Mechanism of Absorption Wavelength Shift of Bacteriorhodopsin During Photocycle
Mechanism of Absorption Wavelength Shift of Bacteriorhodopsin During Photocycle
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DOI：
10.1021/acs.jpcb.2c04359
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发表时间：
2022-11-22
影响因子：
3.3
通讯作者：
Ishikita，Hiroshi
中科院分区：
文献类型：
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作者：
Noji，Tomoyasu;Ishikita，Hiroshi
细菌视紫红质是一种光驱动的质子泵，在光循环期间改变410-617 nm范围内的吸收波长。在这里，我们报告的吸收波长，计算使用12个细菌视紫红质晶体结构（包括BR，BR 13-顺式，J，K 0，KE，KL，L，M，N和O状态结构）和一个组合的量子力学/分子力学/极化连续模型（QM/MM/PCM）的方法。QM/MM/PCM计算再现了实验测量的吸收波长，标准偏差为4 nm。吸收波长的移动主要由以下四个因素解释：（i）由蛋白质环境诱导的视网膜席夫碱变形/扭曲，导致蛋白质环境与视网膜席夫碱之间的静电相互作用降低;（ii）蛋白质环境的质子化状态的变化，直接改变蛋白质环境和视网膜席夫碱之间的静电相互作用;（iii）质子化状态的变化;或（iv）网膜席夫碱的异构化，其中异构体的吸收波长最初不同。
Bacteriorhodopsin, a light-driven proton pump, alters the absorption wavelengths in the range of 410–617 nm during the photocycle. Here, we report the absorption wavelengths, calculated using 12 bacteriorhodopsin crystal structures (including the BR, BR13-cis, J, K0, KE, KL, L, M, N, and O state structures) and a combined quantum mechanical/molecular mechanical/polarizable continuum model (QM/MM/PCM) approach. The QM/MM/PCM calculations reproduced the experimentally measured absorption wavelengths with a standard deviation of 4 nm. The shifts in the absorption wavelengths can be explained mainly by the following four factors: (i) retinal Schiff base deformation/twist induced by the protein environment, leading to a decrease in the electrostatic interaction between the protein environment and the retinal Schiff base; (ii) changes in the protonation state of the protein environment, directly altering the electrostatic interaction between the protein environment and the retinal Schiff base; (iii) changes in the protonation state; or (iv) isomerization of the retinal Schiff base, where the absorption wavelengths of the isomers originally differ.