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Direct Observation of the Torsional Dynamics of DNA and RNA by Picosecond Spectroscopy

Millar, D. P. and Robbins, R. J. and Zewail, A. H. (1980) Direct Observation of the Torsional Dynamics of DNA and RNA by Picosecond Spectroscopy. Proceedings of the National Academy of Sciences of the United States of America, 77 (10). pp. 5593-5597. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:MILpnas80

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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.


Item Type:Article
Additional Information:Copyright © 1980 by the National Academy of Sciences Communicated by R. A. Marcus, July 3, 1980 This work was supported in part by the National Science Foundation under Grant CHE79-05683. A.H.Z. is the recipient of an Alfred P. Sloan Foundation Fellowship and a Camille and Henry Dreyfus Foundation teacher-scholar award. This is contribution no. 6252 from the Division of Chemistry and Chemical Engineering of the California Institute of Technology. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisemment" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Subject Keywords:internal motions of nucleic acids; fluorescence depolarization; ethidium intercalation
Record Number:CaltechAUTHORS:MILpnas80
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:MILpnas80
Alternative URL:http://www.pnas.org/cgi/content/abstract/77/10/5593
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6443
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:09 Dec 2006
Last Modified:26 Dec 2012 09:21

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