title: pH-Sensitive fluorophores from locked GFP chromophores by a non-alternant analogue of the photochemical meta effect.
abstract: We report the synthesis and characterization of a pH-sensitive fluorescence switch based on a conformationally-locked green fluorescent protein (GFP) chromophore. The chromophore differs from difluoroboryl-locked parent by the addition of a titratable alcohol group on the imidazolinone ring. The chromophore is fluorescent at pH ≤ 5, but becomes non-fluorescent at higher pH, where the substituent is ionized. We use a quantum chemical model to show that the mechanism of the fluorescence turn-off is electronically analogous to photochemical meta effects in aryl-containing systems.
authors.affiliation: School of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072, Australia. seth.olsen@uq.edu.au.
authors.forename: Seth
authors.initials: S
authors.lastname: Olsen
authors.affiliation: Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997 Moscow, Russia and Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russia.
authors.forename: Mikhail S
authors.initials: MS
authors.lastname: Baranov
authors.affiliation: Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997 Moscow, Russia and Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russia.
authors.forename: Nadezhda S
authors.initials: NS
authors.lastname: Baleeva
authors.affiliation: Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997 Moscow, Russia.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Antonova
authors.affiliation: Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX 78712, USA.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Johnson
authors.affiliation: Olis, Inc., 130 Conway Drive, Bogart, GA 30622, USA and School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332-0400, USA. solntsev@gatech.edu.
authors.forename: Kyril M
authors.initials: KM
authors.lastname: Solntsev