Garczarek Florian, Gerwert Klaus
Lehrstuhl für Biophysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
Nature. 2006 Jan 5;439(7072):109-12. doi: 10.1038/nature04231. Epub 2005 Nov 9.
Much progress has been made in our understanding of water molecule reactions on surfaces, proton solvation in gas-phase water clusters and proton transfer through liquids. Compared with our advanced understanding of these physico-chemical systems, much less is known about individual water molecules and their cooperative behaviour in heterogeneous proteins during enzymatic reactions. Here we use time-resolved Fourier transform infrared spectroscopy (trFTIR) and in situ H2(18)O/H2(16)O exchange FTIR to determine how the membrane protein bacteriorhodopsin uses the interplay among strongly hydrogen-bonded water molecules, a water molecule with a dangling hydroxyl group and a protonated water cluster to transfer protons. The precise arrangement of water molecules in the protein matrix results in a controlled Grotthuss proton transfer, in contrast to the random proton migration that occurs in liquid water. Our findings support the emerging paradigm that intraprotein water molecules are as essential for biological functions as amino acids.
在我们对表面水分子反应、气相水团簇中的质子溶剂化以及质子在液体中的转移的理解方面已经取得了很大进展。与我们对这些物理化学系统的深入理解相比，对于酶促反应过程中异质蛋白质中单个水分子及其协同行为的了解要少得多。在这里，我们使用时间分辨傅里叶变换红外光谱（trFTIR）和原位H2(18)O/H2(16)O交换FTIR来确定膜蛋白细菌视紫红质如何利用强氢键结合的水分子、具有悬垂羟基的水分子和质子化水团簇之间的相互作用来转移质子。与液态水中发生的随机质子迁移相反，蛋白质基质中水分子的精确排列导致了可控的Grotthuss质子转移。我们的研究结果支持了一种新出现的范式，即蛋白质内的水分子对于生物学功能与氨基酸同样重要。
