Protein surface hydration mapped by site-specific mutations
Protein surface hydration mapped by site-specific mutations
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DOI：
10.1073/pnas.0606235103
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发表时间：
2006-09-19
影响因子：
11.1
通讯作者：
Zewail, Ahmed H.
中科院分区：
文献类型：
--
作者：
Qiu, Weihong;Kao, Ya-Ting;Zewail, Ahmed H.
蛋白质表面的水运动是蛋白质结构、稳定性、动力学和功能的基础。通过使用内在色氨酸作为局部光学探针，并具有飞秒分辨率，可以探测水化层中的表面水运动。在这里，我们报告了使用位点特异性突变对葡萄球菌核酸酶表面局部水合动力学的研究。从 WT 和四个相关突变体的这些研究中，它们改变了局部电荷分布和结构，我们能够确定蛋白质侧链对溶剂化的贡献相对较小。我们确定水合的时间尺度为 3-5 ps 和 100-150 ps。前者是近地表水的局部平动/旋转运动的结果；后者是在蛋白质波动的辅助下直接测量表面水合作用。实验上，WT和四个突变体的这些水合动力学也与总动态斯托克斯位移和荧光发射最大值的结果一致，并且与其局部电荷分布和结构相关。我们讨论了蛋白质波动对不稳定水合时间尺度的作用，并建议重新检查最近的分子动力学模拟。
Water motion at protein surfaces is fundamental to protein structure, stability, dynamics, and function. By using intrinsic tryptophans as local optical probes, and with femtosecond resolution, it is possible to probe surface-water motions in the hydration layer. Here, we report our studies of local hydration dynamics at the surface of the enzyme Staphylococcus nuclease using site-specific mutations. From these studies of the WT and four related mutants, which change local charge distribution and structure, we are able to ascertain the contribution to solvation by protein side chains as relatively insignificant. We determined the time scales of hydration to be 3-5 ps and 100-150 ps. The former is the result of local librational/rotational motions of water near the surface; the latter is a direct measure of surface hydration assisted by fluctuations of the protein. Experimentally, these hydration dynamics of the WT and the four mutants are also consistent with results of the total dynamic Stokes shifts and fluorescence emission maxima and are correlated with their local charge distribution and structure. We discuss the role of protein fluctuation on the time scale of labile hydration and suggest reexamination of recent molecular dynamics simulations.