Electric Dichroism

  • Dietmar Porschke
Part of the Methods in Molecular Biology™ book series (MIMB, volume 90)


Among the methods avallable for the analysis of structures of drug—DNA complexes in solution, the electric dichrolsin is particularly simple, does not require much material, and provtdes information, which cannot be obtained as conveniently by other methods The principle of the electric dichroism is straightforward: electric field pulses are used to align DNA molecules in the direction of the electric field vector, the molecular alignment is analyzed by measurements of the absorbance of polarized light (cf. Fig. 1). One of the advantages of the method is the fact that some important information may already be derived without using any complex theory. In addition, more detailed conclusions may be derived on the basis of appropriate theones, which have been developed up to a rather high degree of sophistication. Three different types of information are available:
  1. 1.

    The direction and the magnitude of the absorbance change induced by the field pulses indicates the orientation of the light-absorbing chromophor with respect to the long axis of the DNA,

  2. 2.

    The time constant(s) of the molecular rotation process indicate(s) the hydrodynamic dimensions of the complex,

  3. 3.

    The electric parameters of the complexes are usually not a target of investigations on drug—DNA complexes and, thus, are not discussed in this contribution Among the books (1, 2, 3, 4) published on the method, the one of Fredericq and Houssler (1) is still the most advisable one for an introduction, although the examples are not up to date.

Fig 1.

Schematic representation of the orientation of rodlike molecules by an external electric field (A) In the absence of an external electric field the molecules are distributed randomly in all directions of space, (B) partial orientation of molecules in the presence of an external electric field, (C) complete orientation in the limit of infinitely high electric field strength


Electric Field Strength Orientation Function Electric Field Pulse Rotational Diffusion Persistence Length 
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  1. 1.
    Fredericq E. and Houssrer C. (1973) Electric dichroism and electric birefringence. Clarendon, Oxford, UKGoogle Scholar
  2. 2.
    O’Konski C. T. (1976) Molecular Electrooptics Part 1 Theory and Methods Marcel Dekker, New YorkGoogle Scholar
  3. 3.
    O’Konski C. T. (1978) Molecular Electrooptics. Part II Applications to blopolymers Marcel Dekker, New York.Google Scholar
  4. 4.
    Stoylov S. P. (1991) Collotd electrooptics. Academic, London.Google Scholar
  5. 5.
    Hogan M., Dattagupta N., and Crothers D. M. (1978) Transient electric dichroism of rod-like DNA molecules. Proc Null Acad Sci USA 75, 195–199CrossRefGoogle Scholar
  6. 6.
    Tirado M. M. and Garcia de la Torre J. (1980) Rotational dynamics of rigid, symmetric top macromolecules Application to circular cylinders. J Chem Phys 73, 1986–1993CrossRefGoogle Scholar
  7. 7.
    Tirado M. M. and Garcia de la Torre J. (1984) Comparison of theories for the translational and rotational diffusion coefficients of rod-like macromolecules. Application to short DNA fragments J Chem Phys 81, 2047–2052CrossRefGoogle Scholar
  8. 8.
    Porschke D. (1996) Analysis of chemical and physical relaxation processes of polyelectrolytes by electric field pulse methods a compartson of critical comments with facts Ber Bunsenges Phys Chem 100, 715–720.CrossRefGoogle Scholar
  9. 9.
    Wegener W. A., Dowben R. M., and Koester V. J. (1979) Time-dependent birefringence, linear dichrotsm, and optical rotation resulting from rigid-body rotational diffuston J Chem Phys 70, 622–632CrossRefGoogle Scholar
  10. 10.
    Colson P., Badly C., and Housster C. (1996) Electic linear dicliroisin as a new tool to study sequence preference in drug binding to DNA Biophys Chem 58, 125–140.CrossRefGoogle Scholar
  11. 11.
    Porschke D. (1989) Electric diclrorsin and bending amplitudes of DNA fragments according to a simple orientation function for weakly bending rods Blopolymers 28, 1383–1396CrossRefGoogle Scholar
  12. 12.
    Grunhagen H. H. (1974) Entwicklung etner E-Feldsprung-Apparatur mit optischer Detektion und ihre Anwendung auf dre Associtation amphlphiler Elektrolyte. Dissertation, Technische Universitat BraunschweigGoogle Scholar
  13. 13.
    Hagerman P. J. (1981) Monte Carlo approach to the analysts of the rotational diffusion of wormlike chains. Biopolymers 20, 148l–1502.Google Scholar
  14. 14.
    Porschke D. and Jung M. (1985) The conformation of single stranded oligo-nucleotides and of oligonucleotide-oligopeptide complexes from then rotation relaxation in the nanosecond time range J Bzomol Struct Dyn 6, 1173–1184CrossRefGoogle Scholar
  15. 15.
    Hogan M., Dattagupta N., and Crothers D. M. (1979) Transtent electric dichrotsm studies of the structure of the DNA complex with intercalated drugs. Biochemistry 18, 280–288.CrossRefGoogle Scholar
  16. 16.
    Norden B., Kubista M., and Kurucsev T. (1992) Linear dicliroisin spectroscopy of nucleic acids Quart Rev Biophys 25, 510–170CrossRefGoogle Scholar
  17. 17.
    Ridler P. J. and Jennings B. R. (1980) Polarized fluorescence studies of electrically oriented DNA-dye solutions. Int J Biol Macromol. 2, 313–317.CrossRefGoogle Scholar
  18. 18.
    Porschke D. and Grell E. (1995) Electric parameters of Na+/K+-ATPase by measurements of the fluorescence-detected electric dichrotsm. Biochzm. Biophys Acta 1231, 181–188Google Scholar

Copyright information

© Humana Press Inc., Totowa, NJ 1997

Authors and Affiliations

  • Dietmar Porschke
    • 1
  1. 1.Max Planck Institut für biophysikalische ChemieGöttingenGermany

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