title: Primary role of the chromophore bond length alternation in reversible photoconversion of red fluorescence proteins.
abstract: Rapid photobleaching of fluorescent proteins can limit their use in imaging applications. The underlying kinetics is multi-exponential and strongly depends on the local chromophore environment. The first, reversible, step may be attributed to a rotation around one of the two exocyclic C-C bonds bridging phenol and imidazolinone groups in the chromophore. However it is not clear how the protein environment controls this motion - either by steric hindrances or by modulating the electronic structure of the chromophore through electrostatic interactions. Here we study the first step of the photobleaching kinetics in 13 red fluorescent proteins (RFPs) with different chromophore environment and show that the associated rate strongly correlates with the bond length alternation (BLA) of the two bridge bonds. The sign of the BLA appears to determine which rotation is activated. Our results present experimental evidence for the dominance of electronic effects in the conformational dynamics of the RFP chromophore.
authors.affiliation: Department of Physics, Montana State University, Bozeman, MT 59717, USA. drobizhev@physics.montana.edu
authors.forename: Mikhail
authors.initials: M
authors.lastname: Drobizhev
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Hughes
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Stepanenko
authors.forename: Pawel
authors.initials: P
authors.lastname: Wnuk
authors.forename: Kieran
authors.initials: K
authors.lastname: O'Donnell
authors.forename: J Nathan
authors.initials: JN
authors.lastname: Scott
authors.forename: Patrik R
authors.initials: PR
authors.lastname: Callis
authors.forename: Alexander
authors.initials: A
authors.lastname: Mikhaylov
authors.forename: Leslie
authors.initials: L
authors.lastname: Dokken
authors.forename: Aleksander
authors.initials: A
authors.lastname: Rebane
mesh_terms: D005453:Fluorescence; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007834:Lasers; D008164:Luminescent Proteins / Q000737:chemistry*; D008962:Models, Theoretical; D019800:Phenol / Q000737:chemistry; D038761:Photobleaching; D000097573:Red Fluorescent Protein
chemical_list: D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D019800:Phenol; D000097573:Red Fluorescent Protein