DNA double-helix-mediated long-range electron transfer

✍ Scribed by Satyam Priyadarshy; David N. Beratan; Steven M. Risser

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 503 KB
• Volume: 60
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1996)60:8<1789::aid-qua6>3.0.co;2-u

✦ Synopsis

A theoretical analysis based upon large-scale self-consistent Hartree-Fock calculations at a semiempirical quantum theory level (CNDO/S) is performed to investigate long-range electron transfer in a donor-DNA-acceptor molecule, where the donor and acceptor moieties are tethered to the DNA. The r-stacked base pairs are found to dominate the long-range electronic coupling. Despite the r-electron mediated coypling, the exponential distance decay constant of the electron transfer rate is -1.2-1.6 A-', values typical of electron transfer proteins. The calculated lons-range electron transfer rate of the order of lo6 s-' for a metal-to-metal distance of 21 A is found to be in agreement with kinetic measurements by Meade and Kayyem. Based on the current analysis, the r-electrons dominate the long-range electronic coupling interactions in DNA, but they do not lead to one-dimensional molecular wire-like properties. 0 1996 John Wiley & Sons, Inc.

tions can play a significant role in the ET process. Yet, the structure-property relationships that control these electronic couplings are not well understood in nucleic acids. Questions have been raised in the past about the role of rr and rr-rr stacking interactions in long-range ET, although experimental evidence of rr-electron effects in macromolecule ET has been elusive [6-131. Recently, the study of Murphy et al. [14] suggested an extremely fast electron transfer rate (lo9 S K ' ) for a metal-to-metal distance of > 40 A between partially intercalated * To whom correspondence should be addressed.