Chemistry Department, Bowling Green State University, Bowling Green, Ohio 43403, United States.
J Am Chem Soc. 2011 Mar 16;133(10):3354-64. doi: 10.1021/ja1056196. Epub 2011 Feb 22.
Rhodopsin (Rh) and bathorhodopsin (bathoRh) quantum-mechanics/molecular-mechanics models based on ab initio multiconfigurational wave functions are employed to look at the light induced π-bond breaking and reconstitution occurring during the Rh → bathoRh and bathoRh → Rh isomerizations. More specifically, semiclassical trajectory computations are used to compare the excited (S(1)) and ground (S(0)) state dynamics characterizing the opposite steps of the Rh/bathoRh photochromic cycle during the first 200 fs following photoexcitation. We show that the information contained in these data provide an unprecedented insight into the sub-picosecond π-bond reconstitution process which is at the basis of the reactivity of the protein embedded 11-cis and all-trans retinal chromophores. More specifically, the data point to the phase and amplitude of the skeletal bond length alternation stretching mode as the key factor switching the chromophore to a bonding state. It is also confirmed/found that the phase and amplitude of the hydrogen-out-of-plane mode controls the stereochemical outcome of the forward and reverse photoisomerizations.
基于从头算多组态波函数的视紫红质（Rh）和视紫红质前体（bathoRh）量子力学/分子力学模型，用于研究光诱导π键断裂和重组，这些过程发生在 Rh→bathoRh 和 bathoRh→Rh 异构化过程中。更具体地说，使用半经典轨迹计算来比较激发态（S(1)）和基态（S(0)）动力学，这些动力学描述了 Rh/bathoRh 光致变色循环相反步骤在光激发后最初 200 fs 内的特征。我们表明，这些数据中包含的信息提供了对亚皮秒 π键重组过程的前所未有的深入了解，该过程是蛋白质嵌入的 11-顺式和全反式视黄醛发色团反应性的基础。更具体地说，数据指向骨架键长交替拉伸模式的相位和幅度是将发色团切换到成键状态的关键因素。还证实/发现，氢出平面模式的相位和幅度控制着正向和反向光致异构化的立体化学结果。
