title: Light driven ultrafast electron transfer in oxidative redding of Green Fluorescent Proteins.
abstract: Fluorescent proteins undergoing green to red (G/R) photoconversion have proved to be potential tools for investigating dynamic processes in living cells and for photo-localization nanoscopy. However, the photochemical reaction during light induced G/R photoconversion of fluorescent proteins remains unclear. Here we report the direct observation of ultrafast time-resolved electron transfer (ET) during the photoexcitation of the fluorescent proteins EGFP and mEos2 in presence of electron acceptor, p-benzoquinone (BQ). Our results show that in the excited state, the neutral EGFP chromophore accepts electrons from an anionic electron donor, Glu222, and G/R photoconversion is facilitated by ET to nearby electron acceptors. By contrast, mEos2 fails to produce the red emitting state in the presence of BQ; ET depletes the excited state configuration en route to the red-emitting fluorophore. These results show that ultrafast ET plays a pivotal role in multiple photoconversion mechanisms and provide a method to modulate the G/R photoconversion process.
authors.affiliation: Unit for Nano Science & Technology, Department of Chemical, Biological & Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata, India.
authors.forename: Ranajay
authors.initials: R
authors.lastname: Saha
authors.forename: Pramod Kumar
authors.initials: PK
authors.lastname: Verma
authors.forename: Surajit
authors.initials: S
authors.lastname: Rakshit
authors.forename: Suvrajit
authors.initials: S
authors.lastname: Saha
authors.forename: Satyajit
authors.initials: S
authors.lastname: Mayor
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Pal
mesh_terms: D016227:Benzoquinones / Q000737:chemistry* / Q000528:radiation effects; D004579:Electron Transport / Q000528:radiation effects; D049452:Green Fluorescent Proteins / Q000737:chemistry* / Q000528:radiation effects*; D008027:Light; D010084:Oxidation-Reduction / Q000528:radiation effects
chemical_list: D016227:Benzoquinones; D049452:Green Fluorescent Proteins; C004532:quinone
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