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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Ca,Cd,Zn,and Their Ions Interacting with Cytosine:A Theoretical Study
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Ca,Cd,Zn,and Their Ions Interacting with Cytosine:A Theoretical Study

机译：Ca，Cd，Zn及其离子与胞嘧啶相互作用的理论研究

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Metal atoms play a major role in the chemical behavior of biological systems.In this work,known issues of the metal-base interactions,such as the stabilization of different tautomers of cytosine that could be incompatible with the DNA double helix,are researched using DFT methods.Ca-,Zn-,and Cd-cytosine in neutral and ionic forms were studied at the B3LYP/LANL2DZ level.Several neutral and ionic isomers were found within an interval of 10 kcal/mol of relative stability,with the most stable isomer in each group being a compound derived from the canonical isomer of cytosine,except for the dications where two iso-energetic isomers were found.Interatomic lengths from each metal atom to the nearest atoms in cytosine's ring were larger than 2 A,discouraging the possibility of a covalent interaction,as supported by additional evidence from molecular orbitals.The interaction between metal and cytosine,electrostatic in nature,is reinforced with the increase of the metal's nuclear charge.Additionally,the ionization energies of the metal-cytosine compounds exhibit a significant reduction(below 6 eV)compared with that of plain cytosine(8.7 eV),posing an interesting possibility with respect to the experimental determination of the photoelectron spectra of these compounds.Analyses of the energetics of the global reactions to form cationic species show that metal cations bind more strongly to neutral cytosine than to neutral metals.Metal dications form the most stable compounds with neutral cytosine,and the stabilities of these systems decrease as(Zn-cyt)~(2+)>(Cd-cyt)~(2+)>(Ca-cyt)~(2+).Aromaticities computed via the HOMA indexes also support the observation regarding the greater affinity of cytosine for metal cations.
机译：金属原子在生物系统的化学行为中起着重要作用。在这项工作中，使用DFT研究了金属碱相互作用的已知问题，例如可能与DNA双螺旋不相容的胞嘧啶的不同互变异构体的稳定性。方法：在B3LYP / LANL2DZ水平上研究了中性和离子形式的Ca，Zn和Cd-胞嘧啶，在相对稳定性10 kcal / mol的间隔内发现了几种中性和离子异构体，其中最稳定的异构体每个组中的化合物都是由胞嘧啶的正构异构体衍生的化合物，但发现有两个同能异构体的药物除外。从每个金属原子到胞嘧啶环中最近的原子的原子间长度均大于2 A，从而降低了金属分子与胞嘧啶之间的相互作用，本质上是静电的，随着金属核电荷的增加而增强。基本上，金属胞嘧啶化合物的电离能比普通胞嘧啶的电离能显着降低（低于6 eV）（8.7 eV），这为这些化合物的光电子光谱的实验确定提供了一个有趣的可能性。形成阳离子物种的整体反应的高能学研究表明，金属阳离子与中性胞嘧啶的结合比与中性金属的结合更强。金属离子与中性胞嘧啶形成最稳定的化合物，并且这些系统的稳定性随着（Zn-cyt）的降低而降低〜（2 +）>（Cd-cyt）〜（2 +）>（Ca-cyt）〜（2+）。通过HOMA指数计算出的芳香性也支持关于胞嘧啶对金属阳离子的更大亲和力的观察。

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