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在酸性条件下(pH=5.4)培养出正交晶系天花粉蛋白晶体。用面探测器收集了X射线衍射强度数据。以C2空间群天花粉蛋白2.6分辨率的晶体结构中的分子模型作为已知结构模型,用分子置换法解出正交晶系P2_12_12_1空间群天花粉蛋白的晶体结构。所得到的初始结构模型先后用模拟退火法和立体化学制约的最小二乘修正技术对原子坐标及温度因子进行修正。最后在2.4分辨率范围内模型的β因子为0.197,键长的均方根误差为0.021,键角距离的均方根误差为0.081。分子结构模型与(2Fo—Fc)为系数的电子云密度图吻合得很好。键长键角合理。结构测定结果表明,P2_12_12_1;空间群天花粉蛋白的分子的空间结构与单斜晶系C2空间群中的分子结构甚为相似。
Orthogonal crystal trichosanthin crystals were grown under acidic conditions (pH = 5.4). X-ray diffraction intensity data was collected using a surface detector. The crystal structure of TCS in the space group P2_12_12 of the orthorhombic crystal was solved by using the molecular model in the crystal structure of C2 space trichosanthin at a resolution of 2.6 as the known structural model. The resulting initial structural model has been modified by the simulated annealing method and the least-squares correction technique of stereochemical constraints on the atomic coordinates and temperature factors. Finally, in the 2.4 resolution range, the β factor of the model was 0.197, the root mean square error of the bond length was 0.021, and the root mean square error of the bond angle distance was 0.081. Molecular structure model and (2Fo-Fc) as the coefficient of electron cloud density map in good agreement. Key long key angle reasonable. The results of structure determination showed that the molecular structure of space trichosanthin in P2_12_12_1 was very similar to that in monoclinic C2 space group.