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RESEARCH PRODUCT
On the Deactivation Mechanisms of Adenine–Thymine Base Pair
João Paulo GobboLuis Serrano-andrésDaniel Roca-sanjuánVicenta SauriAntonio Carlos BorinManuela Merchánsubject
Ultraviolet RaysBase pair02 engineering and technology010402 general chemistry01 natural sciencesReference wavechemistry.chemical_compoundQuantum mechanicsMaterials ChemistryComplete active spacePhysical and Theoretical ChemistryPerturbation theoryBase PairingAdenineFunction (mathematics)021001 nanoscience & nanotechnology0104 chemical sciencesSurfaces Coatings and FilmsThymineBIOFLAVONOIDESchemistryProtonsAtomic physics0210 nano-technologyThymineHydrogendescription
In this contribution, the multiconfigurational second-order perturbation theory method based on a complete active space reference wave function (CASSCF/CASPT2) is applied to study all possible single and double proton/hydrogen transfers between the nucleobases in the adenine-thymine (AT) base pair, analyzing the role of excited states with different nature [localized (LE) and charge transfer (CT)], and considering concerted as well as step-wise mechanisms. According to the findings, once the lowest excited states, localized in adenine, are populated during UV irradiation of the Watson-Crick base pair, the proton transfer in the N-O bridge does not require high energy in order to populate a CT state. The latter state will immediately relax toward a crossing with the ground state, which will funnel the system to either the canonical structure or the imino-enol tautomer. The base pair is also capable of repairing itself easily since the imino-enol species is unstable to thermal conversion.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2012-03-15 | The Journal of Physical Chemistry B |