Theoretical Study of the Opsin Shift of Deprotonated Retinal Schiff Base in the Mstate of Bacteriorhodopsin
Theoretical Study of the Opsin Shift of Deprotonated Retinal Schiff Base in the Mstate of Bacteriorhodopsin
复制标题
细菌视紫红质状态下去质子化视网膜希夫碱视蛋白位移的理论研究
DOI：
10.1039/c0cp00361a
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
and J. Hasegawa
中科院分区：
文献类型：
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作者：
K. Fujimoto;K. Asai;and J. Hasegawa
利用量子力学和分子力学（QM/MM）相结合的方法，首次从理论上研究了细菌视紫红质（bR）光循环M态中去质子化希夫碱（DPSB）的视蛋白位移的起源。从QM(sacc - ci)/MM（AMBER99）的结果来看，发色团构象效应是主要因素，而与蛋白质环境的库仑相互作用则有不可忽略的贡献。本研究结果修正了以往的研究结论，为DPSB的视蛋白转移机制提供了新的解释。为了验证计算模型考虑了周围环境的电子极化和电荷再分配效应，将DPSB的QM区域的大小扩大到5-7 Å，使溶液和蛋白质中的激发能分别降低0.08-0.13 eV和0.21-0.26 eV。我们还发现rCAM-B3LYP函数在计算C6-C7扭转势能曲线时显著改善了B3LYP结果。
The origin of the opsin shift, which deprotonated Schiff base (DPSB) shows in the M state of the bacteriorhodopsin (bR) photocycle, was theoretically investigated for the first time using a combined quantum mechanical and molecular mechanical (QM/MM) method. From the QM(SAC-CI)/MM(AMBER99) results, the chromophore conformational effect was found to be the main factor, whereas the Coulombic interaction with the protein environment gave a non-negligible contribution. The present result revised the conclusion drawn by previous studies and provided a new interpretation of the opsin shift mechanism of DPSB. To test the computational models for taking into account the electronic polarization and charge redistribution effects of the surrounding environment, the size of the QM region was expanded up to 5–7 Å from DPSB, which decreased the excitation energies in solution and in protein by 0.08–0.13 eV and 0.21–0.26 eV, respectively. We also found that the rCAM-B3LYP functional significantly improves the B3LYP results when calculating the potential energy curve for the C6–C7 twisting.