Tracking of the Molecular Motion in the Primary Event of Photoinduced Reactions of a Phytochromobilin Model

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• 作者：Xuhui Zhuang ; Jun Wang ; Zhenggang Lan
• 刊名：Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：December 19, 2013
• 年：2013
• 卷：117
• 期：50
• 页码：15976-15986
• 全文大小：544K
• 年卷期：v.117,no.50(December 19, 2013)
• ISSN：1520-5207

文摘

The photoinduced processes of phytochromes have received great research interest for their important biological functions. Phytochromobilin (P桅B), one of the most important phytochrome chromophores, was selected as the prototype to study its photoinduced isomerization. The nonadiabatic dynamics of P桅B from the Pr configuration in the gas phase was investigated by the surface hopping method at the OM2/MRCI level. In the excited state, isolated P桅B does not display the rotation of the two terminal five-membered rings (ring A and ring D), which is assumed to govern the Pr 鈫?Pfr process in the protein. Instead, two S₁/S₀ conical intersection seams (CI_01伪 and CI_01尾) characterized by the rotation of the two central rings (ring B and ring C) were proven to play essential roles for the photoisomerization of P桅B in the gas phase. These two conical intersections (CI_01伪 and CI_01尾) are accessible by the twisting motions of the C9鈥揅10 and C10鈥揅11 bonds, respectively. The CI_01伪 and CI_01尾 seams, instead of their minimum-energy points, are responsible for the nonadiabatic dynamics. For both channels, the trajectories may propagate forward to the isomerization products or backward to the original Pr configuration after the S₁ 鈫?S₀ hops.