Long-Distance Electron Transfer Through DNA

DNA molecules are able to transport electrons over long distances. In most experiments the process is stimulated by the oxidation of guanines (G), which generates guanine radical cations. The electron transport through DNA occurs in a multistep hopping mechanism with all Gs as carriers of the positive charge. The rate of each individual hopping step between the Gs decreases strongly with increase of the distance. If the (A:T) bridges between the guanines are long, adenines (A) also become charge carriers. Mismatches, single strands, and G-oxidation products can drastically diminish the efficiency of the charge transport. But in triplexes and DNA/RNA duplexes, as well as in several duplex DNA/peptide complexes, the efficacy of the charge transport is less affected. The ability of DNA molecules to transport charges over long distances could provide a mechanism for ameliorating the harmfulness of damage to DNA under the conditions of oxidative stress.