title: Isomerization in fluorescent protein chromophores involves addition/elimination.
abstract: The green fluorescent protein (GFP) chromophore undergoes both photochemical and thermal isomerizations. Typically, the Z form is more stable and undergoes photochemical conversion to the E form followed by thermal reversion over a period of seconds or minutes. Although the mechanism of the thermal reversion has been the subject of some investigations, the surprisingly low activation energy for this process has not sparked any controversy. We now show that the chromophore is surprisingly stable in both E and Z forms and that the facile thermal reversion is the result of a novel nucleophilic addition/elimination mechanism. This observation may have implications for the intervention of such processes, as well as blinking and kindling, in fluorescent proteins.
authors.affiliation: School of Chemistry and Biochemistry, 901 Atlantic Drive; Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Dong
authors.forename: Fardokht
authors.initials: F
authors.lastname: Abulwerdi
authors.forename: Anthony
authors.initials: A
authors.lastname: Baldridge
authors.forename: Janusz
authors.initials: J
authors.lastname: Kowalik
authors.forename: Kyril M
authors.initials: KM
authors.lastname: Solntsev
authors.forename: Laren M
authors.initials: LM
authors.lastname: Tolbert
mesh_terms: D001593:Benzyl Compounds / Q000737:chemistry*; D049452:Green Fluorescent Proteins / Q000737:chemistry*; D048288:Imidazolines / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D001593:Benzyl Compounds; D048288:Imidazolines; C533767:p-hydroxybenzylidenedimethylimidazolinone; C533768:p-methyletherbenzylidenedimethylimidazolinone; D049452:Green Fluorescent Proteins