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Title: Free energy of twisted semiflexible polymers
Authors: Sinha, Supurna
Issue Date: Jun-2008
Publisher: American Physical Society
Citation: Physical Review E, 2008, Vol.77, 061903
Abstract: We investigate the role of fluctuations in single-molecule measurements of torque-link (t-lk) curves. For semiflexible polymers of finite persistence length (i.e., polymers with contour length L comparable to the persistence length LP), the torque versus link curve in the constant-torque (isotorque) ensemble is distinct from the one in the constant-link (isolink) ensemble. Thus, one encounters the conceptually interesting issue of a “free energy of transition” in switching ensembles while making torque-link measurements. We predict the dependence on the semiflexibility parameter beta=L/LP of this extra contribution to the free energy, which shows up as an area in the torque-link plane. This can be tested against future torque-link experiments with single biopolymers. We bring out the inequivalence of torque-link curves for a stiff polymer and present explicit analytical expressions for the distinct torque-link relations in the two ensembles and the free-energy difference in switching ensembles in this context. The predictions of our work can be tested against single-molecule experiments on torsionally constrained biopolymers.
Description: Open Access
ISSN: E-ISSN: 1550-2376
P-ISSN: 1539-3755
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Copyright: 2008 The American Physical Society
Appears in Collections:Research Papers (TP)

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