Sugihara Minoru, Buss Volker
Department of Physics, University of Duisburg-Essen, 47048 Duisburg, Germany.
Biochemistry. 2008 Dec 30;47(52):13733-5. doi: 10.1021/bi801986p.
The 9-methyl group of retinal is crucial for the photoreaction of rhodopsin. On the basis of the results of QM/MM simulations, we propose that the primary function of the methyl group is not to properly align the chromophore in the ground state, but that it is a prerequisite for the peculiarly twisted and strained chromophore observed in the batho state. With the methyl group firmly anchored in the protein binding pocket the protein, at the cost of the incipient photon energy, manages to increase the strain energy stored in the chromophore by 25%, which may be crucial for driving the subsequent transformations.
视黄醛的9-甲基对于视紫红质的光反应至关重要。基于量子力学/分子力学（QM/MM）模拟结果，我们提出甲基的主要功能并非在基态下使发色团正确排列，而是它是在向红移态中观察到的特别扭曲且应变的发色团的先决条件。随着甲基牢固地锚定在蛋白质结合口袋中，蛋白质以初始光子能量为代价，设法将发色团中储存的应变能增加25%，这对于驱动后续转变可能至关重要。
