Concerted Asynchronous Hula‐Twist Photoisomerization in the S65T/H148D Mutant of Green Fluorescent Protein |
| |
| Authors: | Dr. Qiangqiang Zhang Prof. Xuebo Chen Dr. Ganglong Cui Prof. Wei‐Hai Fang Prof. Dr. Walter Thiel |
| |
| Affiliation: | 1. Key Laboratory of Theoretical and Computational Photochemistry of the Chinese Ministry of Education, Chemistry College, Beijing Normal University, Beijing 100875 (China);2. Max‐Planck‐Institut für Kohlenforschung, Kaiser‐Wilhelm‐Platz 1, 45470 Mülheim an der Ruhr (Germany) |
| |
| Abstract: | Fluorescence emission of wild‐type green fluorescent protein (GFP) is lost in the S65T mutant, but partly recovered in the S65T/H148D double mutant. These experimental findings are rationalized by a combined quantum mechanics/molecular mechanics (QM/MM) study at the QM(CASPT2//CASSCF)/AMBER level. A barrierless excited‐state proton transfer, which is exclusively driven by the Asp148 residue introduced in the double mutant, is responsible for the ultrafast formation of the anionic fluorescent state, which can be deactivated through a concerted asynchronous hula‐twist photoisomerization. This causes the lower fluorescence quantum yield in S65T/H148D compared to wild‐type GFP. Hydrogen out‐of‐plane motion plays an important role in the deactivation of the S65T/H148D fluorescent state. |
| |
| Keywords: | green fluorescent protein hula‐twist photoisomerization proton transfer QM/MM |
|
|
