Dencher N A, Sass H J, Büldt G
Technische Universität Darmstadt, Institute of Biochemistry, Physical Biochemistry, Petersenstrasse 22, D-64287 Darmstadt, Germany.
Biochim Biophys Acta. 2000 Aug 30;1460(1):192-203. doi: 10.1016/s0005-2728(00)00139-0.
A wealth of information has been gathered during the past decades that water molecules do play an important role in the structure, dynamics, and function of bacteriorhodopsin (bR) and purple membrane. Light-induced structural alterations in bR as detected by X-ray and neutron diffraction at low and high resolution are discussed in relationship to the mechanism of proton pumping. The analysis of high resolution intermediate structures revealed photon-induced rearrangements of water molecules and hydrogen bonds concomitant with conformational changes in the chromophore and the protein. These observations led to an understanding of key features of the pumping mechanism, especially the vectoriality and the different modes of proton translocation in the proton release and uptake domain of bR. In addition, water molecules influence the function of bR via equilibrium fluctuations, which must occur with adequate amplitude so that energy barriers between conformational states can be overcome.
在过去几十年里，人们已经收集了大量信息，表明水分子在细菌视紫红质（bR）和紫膜的结构、动力学及功能中确实发挥着重要作用。本文讨论了通过X射线和中子衍射在低分辨率和高分辨率下检测到的bR中光诱导的结构变化与质子泵浦机制的关系。对高分辨率中间结构的分析揭示了光子诱导的水分子和氢键重排，同时伴随着发色团和蛋白质的构象变化。这些观察结果有助于理解泵浦机制的关键特征，特别是bR质子释放和摄取域中质子转运的方向性和不同模式。此外，水分子通过平衡涨落影响bR的功能，这种涨落必须具有足够的幅度，以便能够克服构象状态之间的能量障碍。
