Role of Ribophosphate Backbone in Single Molecule DNA Conductance.

This project builds on my long-term effort to understand and describe charge transport in DNA, specifically in DNA that is modified in some way, e.g., by inserting a metal between two DNA bases or DNA damaged by oxidative processes, and is also motivated by the effort to describe charge transport through DNA without the influence of DNA bases. The charge transport mechanism through ribophosphate backbone is probably a secondary mechanism of charge propagation in DNA. As part of the proposed studies, I want to develop a theoretical method describing charge transport that would efficiently incorporate both solvation and conformational and/or dynamical effects influencing charge transport in DNA. The project proposes a combined (experimental-theoretical) fundamental study of charge transport through DNA, specifically DNA containing significant modifications, in this case, oxidized guanine. The aim of the project is to demonstrate whether the conductive characteristics of canonical DNA differ from those of DNA damaged by oxidative processes. For this project, single-stranded DNA molecules terminated at the ends with sulfur-based anchoring groups will be used. In the STM-BJ experiment conducted in water, the DNA will be captured on gold electrodes via these anchoring groups. The experiment will serve to verify a long-discussed issue, namely whether repair enzymes normally present in cells have a chance to use for their recognition the probably different transport characteristics of DNA molecules containing oxidized bases. The STM-BJ method is very suitable for this purpose because it can determine the transport characteristics of individual molecules and the measurements can be performed in water. The measured results will be confronted with theoretical calculations. Within this project, a theoretical method will be tested that allows the inclusion of both solvation and conformational effects and will enable the study of the influence of these important factors on the overall conductivity of DNA.