正交晶系天花粉蛋白2.4分辨率的晶体结构和分子结构  

Structure of Orthorhombic Crystal of Trichosanthin at 2. 4 Resolution

作　　者：周康靖[1] 傅珠玑 陈明晃[1] 林玉娟[1] 潘克桢[1] 

机构地区：[1]中国科学院福建物质结构研究所,福州350002

出　　处：《Chinese Journal of Structural Chemistry》1992年第6期401-406,共6页结构化学（英文）

摘　　要：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。Trichosanthin is one of the ribsome inactivating proteins (RIPs) extracted from a Chinese herb medicine, the root tuber of Trichosanthes, Kirilowii, Maxim Cucurbitaceae. It consists of 247 amino acids with Mr = 27132 D. The orthorhombic crystals of trichosanthin have been obtained by using hangingdrop method. The crystal belongs to the space group P21212i with a = 38. 305,6 = 76. 221, c=79. 213(?). The X-ray intensity data of 8852 reflections were collected on a Siemens X - 200B area detector. The structure was solved bymolecule replacement methods and refined using the programs of XPLOR and PROLSQ to an R-factor of 0. 197. The r. m. s. deviations of bond length and bond angle are 0. 02l(?) and 0. 081(?), respectively. Trichosanthin molecule can be divided into two structural domains. The molecule contains 8 α helices and 13 β sheets. The active site of the molecule is located in the valley region between two domains. Comparing with the structure of monoclinic crystal of trichosanthin, it is shown little differences between the two structures.

关 键 词：正交晶系 天花粉蛋白 晶体结构 

分 类 号：O51[理学—低温物理]