Connecting Non-Gaussian Water Density Fluctuations to the Lengthscale Dependent Crossover in Hydrophobic Hydration
Connecting Non-Gaussian Water Density Fluctuations to the Lengthscale Dependent Crossover in Hydrophobic Hydration
复制标题
将非高斯水密度波动与疏水水合中的长度尺度相关交叉联系起来
DOI：
10.1021/acs.jpcb.2c04990
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Garde, Shekhar
中科院分区：
文献类型：
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作者：
Sinha, Imee;Cramer, Steven M.;Ashbaugh, Henry S.;Garde, Shekhar
我们连接密度波动在液态水的长度尺度依赖的交叉疏水水化。具体来说，我们采用间接伞采样（INDUS）模拟来表征密度波动的观测体积的各种大小和形状的水，并作为温度和盐浓度的函数。与以前的观察结果一致，密度波动在小分子尺度体积中是高斯的，但在较大的体积中显示非高斯的“低密度脂肪尾巴”。这些非高斯尾部指示水接近其液体到蒸气的相变，并且对生物分子相互作用和功能具有影响。我们发现，发病的非高斯波动在大体积是伴随着形成一个空腔中的观察体积。我们开发了一个模型，使用物理学的腔-水界面形成的一个关键因素，并表明它捕获的非高斯密度波动在水和盐溶液中的广泛区域的性质。我们讨论了这个模型的局限性，在非常低的密度区域的分布。我们的计算提供了新的见解的起源非高斯密度波动的水和它们的连接到长度尺度依赖的交叉在疏水水化。
We connect density fluctuations in liquid water to lengthscale dependent crossover in hydrophobic hydration. Specifically, we employ indirect umbrella sampling (INDUS) simulations to characterize density fluctuations in observation volumes of various sizes and shapes in water and as a function of temperature and salt concentration. Consistent with previous observations, density fluctuations are Gaussian in small molecular scale volumes, but they display non-Gaussian “low-density fat tails” in larger volumes. These non-Gaussian tails are indicative of the proximity of water to its liquid to vapor phase transition and have implications on biomolecular interactions and function. We show that the onset of non-Gaussian fluctuations in large volumes is accompanied by the formation of a cavity in the observation volume. We develop a model that uses the physics of cavity-water interface formation as a key ingredient and show that it captures the nature of non-Gaussian density fluctuations over a broad region in water and in salt solutions. We discuss the limitations of this model in the very low density region of the distribution. Our calculations provide new insights into the origins of non-Gaussian density fluctuations in water and their connections to lengthscale dependent crossover in hydrophobic hydration.