Origin, Nature, and Fate of the Fluorescent State of the Green Fluorescent Protein Chromophore at the CASPT2//CASSCF Resolution

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• 作者：Marí ; a Elena Martin ; Fabrizia Negri ; and Massimo Olivucci
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：May 5, 2004
• 年：2004
• 卷：126
• 期：17
• 页码：5452 - 5464
• 全文大小：591K
• 年卷期：v.126,no.17(May 5, 2004)
• ISSN：1520-5126

文摘

Ab initio CASPT2//CASSCF relaxation path computations are employed to determine the intrinsic(e.g., in vacuo) mechanism underlying the rise and decay of the luminescence of the anionic form of thegreen fluorescent protein (GFP) fluorophore. Production and decay of the fluorescent state occur via atwo-mode reaction coordinate. Relaxation along the first (totally symmetric) mode leads to production ofthe fluorescent state that corresponds to a planar species. The second (out-of-plane) mode controls thefluorescent state decay and mainly corresponds to a barrierless twisting of the fluorophore phenyl moiety.While a "space-saving" hula-twist conical intersection decay channel is found to lie only 5 kcal mol^-1 abovethe fluorescent state, the direct involvement of a hula-twist deformation in the decay is not supported byour data. The above results indicate that the ultrafast fluorescence decay observed for the GFP chromophorein solution is likely to have an intrinsic origin. The possible effects of the GFP protein cavity on thefluorescence lifetime of the investigated chromophore model are discussed.