title: Excited state structure and dynamics of the neutral and anionic flavin radical revealed by ultrafast transient mid-IR to visible spectroscopy.
abstract: Neutral and anionic flavin radicals are involved in numerous photochemical processes and play an essential part in forming the signaling state of various photoactive flavoproteins such as cryptochromes and BLUF domain proteins. A stable neutral radical flavin has been prepared for study in aqueous solution, and both neutral and anion radical states have been stabilized in the proteins flavodoxin and glucose oxidase. Ultrafast transient absorption measurements were performed in the visible and mid-infrared region in order to characterize the excited state dynamics and the excited and ground state vibrational spectra and to probe the effect of the protein matrix on them. These data are compared with the results of density functional theory calculations. Excited state decay dynamics were found to be a strong function of the protein matrix. The ultrafast electron transfer quenching mechanism of the excited flavin moiety in glucose oxidase is characterized by vibrational spectroscopy. Such data will be critical in the ongoing analysis of the photocycle of photoactive flavoproteins.
authors.affiliation: School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom.
authors.forename: Andras
authors.initials: A
authors.lastname: Lukacs
authors.forename: Rui-Kun
authors.initials: RK
authors.lastname: Zhao
authors.forename: Allison
authors.initials: A
authors.lastname: Haigney
authors.forename: Richard
authors.initials: R
authors.lastname: Brust
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Greetham
authors.forename: Michael
authors.initials: M
authors.lastname: Towrie
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Tonge
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Meech
mesh_terms: D000838:Anions / Q000737:chemistry; D005415:Flavins / Q000737:chemistry*; D005418:Flavodoxin / Q000737:chemistry / Q000378:metabolism; D005609:Free Radicals / Q000737:chemistry*; D005949:Glucose Oxidase / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D010084:Oxidation-Reduction; D013055:Spectrophotometry, Infrared
chemical_list: D000838:Anions; D005415:Flavins; D005418:Flavodoxin; D005609:Free Radicals; D005949:Glucose Oxidase