甘油醛-3-磷酸脱氢酶与辅酶类似物ATP及底物磷酸结合特性的晶体学研究  

THE CRYSTALLOGRAPHIC STUDY OF THE COENZYME ANALOG ATP AND SUBSTRATE PHOSPHATE BINDING TO GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE

作　　者：王兆捷[1] 宋时英[1] 林政炯[1] 

机构地区：[1]中国科学院生物物理研究所生物大分子国家重点实验室

出　　处：《生物物理学报》1998年第4期609-616,共8页Acta Biophysica Sinica

摘　　要：气相扩散共晶生长法培养出Ｐ．ｖｅｒｓｉｃｏｌｏｒ龙虾肌ＡＴＰ－Ｄ－甘油醛－３－磷酸脱氢酶（ＡＴＰ－ＧＡＰＤＨ）的晶体。用同步辐射Ｘ光源－磷光储屏－Ｗｅｉｓｓｅｎｂｅｒｇ照相机系统收集了一套２．０分辨率的衍射数据。用同晶差值傅立叶法解析了其结构。精化后的结构模型最终Ｒ因子为０．１９７，与标准键长、键角的均方根偏差为０．０１６°和３．２０°。ＰｖＡＴＰ－ＧＡＰＤＨ结构总体上和Ｐｖａｐｏ－ＧＡＰＤＨ相似。ＡＴＰ分子的占有率较低，并表现出一定程度的无序性，提示ＡＴＰ与酶蛋白结合的稳定性较低，表明ＮＡＤ＋的尼克酰胺核苷部分与蛋白质分子的作用在辅酶与蛋白质的稳定结合中起关键作用。ＡＴＰ－ＧＡＰＤＨ中每个亚基只有一个磷酸结合位点（Ｐｉ）。认为无机磷酸结合位点Ｐｉ的形成不依赖于ＮＡＤ＋，而底物磷酸结合位点ＰＳ的形成则依赖于ＮＡＤ＋的存在。Lobster D-Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH) ATP complex was crystallized by vapour diffusion method. The diffraction data were collected with synchrotron radiation-imaging plate-weissenberg camera system at 2.0 resolution. The structure was determined with isomorphous difference method and refined by XPLOR program. The final R-factor of the ATP-GAPDH structure is 0.197 with r.m.s. deviations of 0.016 from the ideal bond lengths and 3.20° from the ideal bond angles. The structure of the ATP-GAPDH is similar to that of apo-GAPDH. ATP exists with low occupancy which is consistent with the result of biochemical experiment. The interactions between the nicotinamide moiety of the NAD+ and the GAPDH seem to be a key factor for coenzyme binding to GAPDH. There is only one phosphate binding site (Pi) in each subunit, indicating that NAD+ is necessary for the formation of substrate phosphate binding site Ps, but not necessary for the formation of inorganic phosphate binding site Pi.

关 键 词：GAPPH 晶体结构 ATP 磷酸结合位点 

分 类 号：Q554.02[生物学—生物化学]