中文摘要：

RecQ解旋酶是生物分子代谢过程中重要的大分子物质，对保持遗传物质的稳定性具有重要作用。枯草芽孢杆菌（Bacillussubtilis）RecQ解旋酶中精氨酸可能在其对ATP水解和结合中起到重要的作用。通过PCR以Bacillussubtilis168中抽提的基因组DNA为模板扩增得到大小为1．5kb的RecQ基因片段，并用重叠PCR定点突变法将该RecQ基因中的精氨酸残基（arg319和arg322）分别进行单突变和双突变，并将野生型和突变型基因克隆入原核表达载体pET24a（-4-）中，转化大肠杆菌E．coliBL21（DE3），IPTG诱导表达，所有目的蛋白主要以可溶形式存在于菌体中。优化表达条件后，经镍柱螯合亲和层析纯化获得纯度大于90％的目标蛋白质，检测野生型和突变型蛋白的ATP水解活性。结果表明，BacillussubtilisRecQ解旋酶具有DNA依赖性和蛋白浓度依赖性的ATP水解活性。其arg319和arg322突变后，RecQ酶的ATP水解活性明显减弱，表明这两个精氨酸残基参与RecQ酶与ATP的相互作用。实验为RecQ解旋酶家族其他重要成员的活性功能研究提供了理论依据和重要参考。

英文摘要：

RecQ helicases are one of the most important macromolecules in the process of molecular metabolism. They play essential roles in maintaining the stability of the genetic materials in cells. The arginine residues of Bacillus subtilis RecQ play important roles in ATP hydrolyzation and binding activities. The DNA corresponding to the coding sequence of the Bacillus subtilis RecQ helicase gene was amplified by PCR from the chromosome DNA of Bacillus subtilis 168, the sequence size is about 1.5kb. The arginine residues （arg319 and arg322） of Bacillus subtilis RecQ were mutated separately or simultaneously to alanine residues by overlapping PCR method, then wild type and mutants were subcloned into the expression vector pET24a （ ＋ ）. The recombinant proteins were induced to express in E. coli BL21 （DE3） with IPTG. All of the proteins obtained in vitro were with above 90% purity and good solubility, and then the ATP hydrolysis of wild type and mutants were detected. The results showed that Bacillus subtilis RecQ and mutants had DNA-dependent ATPase activity in concentration-dependent manner. However, the ATP hydrolysis activities of mutants were significantly reduced compared to the wild RecQ. The consequence state that the two arginine residues took important part in interacting RecQ helicaese with ATP. These results are helpful to study the structures and functions of other members of the RecQ family helicases.