Direct observation of the torsional dynamics of DNA and RNA by picosecond spectroscopy.
- 1 October 1980
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 77 (10) , 5593-5597
- https://doi.org/10.1073/pnas.77.10.5593
Abstract
Picosecond time-dependent fluorescence depolarization techniques have been used to monitor the reorientation of ethidium bromide intercalated in DNA and RNA. The fluorescence polarization anisotropy reveals a nonexponential, exp(-at 1/2), torsional relaxation of the DNA double helix and provides an accurate value for its torsional rigidity, C = 1.3 +/- 0.2 X 10(-19) erg cm. Furthermore, from accurate measurements of the limiting anisotropy at zero time, we conclude that there is an additional fast (< 10 psec) internal motion that depends on the viscosity of the medium. Denatured DNA is considerably more flexible than the intact double helix, thus demonstrating the influence of secondary structure on internal motions.This publication has 13 references indexed in Scilit:
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