Hydrogen Bond Network of Water around Protein Investigated with Terahertz and Infrared Spectroscopy
Hydrogen Bond Network of Water around Protein Investigated with Terahertz and Infrared Spectroscopy
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DOI：
10.1016/j.bpj.2016.11.011
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发表时间：
2016-12-20
影响因子：
3.4
通讯作者：
Kondo, Naoshi
中科院分区：
文献类型：
--
作者：
Shiraga, Keiichiro;Ogawa, Yuichi;Kondo, Naoshi
水在蛋白质界面的动力学和结构特性的基础上的宽带复介电常数（0.25至400太赫兹）的白蛋白水溶液。我们对0.25和12 THz之间的介电响应的分析首先揭示了具有延迟的再取向动力学的水合水从白蛋白表面延伸出类似于8.5埃（对应于三到四层）。第二，在白蛋白溶质存在下，非氢键水的数量减少，表明蛋白质抑制水氢键网络的断裂。最后，在白蛋白界面的水分子被发现形成一个扭曲的氢键结构，由于蛋白质表面的拓扑和能量的无序。此外，水的分子内O-H伸缩振动（类似于100 THz），这是敏感的氢键环境，指出了一种趋势，即水合水具有更大的人口相比，体相水的强氢键结合的水分子。从这些实验结果中，我们得出结论，在蛋白质界面的“加强”的水氢键动态减慢水的重定向运动，并通过抑制水-水氢键的断裂形成缺陷较少的氢键网络。然而，这种强化的水氢键网络是由异质氢键距离和角度组成的，因此具有结构“扭曲”的特征。''
The dynamical and structural properties of water at protein interfaces were characterized on the basis of the broadband complex dielectric constant (0.25 to 400 THz) of albumin aqueous solutions. Our analysis of the dielectric responses between 0.25 and 12 THz first revealed hydration water with retarded reorientational dynamics extending similar to 8.5 angstrom (corresponding to three to four layers) out from the albumin surface. Second, the number of nonhydrogen-bonded water was decreased in the presence of the albumin solute, indicating protein inhibits the fragmentation of the water hydrogen-bond network. Finally, water molecules at the albumin interface were found to form a distorted hydrogen-bond structure due to topological and energetic disorder of the protein surface. In addition, the intramolecular O-H stretching vibration of water (similar to 100 THz), which is sensitive to hydrogen-bond environment, pointed to a trend that hydration water has a larger population of strongly hydrogen-bonded water molecules compared with that of bulk water. From these experimental results, we concluded that the "strengthened'' water hydrogen bonds at the protein interface dynamically slow down the reorientational motion of water and form the less-defective hydrogen-bond network by inhibiting the fragmentation of water-water hydrogen bonds. Nevertheless, such a strengthened water hydrogen-bond network is composed of heterogeneous hydrogen-bond distances and angles, and thus characterized as structurally "distorted.''