Four Bases Score a Run: Ab Initio Calculations Quantify a Cooperative Effect of H-Bonding and π-Stacking on the Ionization Energy of Adenine in the AATT Tetramer
Four Bases Score a Run: Ab Initio Calculations Quantify a Cooperative Effect of H-Bonding and π-Stacking on the Ionization Energy of Adenine in the AATT Tetramer
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DOI：
10.1021/jz3011139
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发表时间：
2012-09-20
影响因子：
5.7
通讯作者：
Krylov, Anna I.
中科院分区：
文献类型：
--
作者：
Bravaya, Ksenia B.;Epifanovsky, Evgeny;Krylov, Anna I.
本文给出了（A：T）（2）（混合腺嘌呤-胸腺嘧啶）团簇的最低电离态的基准计算结果。本文报道并分析了用单取代和双取代的运动方程耦合团簇方法计算的垂直电离能。IE相对于单体（A）的位移为-0.7eV。广泛使用的B3 LYP，欧米茄B 97 X-D，和M06-2X泛函的性能方面的能力来描述能量和特性（本地化与离域）的电离状态也进行了研究。由氢键和堆叠相互作用引起的IE的位移进行了分析，在添加剂与合作的影响。结果表明，协同效应占IE相对于单体位移的20%以上。的合作效果，因此，位移的幅度很好地再现的混合量子力学/分子力学方案，其中中性胸腺嘧啶基地的点电荷表示。
Benchmark calculations of the lowest ionized state of the (A:T)(2) (mixed adenine thymine) cluster at the geometry taken from the DNA X-ray structure are presented. Vertical ionization energies (IEs) computed by the equation-of-motion coupled-cluster method with single and double substitutions are reported and analyzed. The shift in IE relative to the monomer (A) is -0.7 eV. The performance of the widely used B3LYP, omega B97X-D, and M06-2X functionals with respect to their ability to describe energetics and the character (localization versus delocalization) of the ionized states is also investigated. The shifts in IEs caused by H-bonding and stacking interactions are analyzed in terms of additive versus cooperative effects. It is found that the cooperative effect accounts for more than 20% of the shift in IE relative to the monomer. The cooperative effect and, consequently, the magnitude of the shift are well reproduced by the hybrid quantum mechanics/molecular mechanics scheme in which neutral thymine bases are represented by point charges.