Distance dependence of electron transfer in acridine-intercalated DNA

Keijiro Fukui, Kazuyoshi Tanaka, Mamoru Fujitsuka, Akira Watanabe, Osamu Ito

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

The photoinduced electron-transfer reaction in a DNA helix has been studied using 9-amino-6-chloro-2-methoxyacridine (ACMA) selectively intercalated at an internucleotide site of a DNA. The photoexcited ACMA is used as an electron acceptor, and guanine in DNA as an electron donor. ACMA-DNA conjugates possessing guanine at 5' or 3' direction(s) with different distance(s) from the intercalated ACMA have been prepared for a systematic examination of the distance dependence of the electron-transfer reaction in a DNA helix. In DNA consisting of only the (dA-dT) base pair, the fluorescence of the singlet-excited ACMA decays in a mono-exponential manner with a longest lifetime of 22.8 ns. The fluorescence lifetime of the excited ACMA decreases with incorporation of guanosine depending on the distance between the ACMA and guanine. When an ACMA and a guanine are directly stacked, the decay lifetime markedly decreases, showing a forward electron-transfer rate, k(fet), of ≃ 1010 s-1. Treating the kinetic data according to k(fet) = Aexp (- βR), where R is the separation distance in Å, gives a β value of 1.47 Å-1. Moreover, as a model compound for ACMA, the redox potential of quinacrine dihydrate bi (tetrafluoroborate) has been measured by cyclic voltammetry in acetonitrile. Comparison of the redox potential with those of nucleobases has revealed that only guanine can quench the fluorescence of ACMA and a free-energy change ΔG°= -0.46 eV has been evaluated for this electron-transfer reaction.

Original languageEnglish
Pages (from-to)18-27
Number of pages10
JournalJournal of Photochemistry and Photobiology B: Biology
Volume50
Issue number1
DOIs
Publication statusPublished - 1999 May 1

Keywords

  • DNA oxidation
  • DNA structures
  • Electron transfer
  • Oligonucleotides
  • π interactions

ASJC Scopus subject areas

  • Radiation
  • Radiological and Ultrasound Technology
  • Biophysics
  • Radiology Nuclear Medicine and imaging

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