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Understanding hydrogenation of the adenine-thymine base pairs and their anions: A density functional study



The B3LYP/DZP++ approach has been used to investigate the properties of hydrogenated radicals and anions of adenine-thymine (A-T) base pairs. Our calculations show that the hydrogenated radicals and anions have relatively high stabilities compared with the single adenine and thymine base. The conformations and hydrogen-bond interactions of A-T base pairs have obviously changed once the hydrogen atoms attached to the A-T base pairs and their anion. As for the hydrogenated A-T radicals, all of them exhibit relatively high electron affinities and different hydrogenation properties with respect to their components. The process of the bond formations of (C6)-H (adenine) and (C6)-H (thymine) are the most favorable in energetics. The two hydrogenation channels have the reaction Gibbs free energies (ΔG°) of −51.8 and −54.2 kcal mol−1, respectively. Also, the calculations on the basis of CPCM model imply that the solvent effect plays an important role in the electron attachment and hydrogenation reactions, and can stabilize the hydrogenated A-T anions. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012