title: How far can a single hydrogen bond tune the spectral properties of the GFP chromophore?
abstract: Photoabsorption of the hydrogen-bonded complex of a neutral and an anionic Green Fluorescent Protein chromophore has been studied using a new dual-detection approach to action-absorption spectroscopy. Following absorption of one photon, dissociation through a single channel ensures that the full absorption spectrum is measured. Our theoretical account of the spectral shape reveals that the anionic 0-0 transition (464 nm) is blue-shifted compared to that of the wild-type protein (478 nm) due to the stronger H-bond in the dimer, and represents an upper bound for that of the isolated anion. At the same time, the apparent effect of the H-bond for the neutral chromophore is as large as 0.5 eV, red-shifting the absorption maximum of the isolated neutral (340 nm) to that measured in the dimer (393 nm) and various proteins (∼395 nm). This shift results from changes in the topography of potential-energy surfaces in the Franck-Condon region of the H-bonded systems.
authors.affiliation: Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark. lha@phys.au.dk.
authors.forename: Hjalte V
authors.initials: HV
authors.lastname: Kiefer
authors.forename: Elie
authors.initials: E
authors.lastname: Lattouf
authors.forename: Natascha W
authors.initials: NW
authors.lastname: Persen
authors.forename: Anastasia V
authors.initials: AV
authors.lastname: Bochenkova
authors.forename: Lars H
authors.initials: LH
authors.lastname: Andersen
mesh_terms: D019281:Dimerization; D049452:Green Fluorescent Proteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D013057:Spectrum Analysis
chemical_list: D007093:Imidazoles; D049452:Green Fluorescent Proteins