Strong localization of positive charge in DNA induced by its interaction with environment

We investigate a quantum state of positive charge in DNA. A quantum state of electron hole 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 investigate charge quantum states in various (GC)(n) sequences choosing DNA parameters that satisfy experimental data for the balance of charge transfer rates G(+)<-> G(n)(+), n=2,3. We show that experimental data can be consistent with theory only assuming b <lambda, meaning that charge is typically localized within the single G site. Consequently, as follows from our modeling consideration, any DNA duplex including the one consisting of identical base pairs cannot be considered as a molecular conductor. Our theory can be verified experimentally, measuring balance of charge transfer reactions G(+)<-> G(n)(+), n >= 4 and comparing the experimental results with our predictions. (C) 2008 American Institute of Physics.