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Issue 10, 2015

Thermodynamics of force-dependent folding and unfolding of small protein and nucleic acid structures

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Abstract

In this paper, we outline the theoretical framework for understanding the equilibrium force-dependent folding and unfolding transitions of protein domains and small nucleic acid structures, both having small rigid folded structures and highly flexible unfolded polymeric chain conformations. A complete statistical description of the state described by the probability function ρξ(n,x), is obtained, where n is an index denoting the structural state, and x is the extension of the molecule. ξ denotes an external constraint applied to the molecule, which is either a constant force or a harmonic spring attached to one end of the molecule. The extension probability distribution regardless of the structural state: Image ID:c5ib00038f-t1.gif, the free energy landscape: −kBT ln(ρξ(x)), and the probability of the states regardless of the extension: Image ID:c5ib00038f-t2.gif, are analyzed using the force-dependent structural transitions of the classic titin I27 domain as an example. The impact of different external constraints is also discussed.

Graphical abstract: Thermodynamics of force-dependent folding and unfolding of small protein and nucleic acid structures

Article information


Submitted
05 Feb 2015
Accepted
12 Mar 2015
First published
12 Mar 2015

This article is Open Access

Integr. Biol., 2015,7, 1154-1160
Article type
Paper

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