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RESEARCH PRODUCT
Singlet Oxygen Attack on Guanine: Reactivity and Structural Signature within the B-DNA Helix
Emmanuelle BignonIñaki TuñónElise DumontChristophe MorellRaymond GrüberJean-luc RavanatJuan Arandasubject
0301 basic medicineGuanineBase pairGuanineMolecular Dynamics Simulation010402 general chemistryPhotochemistry01 natural sciencesCatalysis03 medical and health sciencesMolecular dynamicschemistry.chemical_compoundPolydeoxyribonucleotidesReactivity (chemistry)Base PairingSinglet OxygenChemistrySinglet oxygenOrganic ChemistrySolvationGeneral Chemistry0104 chemical sciences030104 developmental biologyCovalent bondHelixDNA B-FormOxidation-Reduction[CHIM.RADIO]Chemical Sciences/Radiochemistrydescription
International audience; Oxidatively generated DNA lesions are numerous and versatile, and have been the subject of intensive research since the discovery of 8-oxoguanine in 1984. Even for this prototypical lesion, the precise mechanism of formation remains elusive due to the inherent difficulties in characterizing high-energy intermediates. We have probed the stability of the guanine endoperoxide in B-DNA as a key intermediate and determined a unique activation free energy of around 6 kcal mol−1 for the formation of the first C−O covalent bond upon the attack of singlet molecular oxygen (1O2) on the central guanine of a solvated 13 base-pair poly(dG-dC), described by means of quantum mechanics/molecular mechanics (QM/MM) simulations. The B-helix remains stable upon oxidation in spite of the bulky character of the guanine endoperoxide. Our modeling study has revealed the nature of the versatile 1O2 attack in terms of free energy and shows a sensitivity to electrostatics and solvation as it involves a charge-separated intermediate.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2016-01-01 |