title: Electron transfer reactions of fluorotyrosyl radicals.
abstract: The complex Re(bpy)(CO)3CN is an excited state oxidant of tyrosine upon deprotonation of the tyrosyl phenol. A series of Re(bpy-FnY)(CO)3CN complexes ([Re]-FnY: [Re]-Y, [Re]-3-FY, [Re]-3,5-F2Y, [Re]-2,3-F2Y, [Re]-2,3,5-F3Y, [Re]-2,3,6-F3Y, and [Re]-F4Y) have been prepared so as to vary the FnY*/FnY- reduction potential and thus the driving force for electron transfer in this system. Time-resolved emission and nanosecond absorption spectroscopies have been used to measure the rates for charge separation, CS, and charge recombination, CR, for each complex. A driving force analysis reveals that CS is well described by Marcus' theory for ET, is strongly driving force dependent (activated), and occurs in the normal region for ET. CR, on the other hand, is weakly driving force dependent (near activationless) and occurs in the inverted region for ET. These data demonstrate that fluorotyrosines will be powerful probes for unraveling charge transport mechanisms in enzymes that utilize tyrosyl radicals.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: Steven Y
authors.initials: SY
authors.lastname: Reece
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Seyedsayamdost
authors.forename: JoAnne
authors.initials: J
authors.lastname: Stubbe
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Nocera
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry / Q000502:physiology; D002248:Carbon Monoxide / Q000737:chemistry; D004579:Electron Transport; D005609:Free Radicals / Q000737:chemistry*; D007700:Kinetics; D009570:Nitriles / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry; D013057:Spectrum Analysis; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D000596:Amino Acids; D005609:Free Radicals; D009570:Nitriles; D009942:Organometallic Compounds; D016877:Oxidants; C001245:3-fluorotyrosine; D014443:Tyrosine; D015082:2,2'-Dipyridyl; D012211:Rhenium; D002248:Carbon Monoxide