脯氨酸与Zn~(2+/1+/0)相互作用及性质

运用M062X和X3LYP两种密度泛函理论(DFT)方法在TZVP和6-311++G(2d,p)+LANL2DZ基组水平上,对已报道的15种脯氨酸(Pro)构象分别与Zn2+、Zn+及Zn进行不同方式配位体系的几何结构、能量学特征、振动光谱和电子结构性质进行了计算研究.Pro-Zn2+、Pro-Zn+和Pro-Zn三种体系分别得到19、21和24种稳定结构.Pro-Zn2+体系中Zn2+与Pro两性离子的氧端(OO)配位形成的四元环结构能量最低,其次是与Pro羧羰基氧和亚氨基氮配位形成的五元环结构,而Pro-Zn+体系与之相反.Pro-Zn2+/1+/0体系的相对能差逐渐降低,结合能分别位于-620--936,-139--325和-1.5--22 kJ·mol-1范围,配位Pro的变形能随价态降低而减小.ProZn2+体系受方法和基组影响较大,离子体系中Zn均获得少量负电荷,所有配位化合物的前线轨道能差均比相应两个碎片要低.

Interaction and Properties of Proline-Zn2+/1+/0 Complexes

The hybrid density functional theory (DFT) methods M062X and X3LYP with the TZVP and 6-311++G(2d, p)+LANL2DZ basis sets were used to calculate the complexes formed between fifteen proline (Pro) conformers and Zn^2+/1+/0. The geometrical structures, energetics, vibrational frequencies, and electronic structures were investigated in detail. We obtained 19, 21, and 24 stable complexes for Pro-Zn^2+/1+/0 at the four levels. The most stable Pro-Zn²⁺ structure was a four-membered ring with Zn²⁺ bound to both oxygen ends (OO) of the zwitterionic proline, and the next stable compound was a five-membered ring with Zn²⁺ coordinated to both the amino nitrogen and carbonyl oxygen (NO) of proline, but Zn⁺ showed opposite behavior. The relative energy difference and the deformation energy of coordinated Pro decreased gradually with a reduction in the charge number of Zn. The binding energy of the Pro-Zn^2+/1+/0 systems are in the -620 to -936, -139 to -325, and -1.5 to -22 kJ·mol^-1 ranges, respectively. The properties of the Pro-Zn²⁺ system were significantly different when using different methods and basis sets. Both cationic systems indicated some charge transfer from Pro to Zn. The energy difference values for the frontier orbitals of all the complexes are lower than those of the corresponding fragments.