On the Deactivation Mechanisms of Adenine-Thymine Base Pair
2012 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 116, no 13, 4089-4097 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2012. Vol. 116, no 13, 4089-4097 p.
IdentifiersURN: urn:nbn:se:uu:diva-173628DOI: 10.1021/jp300583hISI: 000302337000020OAI: oai:DiVA.org:uu-173628DiVA: diva2:525721