One‐electron redox properties of DNA nucleobases and common tautomers

Abstract

The redox properties of DNA play an influential role in several important processes such as DNA mutation and the interaction of DNA with drugs. Structural changes in DNA nucleobases from its canonical form to its tautomeric forms can alter these properties and may lead to DNA mutation due to altered base-pairing properties. Experimental results for the standard value of DNA redox properties vary due to choice of methodology and solvent. Theoretical determination of these properties is helpful in pinpointing standard values but still vary depending on methodology and chosen experimental benchmark. However, it is of importance to identify the overall trend of electron mobility within DNA while providing reliable standard values for redox reactions. In this work, we present the results of theoretical calculations for redox properties. Using the thermodynamic cycle, we can approximate reliable values. We report the electron affinities, ionization potentials, and redox potential for the canonical DNA nucleobases and their rare tautomers. For each of these properties, we evaluate its overall trend to gain a greater understanding of the role that electron attachment and electron mobility have within the DNA strand. All calculations are computed at the M06-2X/ 6-3111G(d,p) level of theory.

Do Solvated Electrons (eaq–) Reduce DNA Bases? A Gaussian 4 and Density Functional Theory-Molecular Dynamics Study

“…Our values in DMF are in comparatively good agreement with experiment with a MUE (mean unsigned error) of 0.22 V. Using the M06-2X density functional and 6–31++G(d,p) basis set, Lewis et al 50 calculated the E° vs NHE of G, A, C and T in water as -3.31 V, -2.86 V, -2.41 V and -2.31 V with MUE = 0.27 V. Crespo-Hernández et al 51 used gas-phase vertical electron affinities of G, A, C and T calculated at B3LYP/6-311+G(2df,p)//B3LYP/6-31+G* level of theory to estimate the E° vs NHE (G (ca. -3.0 V), A (-2.71 V), C (-2.56 V) and T (-2.32 V)) in acetonitrile (ε = 36.64) with MUE = 0.2 V.…”

Photoinduced Electron Transfer between Psoralens and DNA: Influence of DNA Sequence and Substitution

“…So, to draw conclusions on the photochemistry of psoralens in applications as PUVA therapy, we have to determine which nucleobases are responsible for the electron donation. Since the purine bases are more easily oxidized than the pyrimidine bases, only guanine and adenine need to be considered as donors . The question whether both purines or only guanine (with the lowest oxidation potential) allow for PET has important implications for the mechanism of photoaddition to DNA.…”

“…Since the purine bases are more easily oxidized than the pyrimidine bases, only guanine and adeninen eed to be considered as donors. [13,14] The question whetherb oth purines or only guanine (with the lowest oxidation potential) allow for PET has important implications for the mechanism of photoaddition to DNA. If both purinesq uenched the excited singlet states efficiently,atriplet path for the photoadditionc ould generallyb ee xcluded.…”

Influence of Electron–Holes on DNA Sequence-Specific Mutation Rates

“…These would be affected by the specific base pair and its position within a sequence. Although we generally find the highest hole probabilities on segments with several G:C base pairs in a row, A:T base pairs may have more favorable energetics for creating a mismatch once a specific base becomes oxidized ( Lewis et al. 2014 ).…”