蛋白质周围的水动力学：血红蛋白和蜂毒肽的T-和R-状态
Water Dynamics Around Proteins: T- and R-States of Hemoglobin and Melittin
摘要：
研究了四聚血红蛋白和二聚蜂毒肽的水动力学，其特征在于局部疏水性（LH）。对于Hb中的T0到R 0转变，发现LH提供了对Perutz机制的额外分子水平的洞察，即，在α 1/β 2和α 2/β 1界面处盐桥的断裂和形成伴随着LH的变化。对于血红蛋白在立方水箱与90 Aengstroem和120 Aengstroem的边长，它被观察到，在LH减少后，作为一个结果，降低水密度或改变水的取向在蛋白质/水界面的α/β界面是不稳定的，这是一个标志的Perutz立体化学模型的T到R的过渡血红蛋白。因此，目前的工作提供了一个动态视图的经典结构模型相关的Hb功能的分子基础。对于二聚蜂毒肽，Cheng和Rossky（Nature，1998，392，696-699）的早期结果基于来自蛋白质结构被冻结的模拟的LH被证实和解释。对于柔性蜂毒肽二聚体，局部水合的变化可以比刚性二聚体多30%，反映了蛋白质和水动力学耦合的事实。
英文摘要：
The water dynamics, as characterized by the local hydrophobicity (LH), is investigated for tetrameric hemoglobin and dimeric melittin. For the T0 to R0 transition in Hb it is found that LH provides additional molecular-level insight into the Perutz mechanism, i.e., the breaking and formation of salt bridges at the alpha1 / beta2 and alpha2 / beta1 interface is accompanied by changes in LH. For Hb in cubic water boxes with 90 Aengstroem and 120 Aengstroem edge length it is observed that following a decrease in LH as a consequence of reduced water density or change of water orientation at the protein/water interface the alpha / beta interfaces are destabilized; this is a hallmark of the Perutz stereochemical model for the T to R transition in Hb. The present work thus provides a dynamical view of the classical structural model relevant to the molecular foundations of Hb function. For dimeric melittin, earlier results by Cheng and Rossky (Nature, 1998, 392, 696-699) are confirmed and interpreted on the basis of LH from simulations in which the protein structure is frozen. For the flexible melittin dimer the changes in the local hydration can be as much as 30 % than for the rigid dimer, reflecting the fact that protein and water dynamics are coupled.
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