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本文报道了用面探测器收集一套1.73分辨率天花粉蛋白(TCS)正交晶体的X射线衍射数据,利用已知的α苦瓜子蛋白模型,取10—4范围的TCS强度数据,应用分子置换法测定了晶体结构,并且采用限制参数最小二乘法在10—1.73分辨率范围内修正模型结构。修正结果,晶体学R因子为0.186,键长标准偏差为0.013,键角标准偏差为2.48°,一个不对称单位中找到133个水分子。本文详细描述了天花粉蛋白分子的结构、温度因子、氢键、结合水、保守残基的分布以及分子间相互作用。保守残基14Tyr的羟基与157位的羰基氧形成的氢键,对维持活性部位构象有重要作用;保守残基160Glu和它在活性部位的构象对酶的催化活性起着关键性作用。
In this paper, we report the collection of a set of 1.73 TCS orthorhombic crystals by using X-ray diffraction data. Using the known α-bitter melon seed protein model, we take TCS intensity data of 10-4 range, The crystal structure was determined by the displacement method, and the model structure was corrected by using the least square method of the limiting parameter in the resolution range of 10-1.73. As a result of the correction, the R factor of the crystallography was 0.186, the standard deviation of the bond length was 0.013, the standard deviation of the bond angle was 2.48 °, and 133 water molecules were found in one asymmetric unit. This article describes in detail the structure, temperature factor, hydrogen bonding, binding water, distribution of conserved residues, and intermolecular interactions of trichosanthin molecules. The hydrogen bond between the hydroxyl group at conserved residue 14Tyr and carbonyl oxygen at position 157 plays an important role in maintaining the conformation of the active site. Conserved residue 160Glu and its conformation at the active site play a key role in the catalytic activity of the enzyme.