Department of Physics Papers

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Journal Article

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We derive the equation of state of DNA under tension that features a loop. Such loops occur transiently during DNA condensation in the presence of multivalent ions or permanently through sliding protein linkers such as condensin. The force-extension relation of such looped-DNA modeled as a wormlike chain is calculated via path integration in the semiclassical limit. This allows us to rigorously determine the high stretching asymptotics. Notably the functional form of the force-extension curve resembles that of straight DNA, yet with a strongly renormalized apparent persistence length. We also present analogous results for DNA under tension with several protein-induced kinks and/or loops. That means that the experimentally extracted single-molecule elasticity does not necessarily only reflect the bare DNA stiffness, but can also contain additional contributions that depend on the overall chain conformation and length.


Suggested Citation:
I.M. Kulić, H. Mohrbach, R. Thaokar and H. Schiessel. (2007). Equation of state of looped DNA. Physical Review E 75, 011913.

© 2007 The American Physical Society

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Date Posted: 18 May 2011

This document has been peer reviewed.