title: The Effect of Conjugation on the Competition between Internal Conversion and Electron Detachment: A Comparison between Green Fluorescent and Red Kaede Protein Chromophores.
abstract: Kaede, an analogue of green fluorescent protein (GFP), is a green-to-red photoconvertible fluorescent protein used as an in vivo "optical highlighter" in bioimaging. The fluorescence quantum yield of the red Kaede protein is lower than that of GFP, suggesting that increasing the conjugation modifies the electronic relaxation pathway. Using a combination of anion photoelectron spectroscopy and electronic structure calculations, we find that the isolated red Kaede protein chromophore in the gas phase is deprotonated at the imidazole ring, unlike the GFP chromophore that is deprotonated at the phenol ring. We find evidence of an efficient electronic relaxation pathway from higher-lying electronically excited states to the S1state of the red Kaede chromophore that is not accessible in the GFP chromophore. Rapid autodetachment from high-lying vibrational states of S1is found to compete efficiently with internal conversion to the ground electronic state.
authors.affiliation: Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K.
authors.forename: Jamie
authors.initials: J
authors.lastname: Tay
authors.affiliation: Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Parkes
authors.affiliation: School of Chemistry, University of East Anglia , Norwich NR4 7TJ, U.K.
authors.forename: Kiri
authors.initials: K
authors.lastname: Addison
authors.affiliation: School of Chemistry, University of East Anglia , Norwich NR4 7TJ, U.K.
authors.forename: Yohan
authors.initials: Y
authors.lastname: Chan
authors.affiliation: Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K.
authors.forename: Helen C
authors.initials: HC
authors.lastname: Hailes
authors.affiliation: School of Chemistry, University of East Anglia , Norwich NR4 7TJ, U.K.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Bulman Page
authors.affiliation: School of Chemistry, University of East Anglia , Norwich NR4 7TJ, U.K.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Meech
authors.affiliation: Institut de Química Computacional i Catàlisi and Departament de Química, Facultat de Ciències, Universitat de Girona , Campus de Montilivi, C/M. A. Campmany 69, 17003 Girona, Spain.
authors.forename: Lluís
authors.identifier: http://orcid.org/0000-0002-0003-5540
authors.initials: L
authors.lastname: Blancafort
authors.affiliation: Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K.
authors.forename: Helen H
authors.identifier: http://orcid.org/0000-0003-1572-0070
authors.initials: HH
authors.lastname: Fielding