In this conference we will present our most recent results on the study of the double proton transfer (DPT) mechanism in the adenine-thymine (AT) and guanine-cytosine (GC) DNA base pairs, both in gas phase and in solution. The condensate phase study was modeled using the polarizable continuum method (PCM) in different solvents. According to our DFT calculations, the DPT may occur for both complexes in a stepwise mechanism in condensate phase, while in gas phase only the GC base pair exhibits a concerted DPT mechanism. Using the Wigner’s tunneling corrections to the transition state theory we show that such corrections are important for the prediction of the rate constants of both systems in gas and in condensate phase. Our results confirm that i) as the polarity of the medium decreases the equilibrium constant of the DPT reaction increases in both complexes, and ii) the equilibrium constant in the GC complex is four orders of magnitude larger than in AT. These observations suggests that spontaneous mutations in DNA are more probable in GC than in AT.

Solvent effect and tunneling corrections on the intermolecular proton transfer of the guanine-cytosine and adenine-thymine DNA base pairs: A polarizable continuum model study

255th National Meeting (2018)

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