EPR Spectroelectrochemical Investigation of Guanine Radical Formation and Environment Effects

Clotilde Ribaut (1) , Guillaume Bordeau (1) , Pierre Pério (2) , Karine Reybier (2) , Valérie Sartor (1) , Olivier Reynes (3) , Paul-Louis Fabre (3) , Nadia Chouini-Lalanne (1)

1 IMRCP - Interactions moléculaires et réactivité chimique et photochimique
2 PHARMA-DEV - Pharmacochimie et Biologie pour le Développement
3 LGC - Laboratoire de Génie Chimique

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.

Mots clés: Guanine radica; Nucleic acids; Genetics; Electron paramagnetic resonance spectroscopy; Guanine; Oxidation

Domaines: Génie chimique; Génie des procédés

Clotilde Ribaut, Guillaume Bordeau, Pierre Pério, Karine Reybier, Valérie Sartor, et al.. EPR Spectroelectrochemical Investigation of Guanine Radical Formation and Environment Effects. Journal of Physical Chemistry B, 2014, 118 (9), pp.2360-2365. ⟨10.1021/jp500952q⟩. ⟨hal-01893395⟩