波谱学杂志 ›› 2016, Vol. 33 ›› Issue (3): 378-394.doi: 10.11938/cjmr20160303

• 研究论文 • 上一篇    下一篇

分子间相互作用对核酸碱基中17O屏蔽张量与四极耦合常数影响的理论计算研究

宋本腾1,2, 褚月英2, 王吉清1, 郑安民2, 邓风2   

  1. 1. 湖南工业大学, 绿色包装与生物纳米技术应用省重点实验室, 湖南 株洲 412008;
    2. 波谱与原子分子国家重点实验室(中国科学院 武汉物理与数学研究所), 湖北 武汉 430071
  • 收稿日期:2015-09-22 修回日期:2016-07-12 出版日期:2016-09-05 发布日期:2016-09-05
  • 通讯作者: 王吉清,E-mail:wjqwh2006@163.com;郑安民,电话:027-87197127,E-mail:zhenganm@wipm.ac.cn. E-mail:wjqwh2006@163.com;zhenganm@wipm.ac.cn
  • 作者简介:宋本腾(1990-),男,山东鄄城县人,硕士研究生,分析化学专业.
  • 基金资助:

    国家自然科学基金资助项目(21522310,21173255),湖南省教育厅重点资助项目(14A040).

Influences of Intermolecular Interactions on the 17O Nuclear Magnetic Parameters in Nucleic Acid Bases: A Theoretical Investigation

SONG Ben-teng1,2, CHU Yue-ying2, WANG Ji-qing1, ZHENG An-min2, DENG Feng2   

  1. 1. Hunan Key Laboratory of Green-Packaging and Application of Biological Nanotechnology, Hunan University of Technology, Zhuzhou 412008, China;
    2. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences), Wuhan 430071, China
  • Received:2015-09-22 Revised:2016-07-12 Online:2016-09-05 Published:2016-09-05

摘要:

通过高精度量子化学理论计算的方法研究了分子间弱的非键相互作用对胸腺嘧啶、尿嘧啶、胞嘧啶和鸟嘌呤四种核酸碱基中17O核的屏蔽张量(σO)和四极耦合常数(QCC)的影响.计算结果表明分子间强的氢键作用以及弱的范德华(vdW)相互作用都对17O核的化学位移(dO)具有较大的影响.随着分子间氢键作用的逐渐增强,dO逐渐减小,当采用包含所有弱相互作用的周期性模型进行计算时,理论结果与实验值吻合.进一步的电荷分析显示,17O核化学位移的减小主要是由于分子间氢键作用强度增加导致17O原子的负电荷密度逐渐增加.此外,计算结果表明碱基中分子间氢键网络和弱的范德华作用对碱基17O QCC也具有显著的影响.周期性模型下,碱基上氧原子的局域结构环境得到平衡,17O QCC达到最小值,与实验结果最为接近.以核酸碱基为例,说明了分子间的氢键网络以及分子间弱的相互作用对于准确计算生物样品的核磁共振(NMR)参数非常重要,以小的团簇模型来计算生物体系的核磁参数将会产生较大的偏差.

关键词: 核磁共振(NMR), 屏蔽张量, 量子化学计算, 核酸碱基, 四极耦合常数

Abstract:

The influence of hydrogen bonding on the shielding tensors and quadrupole coupling constant (QCC) of oxygen atoms in [17O-2] thymine, [17O-4] thymine, [17O-2] uracil, [17O-4] uracil, [17O-2] cytosine, and [17O-6] guanine monohydrate has been studied by high quality quantum chemical calculations with different cluster models. The results showed that both hydrogen bonding and van der Waals (vdW) interactions are crucial for accurate prediction of isotropic 17O chemical shifts (dO). In addition, experimentally measured 17O chemical shifts in these bases decrease with the increase of intermolecular hydrogen bonding interactions, and such interactions need to be accounted for in the theoretical models in order to obtain satisfactory calculated results. Relative to that of dO, the calculation of 17O shielding tensors (d11, d22 and d33) are even more model-dependent. NMR parameters calculated by periodic structure models taking all hydrogen bonding interactions and non-bonding vdW interactions into account were found to be in good agreement with the experimental results. Further analysis revealed that intermolecular hydrogen bonding-induced decrease of dO is mainly due to the increase of 17O negative charge density coming from the carboxyl (C=O) carbon. Furthermore, it was found that hydrogen bonding and weak interaction have remarkable effects on calculated 17O quadrupole coupling constant (QCC) as well. In conclusion, it is essential to take intermolecular hydrogen bonding and weak interactions into accounts in theoretical calculations in order to predict NMR parameters of biological samples correctly.

Key words: NMR, shielding tensor, quantum chemical calculation, nucleic acid bases, quadrupole coupling constant

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