Electronic coupling mediated by stacked [Thymine-Hg-Thymine] base pairs.
Very recently it has been shown that stable metal-mediated base pairs [Thymine-Hg-Thymine] can form in DNA. To estimate the effect of such pairs on the efficiency of charge transfer through DNA, we carry out quantum mechanical calculations of double-stranded pi-stacks GXG, GXXG, and GXXXG, where X = [Thymine-Hg-Thymine] and stacks GT(n)G of canonical base pairs. The charge-transfer efficiency in short duplexes GXG and GTG is found to be similar. However, the donor-acceptor coupling in GXXG and GXXXG is stronger by a factor of 2.5-3.0 than that in GT(n)G (n = 2 and 3), respectively. It is shown that the valence orbitals of Hg atoms do not essentially participate in mediating the electronic coupling for hole transfer; however, they may play an important role in excess electron transfer.
Voityuk
Alexander A
AA
Institució Catalana de Recerca i Estudis Avançats, Institute of Computational Chemistry, Universitat de Girona, 17071 Girona, Spain. alexander.voityuk@icrea.es
D020029:Base Pairing; D004247:DNA / Q000737:chemistry; D004583:Electrons; D008628:Mercury / Q000737:chemistry*; D013941:Thymine / Q000737:chemistry*
D004247:DNA; D008628:Mercury; D013941:Thymine