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多对同晶置换和反常散射法是目前测定生物大分子晶体结构的主要方法。这一方法可以概括为以下五个步骤; 1.培养出适用于衍射的蛋白质晶体。 2.制备两个以上与蛋白质母体同晶型的重原子衍生物。 相似文献
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D-glyceraldehyde-3-phosphate dehydrogenase (holo-GAPDH) from Palinurus versicolor was crystallized in a novel crystal form by the method of sitting-drop vapor diffusion. The crystals have space group P4212, cell parameters a=15.49 nm, c=8.03 nm and two subunits per asymmetric unit. The crystal structure at 0.34 nm was determined by the molecular replacement method. The final model has crystallographic Rfree and R factors of 0.274 and 0.262, and r.m.s. deviations of 0.002 nm for bond lengths and 2.33?for bond angles. The two subunits in asymmetric unit are similar to each other not only in the three-dimensional structure, but also in average temperature factors. This result demonstrates that the obvious difference in average temperature factors for the different subunits in C2 crystal form reported previously may be attributed to the different crystallographic environments of the subunits. This further supports that holo-GAPDH has a good 222 molecular symmetry. 相似文献
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从江浙蝮蛇中分离纯化的碱性磷脂酶A2在pH9.5,0.05mmol/LCHES缓冲液中,用汽相悬滴扩散的方法,获得了适用于高分辨率X射线结构分析的单晶.经X200B面探测器分析,表明该晶体属于正交晶系,P2I2I2I空间群,晶胞参数为a=97.13,b=103.69,c=23.27.并收集了一套衍射数据,独立衍射点数12001个,数据完整度为86.2%,Rmerge为0.0459.最高分辨率达2.0,根据分子量与晶胞体积估算,一个不对称单位含两个分子. 相似文献
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龙虾甘油醛-3-磷酸脱氢酶结构中的氢键 总被引:1,自引:1,他引:0
甘油醛-3-磷酸脱氢酶(GAPDH)是一种具有别构作用的寡聚酶。根据X射线晶体学研究得到的中国南海龙虾P.versicolorholo-GAPDH高分辩率三维结构显示复杂的氢键结构,对各种类型氢键的分布和几何性质进行了统计分析。这个寡聚蛋白氢键的特性总体上与单体蛋白类似。几乎所有位于亚基间界面的极性侧链都能形成氢键,并满足能量上有利的几何学要求 相似文献
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The basic phospholipase A2 from the venom of Agkistrodon halys Pallas is a potent hemolytic toxin and anticoagulant. The accurate rotation and translation parameters of the molecules in orthorhombic crystal form I were successfully obtained using the fitting refinement technique. The structure was refined in the resolution range of 0. 6-0.25 nm using least square refinement with non-crystallographic two fold symmetry restraint, and resulted in the final R factor of 20.1 % , and the rms deviations from ideal stereochemistry were 0. 001 3 nm for bond lengths and 1. 32° for bond angles. The overall architecture of the present structure was similar to that of the determined structure of the orthorhombic crystal form Ⅱ, with a few differences in the regions of the β-wing and Ca2 -binding loop. The dimers formed by the two molecules in the asymmetric unit in both crystal forms were also similar. However, one of the monomers showed an orientational difference of 5.5° along the dimer interface in the two cr 相似文献
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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。 相似文献