Theory of force-extension curve for modular proteins and DNA hairpins

TL;DR

This paper develops a mesoscopic model for the force-extension behavior of modular biomolecules like proteins and DNA hairpins, incorporating double-well potentials and interactions, and validates it against experimental data.

Contribution

It introduces a comprehensive theoretical framework combining equilibrium and dynamical analyses for modular biomolecules, aligning well with experimental observations.

Findings

Analytical and numerical force-extension curves match experiments

Model captures both equilibrium and dynamical behaviors

Applicable to other metastable systems like superlattices

Abstract

We study a model describing the force-extension curves of modular proteins, nucleic acids, and other biomolecules made out of several single units or modules. At a mesoscopic level of description, the configuration of the system is given by the elongations of each of the units. The system free energy includes a double-well potential for each unit and an elastic nearest neighbor interaction between them. Minimizing the free energy yields the system equilibrium properties whereas its dynamics is given by (overdamped) Langevin equations for the elongations, in which friction and noise amplitude are related by the fluctuation-dissipation theorem. Our results, both for the equilibrium and the dynamical situations, include analytical and numerical descriptions of the system force-extension curves under force or length control, and agree very well with actual experiments in biomolecules. Our conclusions also apply to other physical systems comprising a number of metastable units, such as storage systems or semiconductor superlattices.