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

Torsten Fiebig, Chaozhi Wan, Shana O. Kelley, Jacqueline K. Barton, Ahmed H. Zewail*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

80 Scopus citations

Abstract

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 I 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.

Original languageEnglish (US)
Pages (from-to)1187-1192
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume96
Issue number4
DOIs
StatePublished - Feb 16 1999
Externally publishedYes

ASJC Scopus subject areas

  • General

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