title: Electronic excitations of the green fluorescent protein chromophore in its protonation states: SAC/SAC-CI study.
abstract: Two ground-state protonation forms causing different absorption peaks of the green fluorescent protein chromophore were investigated by the quantum mechanical SAC/SAC-CI method with regard to the excitation energy, fluorescence energy, and ground-state stability. The environmental effect was taken into account by a continuum spherical cavity model. The first excited state, HOMO-LUMO excitation, has the largest transition moment and thus is thought to be the source of the absorption. The neutral and anionic forms were assigned to the protonation states for the experimental A- and B-forms, respectively. The present results support the previous experimental observations.
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Abhijit K
authors.initials: AK
authors.lastname: Das
authors.forename: Jun-Ya
authors.initials: JY
authors.lastname: Hasegawa
authors.forename: Tomoo
authors.initials: T
authors.lastname: Miyahara
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ehara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakatsuji
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D005453:Fluorescence; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000737:chemistry*; D008958:Models, Molecular; D010777:Photochemistry; D011487:Protein Conformation; D037401:Scyphozoa / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins