Localization of positive charge in DNA induced by its interaction with environment

TL;DR

This paper investigates the microscopic mechanisms of positive charge transfer in DNA, showing that environmental interactions dominate over pi-stacking, leading to charge localization and insulating behavior in DNA sequences.

Contribution

The study demonstrates that charge localization in DNA is primarily due to environmental interactions, challenging the assumption of delocalized charge transfer in molecular conductors.

Findings

Charge is localized within a single G site in DNA.

DNA behaves more like an insulator than a conductor.

Experimental verification via charge transfer reactions is suggested.

Abstract

Microscopic mechanisms of positive charge transfer in DNA remain unclear. A quantum state of electron hole in DNA is determined by the competition of the pi-stacking interaction $b$ sharing a charge between different base pairs and the interaction $\lambda$ with the local environment which attempts to trap charge. To determine which interaction dominates we investigated charge quantum states in various $(GC)_{n}$ sequences choosing DNA parameters satisfying experimental data for the balance of charge transfer rates $G^{+} \leftrightarrow G_{n}^{+}$, $n=2,3$ \cite{FredMain}. We show that experimental data can be consistent with theory only assuming $b\ll \lambda$ meaning that charge is typically localized within the single $G$ site. Consequently any DNA sequence including the one consisting of identical base pairs behaves more like an insulating material then a molecular conductor. Our theory can be verified experimentally, for instance measuring balance of charge transfer reactions $G^{+} \leftrightarrow G_{n}^{+}$, $n \geq 4$ and comparing the experimental results with our predictions.