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Femtosecond dynamics of the DNA intercalator ethidium and electron transfer with mononucleotides in water

Fiebig, Torsten and Wan, Chaozhi and Kelley, Shana O. and Barton, Jacqueline K. and Zewail, Ahmed H. (1999) Femtosecond dynamics of the DNA intercalator ethidium and electron transfer with mononucleotides in water. Proceedings of the National Academy of Sciences of the United States of America, 96 (4). pp. 1187-1192. ISSN 0027-8424.

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Ethidium (E) is a powerful probe of DNA dynamics and DNA-mediated electron transfer (ET). Molecular dynamical processes, such as solvation and orientation, are important on the time scale of ET. Here, we report studies of the femtosecond and picosecond time-resolved dynamics of E, E with 2'deoxyguanosine triphosphate (GTP) in water, and E with 7-deaza-2'-deoxyguanosine triphosphate (ZTP) in water; E undergoes ET with ZTP but not GTP. These studies elucidate the critical role of relative orientational motions of the donor-acceptor complex on ET processes in solution. For ET from ZTP to E, such motions are in fact the rate-determining step. Our results indicate that these complexes reorient before ET. The time scale for the solvation of E in water is 1 ps, and the orientational relaxation time of E is 70 ps. The impact of orientational and solvation effects on ET between E and mononucleotides must be considered in the application of E as a probe of DNA ET.

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Additional Information:Contributed by Ahmed H. Zewail, December 14, 1998. We thank Chris Treadway for preparing the Eymononucleotide samples and Dr. J. Spencer Baskin for valuable discussions and very helpful comments on the manuscript. We also thank the two referees for their useful suggestions. T.F. is grateful for financial support from the Deutsche Forschungsgemeinschaft. This work was supported by the National Science Foundation. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
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Deposited On:11 Jul 2005
Last Modified:14 Nov 2014 19:18

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