title: Excited-State Dynamics of Oxyluciferin in Firefly Luciferase.
abstract: The color variations of light emitted by some natural and mutant luciferases are normally attributed to collective factors referred to as microenvironment effects; however, the exact nature of these interactions between the emitting molecule (oxyluciferin) and the active site remains elusive. Although model studies of noncomplexed oxyluciferin and its variants have greatly advanced the understanding of its photochemistry, extrapolation of the conclusions to the real system requires assumptions about the polarity and proticity of the active site. To decipher the intricate excited-state dynamics, global and target analysis is performed here for the first time on the steady-state and time-resolved spectra of firefly oxyluciferin complexed with luciferase from the Japanese firefly (Luciola cruciata). The experimental steady-state and time-resolved luminescence spectra of the oxyluciferin/luciferase complex in solution are compared with the broadband time-resolved firefly bioluminescence recorded in vivo. The results demonstrate that de-excitation of the luminophore results in a complex cascade of photoinduced proton transfer processes and can be interpreted by the pH dependence of the emitted light. It is confirmed that proton transfer is the central event in the spectrochemistry of this system for which any assignment of the pH-dependent emission to a single chemical species would be an oversimplification.
authors.affiliation: Faculty of Sciences, Department of Physics and Astronomy, VU University Amsterdam , 1081 HV Amsterdam, The Netherlands.
authors.forename: Joris J
authors.identifier: 0000-0002-1428-0221
authors.initials: JJ
authors.lastname: Snellenburg
authors.affiliation: School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, United Kingdom.
authors.forename: Sergey P
authors.initials: SP
authors.lastname: Laptenok
authors.affiliation: Olis, Inc. , 130 Conway Drive, Bogart, Georgia 30622, United States.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: DeSa
authors.affiliation: New York University Abu Dhabi , P.O. Box 129188, Abu Dhabi, United Arab Emirates.
authors.forename: Panče
authors.identifier: 0000-0003-2416-6569
authors.initials: P
authors.lastname: Naumov
authors.affiliation: Olis, Inc. , 130 Conway Drive, Bogart, Georgia 30622, United States.|School of Chemistry and Biochemistry, Georgia Institute of Technology , 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States.
authors.forename: Kyril M
authors.initials: KM
authors.lastname: Solntsev
mesh_terms: D020134:Catalytic Domain; D007211:Indoles / Q000737:chemistry* / Q000378:metabolism*; D049409:Luciferases, Firefly / Q000378:metabolism*; D008958:Models, Molecular; D011719:Pyrazines / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D007211:Indoles; D011719:Pyrazines; C014730:oxyluciferin; D049409:Luciferases, Firefly