Melnikov Petr, Nascimento Valter A, Silva Anderson F, Consolo Lourdes Z Z
School of Medicine of the Federal University of Mato Grosso do Sul/UFMS, Caixa Postal 549, Campo Grande/MS, Brazil.
Molecules. 2014 Apr 17;19(4):4847-56. doi: 10.3390/molecules19044847.
The comparative structural modeling of djenkolic acid and its derivatives containing selenium and tellurium in chalcogen sites (Ch=Se, Te) has provided detailed information about the bond lengths and bond angles, filling the gap in what we know about the structural characteristics of these aminoacids. The investigation using the molecular mechanics technique with good approximation confirmed the available information on X-ray refinements for the related compounds methionine and selenomethionine, as well as for an estimate made earlier for telluromethionine. It was shown that the Ch-C(3) and Ch-C(4) bond lengths grow in parallel with the increasing anionic radii. Although the distances C-C, C-O, and C-N are very similar, the geometry of conformers is quite different owing to the possibility of rotation about four carbon atoms, hence the remarkable variability observed in dihedral angles. It was shown that the compounds contain a rigid block with two Ch atoms connected through a methylene group. The standard program Gaussian 03 with graphical interface Gaussview 4.1.2 has proved to be satisfactory tool for the structural description of less-common bioactive compositions when direct X-ray results are absent.
对含有硫族元素（Ch = Se、Te）的jenkolic酸及其衍生物在硫族元素位点的比较结构建模，提供了有关键长和键角的详细信息，填补了我们对这些氨基酸结构特征认识上的空白。使用分子力学技术进行的研究以良好的近似度证实了有关相关化合物蛋氨酸和硒代蛋氨酸的X射线精修的现有信息，以及先前对碲代蛋氨酸所做的估计。结果表明，Ch - C(3)和Ch - C(4)键长随着阴离子半径的增加而平行增长。尽管C - C、C - O和C - N的距离非常相似，但由于围绕四个碳原子旋转的可能性，构象异构体的几何形状有很大不同，因此在二面角中观察到显著的变异性。结果表明，这些化合物包含一个刚性结构单元，其中两个Ch原子通过一个亚甲基相连。当缺乏直接的X射线结果时，带有图形界面Gaussview 4.1.2的标准程序Gaussian 03已被证明是用于描述不太常见生物活性成分结构的令人满意的工具。
