【作者】 赵亚英；

【导师】 周立新；

【作者基本信息】 福州大学 ， 物理化学， 2004， 硕士

【摘要】 本文第一部分用量子化学从头算方法对金属离子与核酸大分子活性位点相互作用的选择性及其配合物的结构和性质进行较为系统的理论研究，以期探究金属离子在生物体内的功能及其作用实质。金属离子易与核酸的磷酸酯骨架、碱基的环氮相互作用。腺嘌呤有两个环氮，可作为相同碱基不同位点对金属离子配位选择性研究的代表。第二章在B3LYP/6-31G**水平，全优化Mg2+、Ca2+、Mn2+、Co2+、Zn2+、Cu2+、Ni2+、Cd2+(用有效实势(ECP)方法处理)与腺嘌呤的N1和N7位点配位的两类配合物气相结构，后采用Onsager模型研究水溶液中配合物的结构和稳定性规律。通过研究得到金属对N7位的相对优选顺序为：Co2+>Mg2+>Cd2+>Ca2+> Zn2+>Mn2+>Ni2+>Cu2+，与实验结果基本吻合。实验认为金属离子多与GC碱基对作用，第三章在B3LYP/6-31G**水平，用全电子从头算研究了Ia、部分IIa和部分Ib族金属离子(重原子用ECP方法处理)与GC碱基对的相互作用，结果表明主族金属离子与GC对间以静电作用为主，而副族金属离子共价作用成分较大。第四章在B3LYP/6-31G**水平上，全电子研究了Mg2+、Ca2+、Mn2+、Co2+、Ni2+、Cu2+、Zn2+与磷酸二甲酯阴离子(DMP-)“双齿”配位模式下的相互作用，并且用四个水分子“饱和”各金属离子六配位模式下的其他位点。结果表明DMP-对于上述金属离子的选择性顺序为：Cu2+>Ni2+>Zn2+> Co2+>Mg2+>Mn2+>Ca2+，与Irving-Williams序列基本一致。通过NBO 分析，讨论了配位键的相互作用能。第五章研究了碱基与金属离子水合物。结果指出G、C对Mg2+、Mn2+、Ni2+、Cu2+、Zn2+的选择性顺序分别为：aCu2+>aNi2+> aZn2+>aMg2+>bCu2+>aMn2+>bZn2+>bNi2+；aCu2+>aNi2+>aZn2+>bCu2+>aMg2+>bZn2+> bNi2+>aMn2+，基本和DNA重卷实验结果相符。 氨基酸与RNA碱基间的选择性在生命起源，基因表达和蛋白质合成过程中起着极其重要的作用，本文第二部分在B3LYP/6-311++G**水平，全优化了L－亮氨酸&碱基的16种二聚物结构。通过结构参数比较和相互作用分析得到RNA各碱基对L-亮氨酸的亲合性顺序为：G>C>A≈U，与实验符合的相当好。更多还原

【Abstract】 The selectivity of the active sites of biomacromolecules— nucleic acid with metal cations were studied by using the density functional theory with a hybrid B3LYP exchange-correlation functional and 6-31G** basis set in the first part of this paper, the structures and properties of complexes were systemically investigated, and the function of metal cations in organism was testified or forecasted. The interaction of adenine with Mg2+, Ca2+, Mn2+, Co2+, Zn2+, Ni2+, Cu2+ and Cd2+ cations were calculated with DFT/B3LYP method by using the standard 6-31G(d,p) basis set. Effective core potential (ECP) was used for Cd2+. The calculations of stabilities of the complexes in a polar medium have been performed with Onsager solvation model. All geometries were optimized without symmetry restrictions. The interaction energies and interaction Gibbs energies of complexes provide a comparatively reliable quantification of the selectivity of adenine for the studied metal ions not only in gas but also in the polar medium (water ε = 78.39), and relative interaction Gibbs energies of the isomer of the complexes have shown the selectivity of different metal-binding sites of the ligands, as to N7, the order is Co2+ > Mg2+ >Cd2+ > Ca2+ >Zn2+ > Mn2+ > Ni2+ > Cu2+.The interactions of guanine-cytosine pair with Li+、Na+、K+、Cu+、Mg2+、Ca2+、Cu2+、Zn2+、Cd2+、Ba2+、 Hg2+ cations were computed with DFT/B3LYP method using the standard 6-31G(d,p) basis set. Effective core potentials (ECP) were used for Cd2+、Ba2+、Hg2+. All geometries were fully optimized without symmetry restrictions as well, while the calculations of the single point energy of the complexes in a polar medium have been performed using Onsager solvation model. Interaction energies of complexes provide an comparatively reliable order of the complexes’ stability, and the mechanism of interaction of complexes is shown by the analysis of the energies—the interaction between the metal ions of subgroup A and bases is mainly composed of electrostatic attraction, while the covalent bonds play an important role in the complexes of metal ions of subgroup B and bases, which may be the cause of the differences between various complexes and is in reasonable agreement with the analysis of the charges and the orbital of the complexes too. <WP=7>The interactions of dimethyl phosphate anion (DMP－) with Mg2+, Ca2+, Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ cations were calculated with DFT/B3LYP method by using the standard 6-31G(d,p) basis set too, while the remaining coordination bonds are saturated with water molecules ((H2O)4). All geometries were optimized without symmetry restrictions. The interaction energies of complexes provide a comparatively reliable quantification of the selectivity of dimethyl phosphate anion for the studied metal ions, which is in reasonable agreement with the Irving-Williams list. Moreover, the cations with an unfilled state of d-electrons may be sensitive to the changing of ligands. In addition, the population of changes of the complexes and the significant donor-acceptor natural bond orbital interaction were analyzed with the method of Natural Bond Orbital analysis. The interactive system of bases groups representing the single chain of DNA with Mg2+, Mn2+, Ni2+, Cu2+, Zn2+ cations were computed with the same method. All geometries were optimized without symmetry restrictions. Interaction energies of complexes provide a comparatively reliable quantification of the selectivity of dimethyl phosphate anion for the studied metal ions, which is in reasonable agreement with the experiment, as to guanine: aCu2+>aNi2+>aZn2+>bCu2+> aMg2+>bZn2+>bNi2+>aMn2+; as to cytosine: aCu2+>aNi2+>aZn2+>aMg2+>bCu2+>aMn2+>bZn2+>bNi2+. In addition, interplay between the structure of the complexes and coordinator number and their stability, measured by the values of interaction energies, has been discussed. A total of 16 hydrogen bonded complexes between the lowest energy tautomers of L-leucine and each of bases of RNA have been characterized at the density functional level of theory更多还原