title: EPR spectroelectrochemical investigation of guanine radical formation and environment effects.
abstract: Guanine radical detection was carried out by a new convenient and efficient method coupling electron paramagnetic resonance spectroscopy and indirect electrooxidation of guanine in different biological environments, from the free nucleotide to several types of DNA substrates. Compared to the widely used photoirradiation method, this method appeared more selective in the choice of the electrochemical mediator. Carried out in presence of a ruthenium mediator and PBN as spin trap, this method revealed two types of EPR spectra depending of the environment of the guanine radical. Both EPR spectra show the trapping of the neutral guanine radical G(-H)(•) obtained after fast deprotonation of the radical cation G(•+). However, they differ by the atom where the trapped radical is centered. This difference highlights the structural dependency of the environment on the nature of the radical formed. This work gave the evidence of an innovative method to detect in situ the guanine radical.
authors: Université de Toulouse/Université Paul Sabatier , Laboratoire des IMRCP, Bat 2R1, 118 route de Narbonne, 31062 Toulouse cedex 09, France.
authors: Clotilde
authors: C
authors: Ribaut
authors: Guillaume
authors: G
authors: Bordeau
authors: Pierre
authors: P
authors: Perio
authors: Karine
authors: K
authors: Reybier
authors: Valérie
authors: V
authors: Sartor
authors: Olivier
authors: O
authors: Reynes
authors: Paul-Louis
authors: PL
authors: Fabre
authors: Nadia
authors: N
authors: Chouini-Lalanne
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry*; D010084:Oxidation-Reduction; D012428:Ruthenium / Q000737:chemistry; D019097:Spin Trapping
chemical_list: D056831:Coordination Complexes; D003497:Cyclic N-Oxides; D005609:Free Radicals; C029217:phenyl-N-tert-butylnitrone; D006147:Guanine; D012428:Ruthenium