Effects of Intense Electric Fields on the Double Proton Transfer in the Watson–Crick Guanine–Cytosine Base Pair

• Published in: The journal of physical chemistry. B Vol. 122; no. 37; pp. 8631 - 8641
• Main Authors: Arabi, Alya A, Matta, Chérif F
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 20-09-2018
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/acs.jpcb.8b05053

The double proton transfer reaction in the guanine–cytosine (GC) base pair is studied, using density functional theory, to understand the chances of mutations under the effect of uniform electric fields in the order of 108 to 109 V m–1. On the basis of potential energy surfaces, reaction Gibbs energies, equilibrium constants, imaginary frequencies, forward and reverse barrier heights, tunneling-corrected rate constants, half-lives of the forward and reverse reactions, percent tautomerization, and Boltzmann distributions, it was found that fields ≥+3.60 × 109 V m–1 facilitate the mutation in the GC base pair and reduce the rectification of point mutations. Fields applied along the double proton transfer in the −x (defined in the C to G direction) direction favor the canonical over the rare tautomers. Tunneling-corrected rate constants of the forward reaction increase exponentially with stronger fields in the −x direction and follow a Gaussian curve for the reverse reaction.