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首页> 外文期刊>Journal of Biomolecular Structure and Dynamics >Post Hartree-Fock studies of the canonical Watson-Crick DNA base pairs: molecular structure and the nature of stability.
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Post Hartree-Fock studies of the canonical Watson-Crick DNA base pairs: molecular structure and the nature of stability.

机译：规范的Watson-Crick DNA碱基对的Hartree-Fock后研究：分子结构和稳定性。

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Gas-phase gradient optimization was carried out on the canonical Watson-Crick DNA base pairs using the second-order Moller-Plesset perturbation method at the 6-31G(d) and 6-31G(d,p) basis sets. It is detected that full geometry optimization at the MP2 level leads to an intrinsically nonplanar propeller-twisted and buckled geometry of G-C and A-T base pairs; while HF and DFT methods predict perfect planar or almost planar geometry of the base pairs. Supposedly the nonplanarity of the pairs is caused by pyramidalization of the amino nitrogen atoms, which is underestimated by the HF and DFT methods. This justifies the importance of geometry optimization at the MP2 level for obtaining reliable prediction of the charge distribution, molecular dipole moments and geometrical structure of the base pairs. The Morokuma-Kitaura and the Reduced Variational Space methods of the decomposition for molecular HF interaction energies were used for investigation of the hydrogen bonding in the Watson-Crick base pairs. It is shown that the HF stability of the hydrogen-bonded DNA base pairs originates mainly from electrostatic interactions. At the same time, the calculated magnitude of the second order intramolecular correlation correction to the Coulomb energy showed that electron correlation reduces the contribution of the electrostatic term to the attractive interaction for the A-T and G-C base pairs. Polarization, charge transfer and dispersion interactions also make considerable contribution to the attraction energy of bases.
机译：气相梯度优化是在6-31G（d）和6-31G（d，p）基组上使用二阶Moller-Plesset微扰方法对规范的Watson-Crick DNA碱基对进行的。据检测，在MP2级别上进行完整的几何优化会导致G-C和A-T基对固有的非平面螺旋桨扭曲和弯曲几何。而HF和DFT方法可预测碱基对的完美平面或几乎平面的几何形状。据推测，成对的非平面性是由氨基氮原子的锥体化引起的，这被HF和DFT方法低估了。这证明了在MP2级别进行几何优化的重要性，以获得对电荷分布，分子偶极矩和碱基对的几何结构的可靠预测。分子HF相互作用能的分解的Morokuma-Kitaura方法和降变空间方法用于研究Watson-Crick碱基对中的氢键。结果表明，氢键结合的DNA碱基对的HF稳定性主要来自静电相互作用。同时，计算出的对库仑能量的二阶分子内相关校正的幅度表明，电子相关减少了A-T和G-C碱基对的静电项对吸引相互作用的贡献。极化，电荷转移和色散相互作用也为碱的吸引能做出了巨大贡献。

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