Why the Solvation Water around Proteins Is More Dense than Bulk Water
Why the Solvation Water around Proteins Is More Dense than Bulk Water
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DOI：
10.1021/jp305172t
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发表时间：
2012-10-11
影响因子：
3.3
通讯作者：
Zielkiewicz, Jan
中科院分区：
文献类型：
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作者：
Kuffel, Anna;Zielkiewicz, Jan
这项工作的主要目的是对普遍观察到的蛋白质溶剂化壳层内水密度增加的现象提出合理的解释。我们观察到溶剂化层中的水-水氢键网络的几何形状不同于主体水中的氢键网络，它是水分子与蛋白质表面相互作用的结果。网络几何结构的改变反映了溶剂化水结构的变化。我们对观察到的变化的解释是基于Tanaka(Tanaka，H.J.Chem)提出的模型。太棒了。2000、112、799)。根据这个模型，在液态水中，由于水分子具有创建氢键分支网络的独特能力，所以在液态水中存在一些特殊的结构。这些结构具有两个特征：内部相互作用的势能低和比体积大。我们提供了一些证据支持这样的假设，即水-水氢键网络几何形状的变形是这些结构失稳的原因，从而导致水的局部密度增加。我们的模型是基于对某些特定蛋白质的溶剂化水的分析而建立的，这些蛋白质是动蛋白的运动头。随后，我们用它来描述纯疏水表面的溶剂化。已经发现，在这种情况下，疏水表面和邻近的溶剂化层之间存在空闲空间。已经发现，该区域的厚度取决于水-蛋白质界面的局部几何形状，它是水-表面相互作用和水-水相互作用之间保持平衡的结果。在我们看来，这个空间区域的存在是区分疏水水化和天然形式的动蛋白水化的主要因素之一。它的存在也解释了为什么蛋白质天然形式周围的溶剂化水的密度比疏水表面附近的密度大。
The main aim of this work is to propose a rational explanation of the commonly observed phenomenon of increasing water density within solvation shell of proteins. We have observed that the geometry of the water-water hydrogen bond network within solvation layer differs from the one in bulk water, and it is the result of interactions of water molecules with protein surface. Altered geometry of the network reflects changes in the structure of solvation water. Our explanation of the observed changes is based on model proposed by Tanaka (Tanaka, H. J. Chem. Phys. 2000, 112, 799). According to this model, in liquid water exist some special structures formed by water molecules thanks to their unique ability to create the branched network of hydrogen bonds. These structures have two characteristic features: a low potential energy of internal interactions and a large specific volume. We provide some evidence for the supposition that deformation of the geometry of the water-water hydrogen bond network is responsible for destabilization of these structures and therefore for increased local density of water. Our model is constructed on the basis of the analysis of solvation water of some specific protein, the motor head of kinesin. Subsequently, we used it for description of solvation of purely hydrophobic surface. It has been found that in this case an unoccupied space between the hydrophobic surface and neighboring solvation layer exists. It has been found that thickness of this region depends on local geometry of the water-protein interface, and it is a result of maintaining a balance between water-surface interactions and water-water interactions. In our opinion, existence of this space region is one of the main factors that differentiates the hydrophobic hydration from hydration of the native form of kinesin. Its existence also explains why the density is greater for solvation water around the native form of the protein than in the vicinity of the hydrophobic surface.