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首页> 外文期刊>RSC Advances >Quantum mechanical calculations of the interactions between diazacrowns and the sodium cation: an insight into Na+ complexation in diazacrown-based synthetic ion channels
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Quantum mechanical calculations of the interactions between diazacrowns and the sodium cation: an insight into Na+ complexation in diazacrown-based synthetic ion channels

机译：量子力学计算，二氮化钠与钠阳离子的相互作用：对达齐齐罗敦合成离子通道中Na +络合的洞察

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摘要

Quantum mechanical calculations were performed to study the conformational behavior and complexation between a sodium cation and a diazacrown (diaza-18-crown-6) using density functional theory (DFT), Moller-Plesset (MP2) and molecular mechanics methods. A goal of this work is to gain a fundamental understanding of the interplay between water molecules, the sodium cation and a diazacrown. Diazacrowns have a significant importance as the functional units of a synthetic sodium channel, called a hydraphile, which functions within a lipid bilayer. This study follows on from our previous classical molecular dynamics study, which investigated the free energy of transport of Na+ as it passes through a lipid bilayer. In the present study we focus on the complexation of Na+, the conformation of the diazacrown and electronic structure that cannot be accessed by classical force fields. Furthermore, we benchmark the force field used in the previous study and make a modification of the dihedral parameters to improve its description. A whole range of configurations are scanned to gain an understanding of the energy landscape and find the minimum energies for configurations involving the diazacrown, diazacrown-Na+, diazacrown-water and diazacrown-Na+-water configurations. Our results show that there is an attractive interaction between Na+ and the oxygen and nitrogen atoms of the diazacrown for which the interaction between Na+ and the oxygen atoms are the stronger of the two. Natural bond orbital (NBO) analysis shows charge-transfer between the diazacrown and Na+ resulting in a reduced positive charge for this cation. This charge transfer occurs directly and via a water-mediated mechanism and could be crucial to the action of the hydraphile sodium channel. Since, in our previous classical molecular dynamics work, it was shown that water molecules accompany Na+ cations as they are transported through a lipid bilayer, while the cations are complexed to the diazacrown moiety of the hydraphile, we aim to better understand the structural, electronic structural and energetic implications of this complexation. Calculations of a water molecule interacting with the diazacrown show that the strongest interaction involves a bridging water molecule that forms hydrogen bonds with two diazacrown oxygen atoms or an oxygen and nitrogen atom on opposite sides of the diazacrown. These interactions may be important in the ordering of water to form a water channel that allows the Na+ to pass through the lipid bilayer.
机译：进行量子力学计算，以研究使用密度泛函理论（DFT），Moller-Plesset（MP2）和分子力学方法研究钠阳离子和二氮化（Diaza-18-Crown-6）之间的构象行为和络合。这项工作的目标是获得对水分子，钠阳离子和二位的相互作用的基本理解。 Diazacrowns作为合成钠通道的功能单元具有重要意义，称为湿法钠通道，其在脂质双层内起作用。本研究遵循我们以前的经典分子动力学研究，该研究研究了Na +的自由能量，因为它通过脂质双层。在本研究中，我们专注于Na +的络合，DiazaCrown和电子结构的构成，可以通过经典力领域进入。此外，我们基准测试前一项研究中使用的力字段，并对Dihedral参数进行修改以改善其描述。扫描整个配置范围以获得对能量景观的理解，并找到涉及DiazaCrown，Diazacrown-Na +，Diazacrown水和Diazacrown-Na + -Water配置的配置的最小能量。我们的研究结果表明，Na +与Diazacrown的氧气和氮原子之间存在含有含有氧的相互作用，其中Na +和氧原子之间的相互作用是两者的较强。天然键（NBO）分析显示Diazacrown和Na +之间的电荷转移，导致该阳离子的阳性电荷降低。该电荷转移直接发生并通过水介导的机制发生，并且对硫酸钠通道的作用至关重要。从我们以前的经典分子动力学工作中，显示出水分子伴随着脂质双层运输的Na +阳离子，而阳离子络合到湿法的Diazacrown部分，我们的目标是更好地了解结构，电子这种综合融合的结构和精力充沛。与DiazaCrown相互作用的水分子的计算表明，最强的相互作用涉及桥接水分子，其在二氮化的两侧形成具有两个二氮杂氧原子或氧气和氮原子的氢键。这些相互作用在水的排序中可能是重要的，以形成允许Na +通过脂质双层的水通道。

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  • 来源
    《RSC Advances》 |2015年第68期|共15页
  • 作者

    Skelton A. A.; Agrawal N.; Fried J. R.;

  • 作者单位

    Univ KwaZulu Natal Sch Hlth Sci Discipline Pharm Durban South Africa;

    Univ KwaZulu Natal Sch Hlth Sci Discipline Pharm Durban South Africa;

    Univ Louisville Chem Engn Louisville KY 40292 USA;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
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