A PROPOSED MODEL FOR ELECTRON CONDUCTION IN DNA-BASED UPON PAIRWISE ANION PI-STACKING - ELECTRON-AFFINITIES AND IONIZATION-POTENTIALS OF THE HYDROGEN-BONDED BASE-PAIRS
Es. Chen et Ecm. Chen, A PROPOSED MODEL FOR ELECTRON CONDUCTION IN DNA-BASED UPON PAIRWISE ANION PI-STACKING - ELECTRON-AFFINITIES AND IONIZATION-POTENTIALS OF THE HYDROGEN-BONDED BASE-PAIRS, Bioelectrochemistry and bioenergetics, 46(1), 1998, pp. 15-19
The values of the electron affinities (EAs) and ionization potentials
(IPs) of the Watson-Crick; hydrogen-bonded base pairs were calculated
using the AM1-multiconfiguration configuration interaction (AM1-MCCI)
method. This procedure was previously used to verify the electron affi
nities of the monomers determined from half wave reduction potentials.
The electron affinities of the DNA base pairs differ by only 180 meV
(4 kcal/mol). This makes rapid electron transport in DNA thermodynamic
ally feasible in biological systems. During anion formation, calculati
ons show geometry changes which affect the noncovalent hydrogen bonds
and pi stacking interactions. A model for rapid electron transfer thro
ugh the pi-system inherent in the base pairs is postulated. This mecha
nism is based upon the separation of the system into two distinct port
ions: a tunneling down the backbone and a pairwise donor-acceptor proc
ess through the pi-way. (C) 1998 Elsevier Science S.A. All rights rese
rved.