ANTICOAGULANT PROTEIN COMPLEX STRUCTURE AND FUNCTION

抗凝蛋白复合物的结构和功能

基本信息

批准号：
6638726
负责人：
TIMOTHY A. MATHER
金额：
$ 24万
依托单位：
OKLAHOMA MEDICAL RESEARCH FOUNDATION
依托单位国家：
美国
项目类别：
财政年份：
2001
资助国家：
美国
起止时间：
2001-02-05 至 2005-07-31
项目状态：
已结题

项目摘要

DESCRIPTION (Applicant's Description Verbatim): The enzymatic phase of the anticoagulation system functions by the proteolytic digestion and down-regulation of the procoagulant cofactors factors VIIla and Va by the enzyme activated protain C(APC). Hereditary defects in this system lead to a congenital predisposition to venous thrombosis. The pathway is initiated when thrombin (T) binds to thrombomodulin (TM) on the endothelium and undergoes a cofactor dependent allosteric conformational change. In the TM bound conformation, thrombin loses its procoagulant activity, and gains an alternative substrate selectivity. The T-TM complex now recognizes the zymogen protein C as its substrate and very efficiently activates it. Thus, the major procoagulant enzyme takes on an anticoagulant activity and catalyzes its own down-regulation as a result of this cofactor induced allosteric modulation. The structural nature of this transition is completely unknown. If we could understand this specificity switch on a structural basis, we might begin to design therapeutic agents which could bind to thrombin and shift it from a procoagulant towards an anticoagulant activity. Based on the results of APC infusion in septic shock, this therapeutic approach leads to a wider window of efficacy without increased bleeding. We propose to study the structure and function of the T-TM complex with X-ray crystallography to understand the structural origin of thrombin's anticoagulant activity. We have grown diffracting crystals of one form of this complex and are currently solving its structure. We plan to build on this initial success to solve the structures of related complexes, each designed to show an additional aspect of this activity, and to apply our findings towards explaining the ability of some small molecules and thrombin point mutations to achieve partial anti-coagulant activity. Ultimately we will undertake structure based drug design to improve these partial effects.

描述（申请人的描述逐字描述）：抗凝系统通过蛋白水解消化和 procagulant辅助因子的下调Viila和VA的因素酶激活蛋白C（APC）。该系统中的遗传缺陷导致先天性对静脉血栓形成的易感性。当途径是在凝血酶（t）与内皮上的血栓形成蛋白（TM）结合并经历A 辅因子依赖性变构构象变化。在TM绑定中构象，凝血酶失去其凝聚活性，并获得替代底物选择性。 T-TM复合物现在识别Zymogen 蛋白C作为其底物，非常有效地激活它。因此，专业 procogulant酶具有抗凝活性并催化其自身由于该辅助因子引起的变构调制，因此下调。这这种过渡的结构性是完全未知的。如果我们能以结构性理解这种特异性转换，我们可能会开始设计可以结合到凝血酶并将其转移的治疗剂从促凝剂到抗凝活性。基于 APC在败血性休克中输注，这种治疗方法导致更宽的窗口功效而没有增加出血。我们建议研究结构和 X射线晶体学的T-TM复合物的功能以了解凝血酶抗凝活性的结构起源。我们已经成长了一种形式的衍射晶体，目前正在求解其结构。我们计划以这一最初的成功为基础，以解决相关的复合物，每个复合物都旨在显示此活动的附加方面，并应用我们的发现来解释一些小的能力分子和凝血酶点突变，以实现部分抗凝聚剂活动。最终，我们将进行基于结构的药物设计以改进这些部分影响。