中文摘要：

目的 探究血管性血友病因子（von Willebrand factor,VWF）突变体G561S下调VWF-A1与其配体亲和力的分子机制。方法 分别构建2M型突变体G561S-A1（功能减弱型）、WT-A1（野生型）和2B型突变体R543Q-A1（功能增强型）3个分子系统。G561S-A1突变体采用将野生型A1结构的Gly561替换为Ser561的方式构建,WT-A1与R543Q-A1晶体结构取自蛋白质数据库（protein data bank,PDB）。利用自由分子动力学模拟方法对比分析WT-A1、G561S-A1、R543Q-A1三者构象的改变、柔性的变化以及氢键/盐桥的形成与演化。结果 G561S突变通过降低A1结构域α2螺旋的柔性,并增强N末端与body区的相互作用从而减弱其与配体GPIbα的亲和力,R543Q功能增强型突变体则启动了一条相反的调节路径。结论 局部动力学性质的改变是A1亲和力调控的潜在机制,研究结果有助于针对激活的A1结构域的变构药物设计以及相关抗血栓药物的研发。

英文摘要：

Objective To investigate the mechanism of affinity down-regulation between Von Willebrand factor mutant G561S and its ligand. Methods Three molecular systems were constructed for WT-A1, G561S-A1, and R343Q-A1, respectively. G561S-A1 mutant was constructed by replacing the Gly561 with Ser561 in the wild-type A1 domain. The crystal structures of WT-A1 and R543Q-A1 were downloaded from Protein Data Base （PDB）. Free molecular dynamics simulation was performed to observe the changes of conformation, alterations of flexibility, and the formation and evolution of hydrogen bond and/or salt bridge, among the three A1 domains （WT-A1, G561S-A1, and R543Q-A1）. Results G561S mutation lowered the localized dynamic properties of α2 helix and increased the interactions between the N-terminal arm and body region in A1 domain, thus leading to the decreased binding affinity with its ligand GPIbα. However, the Gain-of-function mutation R543Q followed the path- way which was contrary to G561S. Conclusions The change of localized dynamic properties of α2 helix is a potential mechanism in the regulation of the binding affinity of A1, and this research finding is helpful in developing allosteric drugs against the activated A1 domain and relevant anti-thrombus drugs.