Merz H, Zundel G
Biochem Biophys Res Commun. 1986 Jul 31;138(2):819-25. doi: 10.1016/s0006-291x(86)80570-8.
During the photocycle of bacteriorhodopsin (BR) the chromophore, a retinal Schiff base, is deprotonated. Simultaneously an asp residue is protonated. These results suggest that this deprotonation occurs via a Schiff base - asp hydrogen bond. Therefore, we studied carboxylic acid - retinal Schiff base model systems in CCl4 using IR spectroscopy. The IR spectra show that double minimum proton potentials are present in the OH ... N in equilibrium with O- ... HN+ H-bonds formed and that the proton can easily be shifted in these bonds by local electrical fields. The thermodynamic data of H-bond formation and proton transfer within these H-bonds are determined. On the basis of these data a hypothesis is developed with regard to the molecular mechanism of the deprotonation of the Schiff base of BR.
在细菌视紫红质（BR）的光循环过程中，发色团（一种视黄醛席夫碱）会发生去质子化。同时，一个天冬氨酸残基会被质子化。这些结果表明，这种去质子化是通过席夫碱 - 天冬氨酸氢键发生的。因此，我们使用红外光谱法研究了四氯化碳中的羧酸 - 视黄醛席夫碱模型体系。红外光谱表明，在形成的O-... HN⁺氢键与OH... N处于平衡状态时存在双势阱质子势，并且质子可以通过局部电场在这些键中轻松移动。确定了这些氢键形成和质子转移的热力学数据。基于这些数据，针对BR席夫碱去质子化的分子机制提出了一个假设。
