State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China.
Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
Spectrochim Acta A Mol Biomol Spectrosc. 2017 Mar 5;174:25-31. doi: 10.1016/j.saa.2016.11.015. Epub 2016 Nov 13.
The absorption spectra of bovine rhodopsin mutant E113Q in solutions were investigated at the molecular level by using a hybrid quantum mechanics/molecular mechanics (QM/MM) method. The calculations suggest the mechanism of the absorption variations of E113Q at different pH values. The results indicate that the polarizations of the counterions in the vicinity of Schiff base under protonation and unprotonation states of the mutant E113Q would be a crucial factor to change the energy gap of the retinal to tune the absorption spectra. Glu-181 residue, which is close to the chromophore, cannot serve as the counterion of the protonated Schiff base of E113Q in dark state. Moreover, the results of the absorption maximum in mutant E113Q with the various anions (Cl, Br, I and NO) manifested that the mutant E113Q could have the potential for use as a template of anion biosensors at visible wavelength.
采用混合量子力学/分子力学（QM/MM）方法在分子水平上研究了牛视紫红质突变体 E113Q 在溶液中的吸收光谱。计算结果表明了不同 pH 值下 E113Q 吸收变化的机制。结果表明，在质子化和非质子化状态下，Schiff 碱附近的反离子的极化作用将是改变视黄醛能隙以调节吸收光谱的关键因素。与发色团接近的Glu-181 残基不能作为暗态中 E113Q 质子化 Schiff 碱的抗衡离子。此外，突变体 E113Q 与各种阴离子（Cl、Br、I 和 NO）的吸收最大值的结果表明，突变体 E113Q 有可能作为可见波长阴离子生物传感器的模板。
