title: Role of Coherent Low-Frequency Motion in Excited-State Proton Transfer of Green Fluorescent Protein Studied by Time-Resolved Impulsive Stimulated Raman Spectroscopy.
abstract: Green fluorescent protein (GFP) from jellyfish Aequorea victoria, an essential bioimaging tool, luminesces via excited-state proton transfer (ESPT) in which the phenolic proton of the p-hydroxybenzylideneimidazolinone chromophore is transferred to Glu222 through a hydrogen-bond network. In this process, the ESPT mediated by the low-frequency motion of the chromophore has been proposed. We address this issue using femtosecond time-resolved impulsive stimulated Raman spectroscopy. After coherently exciting low-frequency modes (<300 cm(-1)) in the excited state of GFP, we examined the excited-state structural evolution and the ESPT dynamics within the dephasing time of the low-frequency vibration. A clear anharmonic vibrational coupling is found between one high-frequency mode of the chromophore (phenolic CH bend) and a low-frequency mode at ∼104 cm(-1). However, the data show that this low-frequency motion does not substantially affect the ESPT dynamics.
authors.forename: Tomotsumi
authors.initials: T
authors.lastname: Fujisawa
authors.forename: Hikaru
authors.initials: H
authors.lastname: Kuramochi
authors.affiliation: Department of Biomolecular Science, Faculty of Sciences, Toho University , 2-2-1 Miyama, Funabashi 274-8510, Japan.
authors.forename: Haruko
authors.initials: H
authors.lastname: Hosoi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takeuchi
authors.forename: Tahei
authors.initials: T
authors.lastname: Tahara
mesh_terms: D049452:Green Fluorescent Proteins / Q000737:chemistry*; D011522:Protons; D013059:Spectrum Analysis, Raman
chemical_list: D011522:Protons; D049452:Green Fluorescent Proteins