Molecular Dynamics Study of the Hydrogen-Bond Kinetics of Protein Hydration Water

水分子驻留在生物分子表面的寿命根据水合位点而变化。是什么决定了生命的多样性？尽管有许多以前的研究，仍然没有统一的图片定量解释这一现象。在这里，我们计算的寿命为一个特定的水合模式，水桥，水桥的寿命从1到~300 ps不等。我们发现它遵循1/k（V_<step>）Pm，其中Pm和V_<step>分别是两个关键因素，即形成一个多个给体原子参与的特定氢键的概率和水化位点的结构波动。这种关系提供了一个图片的氢键动力学与原子的细节，并显示氢键开关发生时，出现一个特定的氢键模式。氢键转换的速率常数k可以被描述为水合位点的结构波动的函数。

The lifetime during which a water molecule resides at the surface of a biomolecule varies according to the hydration site. What determines this variety of lifetimes? Despite many previous studies, there is still no uniform picture quantitatively explaining this phenomenon. Here we calculate the lifetime for a particular hydration pattern, the water bridge, to show that the water-bridge lifetime varies from 1 to ~300 ps. We find that it follows 1/k(V_<step>)Pm, where Pm and V_<step> are two crucial factors, namely the probability of forming a specific hydrogen bond in which more than one donor atom participates, and the structural fluctuation of the hydration site, respectively. This relationship provides a picture of the hydrogen bond kinetics with atomistic detail and shows that hydrogen bond switching occurs when a particular hydrogen-bonding pattern appears. The rate constant of hydrogen bond switching k can be described as a function of the structural fluctuations of the hydration site.