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Microscopic Elasticity of DNA from Torsionally-Constrained Stretching

Published online by Cambridge University Press:  15 February 2011

J. D. Moroz  and
P. Nelson
J. D. Moroz
Affiliation:
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
P. Nelson
Affiliation:
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
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Abstract

We investigate the statistical mechanics of a torsionally constrained polymer. The polymer is modelled as an inextensible chain with bend rigidity A, twist rigidity C, and twist-stretch coupling D. In such a model, thermal bend fluctuations couple geometrically to an applied torque through the relation Lk = Tw + Wr. We explore this coupling and find excellent agreement between the predictions of our model and the single λ-DNA molecule stretching experiments of Strick et al. [Science 271 (1996) 1835]. This analysis affords an experimental determination of the microscopic twist rigidity C. Quantitative agreement between theory and experiment is obtained using C = 120 nm and D = 50 nm. The theory further predicts a thermal reduction of the effective twist rigidity induced by bend fluctuations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 489: Symposium K – Materials Science of the Cell , 1997 , 7
Copyright
Copyright © Materials Research Society 1998

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