title: Light-induced tryptophan radical generation in a click modular assembly of a sensitiser-tryptophan residue.
abstract: Click chemistry was used as an efficient method to covalently attach a chromophore to an amino acid. Such easily prepared model systems allow for time-resolved studies of one-electron oxidation reactions by the excitation of the chromophore by a laser flash. The model complex ruthenium-tryptophan (Ru-Trp) has been synthesised and studied for its photophysical and electrochemical properties. Despite a small driving force of less than 100 meV, excitation with a laser flash results in fast internal electron transfer leading to the formation of the protonated radical (Trp˙H(+)). At neutral pH electron transfer is followed by deprotonation to form the neutral Trp˙ radical with the rate depending on the concentration of water acting as the proton acceptor. The formation of the tryptophan radical was confirmed by EPR.
authors.affiliation: CEA, iBiTec-S, UMR 8221, Service de Bioénergétique Biologie Structurale et Mécanismes (SB2SM), F-91191 Gif-sur-Yvette, France.
authors.forename: Sujitraj
authors.initials: S
authors.lastname: Sheth
authors.forename: Aurélie
authors.initials: A
authors.lastname: Baron
authors.forename: Christian
authors.initials: C
authors.lastname: Herrero
authors.forename: Boris
authors.initials: B
authors.lastname: Vauzeilles
authors.forename: Ally
authors.initials: A
authors.lastname: Aukauloo
authors.forename: Winfried
authors.initials: W
authors.lastname: Leibl
mesh_terms: D057930:Click Chemistry; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D005609:Free Radicals / Q000737:chemistry*; D008027:Light; D010084:Oxidation-Reduction; D011522:Protons; D012428:Ruthenium / Q000737:chemistry*; D014364:Tryptophan / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D005609:Free Radicals; D011522:Protons; D012428:Ruthenium; D014364:Tryptophan