Department of Chemistry, Ecole Normale Supérieure, 24 rue Lhomond 75005 Paris, France.
J Phys Chem B. 2010 Feb 11;114(5):2083-9. doi: 10.1021/jp9119793.
Water hydrogen-bond (HB) dynamics around amino acids in dilute aqueous solution is investigated through molecular dynamics simulations and analytic modeling. We especially highlight the critical role played by hydrophilic HB acceptors: the strength of the HB formed with water has a pronounced effect on the HB dynamics, in accord with several experimental observations. In contrast, we evidence that hydrophilic HB donors induce a moderate slowdown in the water HB exchange dynamics due to an excluded volume effect, similar to that of hydrophobic groups. We present an analytic model which rationalizes the effect of all examined amino acid sites on the HB dynamics and whose predictions are in excellent agreement with the numerical simulations. This model provides the acceleration or retardation in the HB exchange time with respect to the bulk through the combination of the solute excluded volume factor with the solute-water HB strength factor, both referring to the HB exchange transition state.
通过分子动力学模拟和分析建模研究了稀水溶液中氨基酸周围的水氢键（HB）动力学。我们特别强调了亲水性 HB 受体所起的关键作用：与水形成的 HB 的强度对 HB 动力学有显著影响，这与几项实验观察结果一致。相比之下，我们证明亲水性 HB 供体由于排斥体积效应导致水 HB 交换动力学适度减缓，这与疏水性基团相似。我们提出了一个分析模型，该模型合理地解释了所有被考察的氨基酸位点对 HB 动力学的影响，其预测与数值模拟结果非常吻合。该模型通过将溶质排斥体积因子与溶质-水 HB 强度因子相结合，来预测 HB 交换时间相对于本体的加速或延迟，这两个因子都与 HB 交换过渡态有关。
