Sequence-dependent charge transfer in donor-DNA-acceptor systems: A theoretical study

Abstract

We have theoretically studied charge transfer in donor–DNA–acceptor systems by using a quantum mechanical model based on the tight-binding approach and by applying the Miller–Abrahams model of incoherent hopping model. According to the quantum mechanical model, the rate for charge transfer through DNA bridges consisting of adenine–thymine (AT) base pairs decreases with the bridge length almost exponentially with a falloff parameter β. The value of β was found to increase with the energy difference between the donor and the AT base pairs on the bridge. This behavior allows us to reproduce both weak and strong variations of the transfer rate with the bridge length as found in different experiments. The quantum mechanical model also reproduces the observed increase of the charge-transfer rate due to exchange of AT base pairs on the DNA bridge by guanine–cytosine (GC) base pairs. In contrast, the Miller–Abrahams model of hopping is unable to reproduce the experimentally observed trends. Therefore we conclude that the latter model is not applicable to the description of charge transfer in the systems investigated. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 1009–1016, 1999