亚天花粉蛋白突变体(R163H n-TCS和R163Q n-TCS)的晶体结构研究  

CRYSTAL STRUCTURE OF R163H n-TCS and R163Q n-TCS

作　　者：李会广[1,2] 吴伸[1,2] 颜丽[1,2] 李建辉 黄岳顺[1,2] 施庆利 董贻诚[1,2] 

机构地区：[1]中国科学院生物物理所 [2]香港浸会大学生物系

出　　处：《生物物理学报》1999年第2期276-282,共7页Acta Biophysica Sinica

基　　金：国家自然科学基金;香港研究基金委员会基金;香港浸会大学院务研究基金

摘　　要：用悬滴汽相扩散法得到了Ｒ１６３Ｈｎ－ＴＣＳ和Ｒ６１３Ｑｎ－ＴＣＳ的晶体，在Ｍａｒ－Ｒｅｓｅａｒｃｈ面探测器系统上分别收集了０．２００和０．２０５ｎｍ分辨率的Ｘ－射线衍射数据。采用同晶差值傅立叶法解析结构，用Ｘ－ＰＬＯＲ软件包进行修正，最后的晶体学Ｒ因子分别为０．１８４和０．１８５，键长偏差分别为０．００１３ｎｍ和０．００１４ｎｍ，键角偏差分别为２．５９０°和２．８１５°。结构测定显示Ｒ１６３Ｈｎ－ＴＣＳ和Ｒ１６３Ｑｎ－ＴＣＳ与ｎ－ＴＣＳ的主链结构无较大变化，活性口袋区的结构和氢键体系发生了明显变化。生化分析表明Ｒ１６３Ｈｎ－ＴＣＳ具有糖苷酶活性，Ｒ１６３Ｑｎ－ＴＣＳ没有糖苷酶活性。这说明，第１６３位侧链的Ｈ＋对ｎ－ＴＣＳ发挥Ｎ－糖苷酶活性至关重要。Crystals of R163H n-TCS and R163Q n-TCS were grown by hanging drop vapor diffusion technique. X-ray diffraction data of two crystals were collected respectively to 0.200 and 0.205nm,on Mar-Research IP. The Structure were determined by Difference Fourier Method, the rms deviations of bond length were 0.0013nm and 0.0014nm,and r.m.s deviations of bond angle are 2.590° and 2.825° respectively. Structure determination indicates that there is no obvious change between R163H n-TCS, R163Q n-TCS and the original n-TCS, the structures of the active pocket remain unchanged. Biochemical analysis shows that suggests R163H n-TCS has the glycosidase activity while R163Q n-TCS has no. All findings suggest that the R163 is one of the critical residuels for N-glycosidase activity of n-TCS.

关 键 词：突变体 晶体结构 亚天花粉蛋白 

分 类 号：Q513.01[生物学—生物化学]