical interest. Autoactivation of thrombin precursors.,Pozzi N, Chen Z, Zapata F, Niu W, Barranco-Medina S, Pelc LA, Di Cera E J Biol Chem. 2013 Apr 19;288(16):11601-10. doi: 10.1074/jbc.M113.451542. Epub, 2013 Mar 6. PMID:23467412[16] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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