中文摘要：

大肠杆菌分子伴侣蛋白Dna K氮端核苷酸结合域（NBD,nucleotide-binding domain）的II-A和II-B子域之间的一些高度保守的扭链残基突变后（I202A,S203A,G223A,L227A,G228A）,其ATPase活性也发生变化原因不清楚。我们通过同源建模的方法构建NBD与小分子ATP相互作用的各蛋白模型,使用分子动力学模拟方法研各模型的结构变化并尝试找出其与ATPase活性变化的关系。结果表明,除L227A外,所有突变模型T11烃基与ATP-γ磷酸基团间的距离与活性变化间具有明显规律;但是所有模型中,能影响与Dna J结合,从而影响ATPase活性的β220（214-221）部分的紧致性变化符合规律,进一步的蛋白对接实验证实了这一点,所以这些扭链残基突变体可能主要是通过这两个部分的变化,引起ATPase活性的改变。

英文摘要：

When the highly conserved hinge residues（ I202,S203,G223,L227,G228）,which are located in the subdomain II-A and II-B of NBD（ Nucleotide binding domain） in the E.coil＇s Dnak,mutate into alanine. It is not clear that the change reason of ATPase activity. We build all of the wild type and mutant protein model which contain small molecule ATP by using the method of homologous modeling,than using the molecular dynamics simulation（ MDs） to study the comformational change of these mutants,and want to find the relationship with the change of ATPase activity. Results show that the distances between the hydroxyl of Tyr11 residue and the γphosphate of ATP in all models expect L227 A have obvious rules with the activity of ATPase; but the change of compactness in β220（ 214- 221）,which can impact the binding of Dna J and effect the activity of ATPase,conform to the rules. The further experiment of protein docking confirm it,so the mutants of hinge residues may influence the ATPase activity by the changes of these two parts.