Chemically Modulating the Photophysics of the GFP Chromophore

Jamie Conyard, Minako Kondo, Ismael Heisler, Garth Jones, Anthony Baldridge, Laren M. Tolbert, Kyril M. Solntsev, Steve Meech

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

There is growing interest in engineering the properties of fluorescent proteins through modifications to the chromophore structure utilizing mutagenesis with either natural or unnatural amino acids. This entails an understanding of the photophysical and photochemical properties of the modified chromophore. In this work, a range of GFP chromophores with different alkyl substituents are synthesized and their electronic spectra, pH dependence, and ultrafast fluorescence decay kinetics are investigated. The weakly electron donating character of the alkyl substituents leads to dramatic red shifts in the electronic spectra of the anions, which are accompanied by increased fluorescence decay times. This high sensitivity of electronic structure to substitution is also characteristic of some fluorescent proteins. The solvent viscosity dependence of the decay kinetics are investigated, and found to be consistent with a bimodal radiationless relaxation coordinate. Some substituents are shown to distort the planar structure of the chromophore, which results in a blue shift in the electronic spectra and a strong enhancement of the radiationless decay. The significance of these data for the rational design of novel fluorescent proteins is discussed.
Original languageEnglish
Pages (from-to)1571-1577
Number of pages7
JournalThe Journal of Physical Chemistry B
Volume115
Issue number6
DOIs
Publication statusPublished - 26 Jan 2011

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