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题目所指化合物晶体属单斜晶系,空间群P2_1/a,晶胞参数a=10.256,b=14.809,c=7.171,B=103.4°晶胞中分子数Z=4,晶体密度Dc=1.62gcm~(-3)。由直接法和傅里叶(Fourier)综合解得粗结构,经块对角矩阵最小二乘修正,偏离因子R为0.047。N→Si配位键键长为2.062,三个五员环近乎120°角相交,扭角分别为18.64°,19,34°和18.45°。环上的C(12),C(22),C(32)均偏离环的同一侧,三个环呈风扇形,两个氯原子与三个氧原子呈交叉构象。 相似文献
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柳珊瑚酸的分子结构和绝对构型 总被引:1,自引:0,他引:1
本文首次应用X射线单晶衍射法证实了一种新的倍半萜骨架,并测定了柳珊瑚酸的分子结构和绝对构型。柳珊瑚酸的晶体属于正交晶系,空间群:D_2~ -P2_12_12_1,晶胞参数:a=16.135,b=13.189,c=12.901,α=β=γ=90°。单胞中分子数为8,不对称单位含两个分子,用直接法导出全部非氢原子位置,经最小二乘法修正后,最终偏离因子R=0.056。文中还对柳珊瑚酸分子的结构进行了讨论,并对核磁共振溶剂效应有关理论进行了较深入的讨论,初步探讨了分子结构与其毒性之间的关系。 相似文献
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本文应用差值Fourier技术和制约立体化学参数最小二乘技术以二锌猪胰岛素模型为起点测定了1.9分辨率的(D-Ala)~(B0)猪胰岛素晶体结构,R因子为0.211,键长均方差为0.057。B_0残基的电子密度表现清晰。B_0的引入降低了B链N端肽段构象的运动性,使分子在晶体中的堆积更加紧密。(D-Ala)~(B0)猪胰岛素和二锌猪胰岛素结构的主要差异在于分子可能的受体结合表面中部分极性基团的构象和分子IA链两段螺旋的组装。(D-Ala)~(B0)猪胰岛素B链N端晶体学微环境与(Trp)~(B1)猪胰岛素和去B_1牛胰岛素有很大的差异。本文还简单地讨论了胰岛素分子结构与免疫功能的关系。 相似文献
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The crystal structure of (D-Ala)-B0 porcine insulin has been determined, using data to 1.9 and atomic parameters of 2 Zn porcine insulin as a starting model, and through the use of the difference method and the restrained least square method, to a final R-factor of 0.211 and r. m. s. deviation of 0.057 for the bond lengths. The electron densities of B0 residues were very clear. Introduction of B0 residues into the molecules had reduced the thermal vibration of the N-terminus of B-chain for both molecules Ⅰ and Ⅱ and made the molecules pack closer in the crystal The obvious differences between the crystal structures of 2 Zn and (D-Ala)-B0 porciue insulin were the conformations of partial polar groups around the possible receptor binding surface and the assembly mode of two helixes of A-chain in molecule I. In the local environment of the N-terminus of Bchain there were great differences between the crystal structures of(D-Ala)-B0 porcine insulin, (Trp)-B1 porcine insulin and Des B1(Phe) bovine insulin. 相似文献
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In the present paper it is reported that the molecular structure and absolute configuration of poisonous suberogorgin are determined by using X-ray diffraction method. The crystal of suberogorgin belongs to orthogonal system with space group D_2~4-P2_12_12_1. The crystallographic parameters are: a=16.135, b=13.189, c=12.901, Z=8. The initial model of the crystal structure was solved by the direct method. The refinement of the strueture parameters was carried out by using the least square method and led to a final R-factor of 0.056. In accordance with the molecular structure of suberogorgin mentioned above, the solvent effect of NMR has been further discussed and the relationship between the molecular structure of suberogorgin and its toxicity has also been preliminarily investigated. 相似文献
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