Theoretical and Experimental Study of Charge Transfer through DNA: Impact of Mercury Mediated T-Hg-T Base Pair

Abstract

DNA-Hg complexes may play an important role in sensing DNA defects or in detecting the presence of Hg in the environment. A fundamental way of characterizing DNA-Hg complexes is to study the way the electric charge is transferred through the molecular chain. The main goal of this contribution was to investigate the impact of a mercury metal cation that links two thymine bases in a DNA T-T mismatched base pair (T-Hg-T) on charge transfer through the DNA molecule. We compared the charge transfer efficiencies in standard DNA, DNA with mismatched T-T base pairs, and DNA with a T-Hg(II)-T base pair. For this purpose, we measured the temperature dependence of steady-state fluorescence and UV-vis of the DNA molecules. The experimental results were confronted with the results obtained employing theoretical DFT methods. Generally, the efficiency of charge transfer was driven by mercury changing the spatial overlap of bases.

Application of mercury–mediated thymine–base pairs for successful voltammetric detection of HPV 18

“…The T-T mismatches may have more π-overlapping compared with A-T pairs. The interaction of Hg(II) ions with thymine residues led to increase overlapping, and in consequence the charge transfer was driven by Hg(II) ions [31,32]. In this work, the DNA fragments were attached to the electrode surface via intermediary layer.…”

DNA and RNA Electronic Properties for Molecular Modifications and Environmental State Diagnostics

“…In Kratochvílová et al (2013Kratochvílová et al ( , 2014 and Wagenknecht (2005), fluorescence spectroscopy was used to probe the charge transfer efficiency in DNA/DNA (Fig. 2) duplexes and RNA/DNA hybrids and in DNA/DNA with a mismatched (T-T) base pair and DNA with T-Hg(II)-T (containing the T-T mismatched pair bridged by Hg).…”

“…The decay of the time-resolved fluorescence of photoexcited Ap was fitted in a three- Fig. 2 The chemical structure of a DNA/DNA redox-active duplex for optical spectroscopy measurements-the hole acceptor is guanine and the hole donor is 2-aminopurine (Kratochvílová et al 2013(Kratochvílová et al , 2014. DNA/DNA is composed of two DNA strands, where the donor-acceptor pairs, 2-aminopurine (Ap)-guanine (G), are separated by two or three bases exponential fashion, yielding three lifetimes and three amplitudes.…”

“…The second possible charge transport mechanism in DNA is charge hopping, which presumes localized molecular orbitals and no significant electronic overlap between adjacent base pairs. Unlike (Kratochvílová et al 2014) π-electrons that can form extended molecular orbitals, the DNA backbone, water molecules, and counterions in the solvation shell create localized states resulting in charge conduction by the phonon-assisted (thermally activated) hopping. There is one phenomenon that is important for charge transport in organic molecules: a polaron.…”

RNA and DNA Diagnostics

“…2 The chemical structure of a DNA/DNA redox-active duplex for optical spectroscopy measurements-the hole acceptor is guanine and the hole donor is 2-aminopurine (Kratochvílová et al 2013(Kratochvílová et al , 2014. DNA/DNA is composed of two DNA strands, where the donor-acceptor pairs, 2-aminopurine (Ap)-guanine (G), are separated by two or three bases exponential fashion, yielding three lifetimes and three amplitudes.…”