help button home button Biophys. J.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Originally published as Biophys J. BioFAST on September 8, 2006.
doi:10.1529/biophysj.106.087593
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
biophysj.106.087593v1
91/11/4166    most recent
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Fujimoto, B. S.
Right arrow Articles by Schurr, J. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Fujimoto, B. S.
Right arrow Articles by Schurr, J. M.
Biophysical Journal 91:4166-4179 (2006)
© 2006 The Biophysical Society

Torsional Rigidities of Weakly Strained DNAs

Bryant S. Fujimoto, Gregory P. Brewood and J. Michael Schurr

Department of Chemistry, University of Washington, Seattle, Washington

Correspondence: Address reprint requests to J. Michael Schurr, Dept. of Chemistry, University of Washington, Box 351700, Seattle, WA 98195. Tel.: 206-543-6681; Fax: 206-685-8665; E-mail: schurr{at}chem.washington.edu.

Measurements on unstrained linear and weakly strained large (≥340 bp) circular DNAs yield torsional rigidities in the range C = 170–230 fJ fm. However, larger values, in the range C = 270–420 fJ fm, are typically obtained from measurements on sufficiently small (≤247 bp) circular DNAs, and values in the range C = 300–450 fJ fm are obtained from experiments on linear DNAs under tension. A new method is proposed to estimate torsional rigidities of weakly supercoiled circular DNAs. Monte Carlo simulations of the supercoiling free energies of solution DNAs, and also of the structures of surface-confined supercoiled plasmids, were performed using different trial values of C. The results are compared with experimental measurements of the twist energy parameter, ET, that governs the supercoiling free energy, and also with atomic force microscopy images of surface-confined plasmids. The results clearly demonstrate that C-values in the range 170–230 fJ fm are compatible with experimental observations, whereas values in the range C ≥ 269 fJ fm, are incompatible with those same measurements. These results strongly suggest that the secondary structure of DNA is altered by either sufficient coherent bending strain or sufficient tension so as to enhance its torsional rigidity.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2006 by the Biophysical Society.