Ab initio molecular dynamics study of glycine intramolecular proton transfer in water.
Ab initio molecular dynamics study of glycine intramolecular proton transfer in water.
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DOI：
10.1063/1.1885445
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发表时间：
2005-03
期刊：
影响因子：
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通讯作者：
K. Leung;S. Rempe
中科院分区：
文献类型：
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作者：
K. Leung;S. Rempe
我们使用从头算分子动力学模拟来量化模型质子转移反应的结构和热力学性质，该反应将在气相中稳定的中性甘氨酸分子转化为在水溶液中占主导地位的两性离子。计算了甘氨酸分子内质子直接转移的平均力势。结构分析表明，甘氨酸的平均水合数（N（w））沿反应坐标不是沿着恒定的，而是从中性分子的N（w）= 5逐渐增加到两性分子的N（w）= 8。我们报道了中性和带电甘氨酸分子之间的自由能差异，以及质子转移的自由能垒。最后，我们确定了我们的方法中固有的近似，并估计相应的修正，我们报告的热力学预测。
We use ab initio molecular-dynamics simulations to quantify structural and thermodynamic properties of a model proton transfer reaction that converts a neutral glycine molecule, stable in the gas phase, to the zwitterion that predominates in aqueous solution. We compute the potential of mean force associated with the direct intramolecular proton transfer event in glycine. Structural analyses show that the average hydration number (N(w)) of glycine is not constant along the reaction coordinate, but rather progresses from N(w) = 5 in the neutral molecule to N(w) = 8 for the zwitterion. We report the free-energy difference between the neutral and charged glycine molecules, and the free-energy barrier to proton transfer. Finally, we identify the approximations inherent in our method and estimate the corresponding corrections to our reported thermodynamic predictions.