Strongly hydrogen-bonded water molecules in the Schiff base region of rhodopsins
Strongly hydrogen-bonded water molecules in the Schiff base region of rhodopsins
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DOI：
10.1039/b416698a
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发表时间：
2005-08
影响因子：
3.1
通讯作者：
Y. Furutani;Mikihiro Shibata;H. Kandori
中科院分区：
文献类型：
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作者：
Y. Furutani;Mikihiro Shibata;H. Kandori
在许多视紫红质中，带正电荷的视网膜发色团被带负电荷的羧酸盐稳定，并且通过各种视紫红质的X射线晶体学在席夫碱区域中发现了结合水分子的存在。低温傅里叶变换红外光谱（FTIR）可以直接监测视紫红质内部水分子的氢键变化。特别是，我们发现，一个桥接的水分子之间的席夫碱和Asp85的细菌视紫红质（BR），光驱动的质子泵蛋白，形成了一个非常强的氢键。这可能是一个水合开关的水从Asp85 Asp212在BR的席夫碱区域的质子转移中起着重要的作用。对古菌和视紫红质的研究表明，只有在具有质子泵活性的蛋白质中才存在强氢键水分子。强氢键的水分子和它的瞬态弱化可能是必不可少的质子泵功能的视紫红质。
In many rhodopsins, a positively charged retinal chromophore is stabilized by a negatively charged carboxylate, and the presence of bound water molecules has been found in the Schiff base region by X-ray crystallography of various rhodopsins. Low-temperature Fourier-transform infrared (FTIR) spectroscopy can directly monitor hydrogen-bonding alterations of internal water molecules of rhodopsins. In particular, we found that a bridged water molecule between the Schiff base and Asp85 in bacteriorhodopsin (BR), a light-driven proton-pump protein, forms an extremely strong hydrogen bond. It is likely that a hydration switch of the water from Asp85 to Asp212 plays an important role in the proton transfer in the Schiff base region of BR. Comprehensive studies of archaeal and visual rhodopsins have revealed that strongly hydrogen-bonded water molecules are only found in the proteins exhibiting proton-pump activities. Strongly hydrogen-bonded water molecules and its transient weakening may be essential for the proton-pump function of rhodopsins.