title: Tracking of the molecular motion in the primary event of photoinduced reactions of a phytochromobilin model.
abstract: The photoinduced processes of phytochromes have received great research interest for their important biological functions. Phytochromobilin (PΦB), one of the most important phytochrome chromophores, was selected as the prototype to study its photoinduced isomerization. The nonadiabatic dynamics of PΦB 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 PΦB does not display the rotation of the two terminal five-membered rings (ring A and ring D), which is assumed to govern the Pr → Pfr process in the protein. Instead, two S1/S0 conical intersection seams (CI01α and CI01β) characterized by the rotation of the two central rings (ring B and ring C) were proven to play essential roles for the photoisomerization of PΦB in the gas phase. These two conical intersections (CI01α and CI01β) are accessible by the twisting motions of the C9-C10 and C10-C11 bonds, respectively. The CI01α and CI01β 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 → S0 hops.
authors.affiliation: Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao, Shandong 266101, P. R. China.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Zhuang
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Zhenggang
authors.initials: Z
authors.lastname: Lan
mesh_terms: D001664:Biliverdine / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D055668:Photochemical Processes
chemical_list: C075811:phytochromobilin; D001664:Biliverdine