A fluorescent complex between ethidium bromide and nucleic acids: Physical—Chemical characterization,☆☆

https://doi.org/10.1016/0022-2836(67)90353-1Get rights and content

Abstract

At high salt concentrations, ethidium bromide (EB) is shown to form a fluorescent complex with helical polynucleotides which has a strikingly enhanced fluorescence quantum yield. In this paper we present evidence that formation of this complex (complex I) ia specific for base-paired regions either in DNA, RNA or RNA: DNA hybrids, and that the basis of this specificity is intercalation of the dye between base pairs. At low salt concentrations a second mode of binding EB (as complex II) is observed: it appears to be electrostatic binding of the cationic dye to negatively charged phosphate groups. Complex II can be distinguished readily from complex I by its fluorescence properties. The nature of the DNA binding sites for EB has been investigated by: (a) measurement of their number, and dependence of the binding on pH and salt concentration, as well as on the secondary structure and GC content of the DNA; (b) study of the energy transfer from DNA to EB; (c) studies of competition for DNA between EB and Na+, Mg2+, quinacrine and actinomycin, and (d) characterization of complex I by flow dichroism, thermal melting curves and buoyant density.

References (43)

  • R.C. Dryer et al.

    J. Biol. Chem

    (1957)
  • M. Gellert et al.

    J. Mol. Biol

    (1965)
  • F. Hawking
  • H.H. Hiatt

    J. Mol. Biol

    (1962)
  • M. Leng et al.

    J. Mol. Biol

    (1966)
  • J.-B. LePecq et al.

    Biochim. biophys. Acta

    (1966)
  • J.-B. LePecq et al.

    Analyt. Biochem

    (1966)
  • L.S. Lerman

    J. Mol. Biol

    (1961)
  • B.A. Newton
  • C.L. Schildkraut et al.

    J. Mol. Biol

    (1962)
  • C.A. Thomas et al.

    J. Mol. Biol

    (1961)
  • M.J. Waring

    Biochim. biophys. Acta

    (1964)
  • M.J. Waring

    J. Mol. Biol

    (1965)
  • J.S. Wiberg et al.

    Arch. Biochem. Biophys

    (1957)
  • T. Azumi et al.

    J. Chem. Phys

    (1962)
  • K. Burton

    Biochem. J

    (1956)
  • H.B. Clarke et al.

    Biochem. J

    (1954)
  • P. Defrance et al.

    Path. Biol

    (1962)
  • L. Dickinson et al.

    Brit. J. Pharmacol

    (1953)
  • P. Doty et al.
  • W.H. Elliott

    Biochem. J

    (1963)
  • Cited by (2217)

    • Gold(III)-DNA interaction in aqueous solution

      2024, Journal of Molecular Liquids
    View all citing articles on Scopus

    Part of this work (flow dichroism, energy transfer) was done in his laboratory.

    ☆☆

    The research has been supported in part by the Direction des Recherches Moyens et Essais (contract 380/65) and in part by the Délégation générale à la recherche scientifique et technique (contract 61FR060).

    Present address: Department of Biochemistry, Stanford University School of Medicine, Stanford Medical Center, Palo Alto, Calif. 94304, U.S.A.

    View full text