by Andre on 5 January 2008
My latest Physics World news story discusses some recent work on DNA conduction [free signup required to read the whole article]:
Not long after the double-stranded structure of DNA was revealed by Watson and Crick in 1953, scientists suspected that the molecule might support electrical conduction. This is because the bases in the middle of the double helix stack in a way reminiscent of graphite – which is an excellent conductor. At about the same time, the physicist Leon Brillouin suggested that the DNA backbone, rather than the bases, might support conduction because of its periodic structure.
While the conductive properties of DNA have been studied using a wide range of techniques, most experiments have focused on understanding conduction in terms base stacking and have yielded conflicting results. Alternative or complementary conduction mechanisms – such as Brillouin’s backbone conduction – have been largely ignored.
Now there’s been some new experimental work by Hiromi Ikeura-Sekiguchi and Tetsuhiro Sekiguchi that shows that electrons can in fact delocalize through the backbone of DNA as well:
What they found is that electrons in the backbone delocalize in less than one femtosecond (10-15) in wet DNA. These results imply that electron movement occurs a thousand times faster in the DNA backbone than in the bases stacked in the core.
This work is important because it might help to reconcile some of the seemingly contradictory conduction measurements made so far and it might spark some new ideas on re-engineering DNA to improve its electronic properties but what I found most interesting about this field from my background reading for the story are the potential biological implications of DNA conduction.
One interesting possibility is that enzymes communicate through DNA conduction in order to efficiently find sites of DNA damage that need repairing. This idea has been proposed by Jacqueline Barton, one of the people responsible for a resurgence of interest in DNA conduction in the early 1990s. It has also been proposed that DNA conduction could allow cathodic protection of important segments of DNA by transporting holes injected by oxidants to sites where the damage would have a smaller biological impact. This is one of those ideas that has a nice balance of craziness, potential importance, and plausibility. It might even turn out to be true.