【摘要】 用悬滴汽相扩散法得到了Ｒ１６３Ｋ ｎ － ＴＣＳ的晶体， 并用ＡＭＰ 浸泡４８ 小时后得到复合物晶体。在Ｍａｒ－ Ｒｅｓｅａｒｃｈ 面探测器系统上分别收集了０ ．２０５ 和０ ．１８７ｎ ｍ 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，最后两模型的偏差因子（Ｒ 和Ｒｆｒｅｅ） 分别为（０．１８７ 和０．２６３） 和（０．１８０ 和０．２３３） ，键长偏差都为０ ．００１３ｎｍ ， 键角偏差分别为２ ．７０８°和２ ．５８４°。结构测定显示Ｒ１６３Ｋ ｎ － ＴＣＳ 和Ｒ１６３Ｋ ｎ － ＴＣＳ／Ａｄｅ 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Ｒ１６３Ｋ ｎ － ＴＣＳ 具有糖苷酶活性，但活性降低。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。更多还原

【Abstract】 Crystals of R163K n-TCS and its Complex: R163K n-TCS/Ade were obtained by hanging drop vapor diffusion technique and soaking method. X-ray diffraction data of two crystals were collected respectively to 0.205 and 0.187nm,on Mar-Research IP. Two Structures were determined by Difference Fourier Method, the r.m.s. deviations of bond length were 0.0013nm and 0.0013nm,and r.m.s. deviations of bond angle were 2.708° and 2.584° respectively. Structure comparision indicates that there are no obvious changes between R163K n-TCS, R163K n-TCS/Ade and the original n-TCS, while the structures of the active pocket changed. Biochemical analysis suggests that R163K n-TCS has a lower glycosidase activity than native n-TCS. All findings suggest that the R163 is one of the critical residuals for N-glycosidase activity of n-TCS.更多还原