Paramagnetic response of muscle-type systems

TL;DR

This paper models muscle-like systems' conformational changes using a paramagnetic Ising model analogy, revealing insights into their collective behavior and limitations of traditional chemo-mechanical descriptions.

Contribution

It reinterprets the Huxley-Simmons model through stochastic dynamics and maps it to a paramagnetic Ising model, highlighting elastic effects and quasi-critical behavior.

Findings

Identification of negative susceptibility in the model

Mapping of muscle conformational changes to a paramagnetic system

Revelation of limitations in conventional chemo-mechanical models

Abstract

We provide a prototypical description of mechanically-induced collective conformational change (folding), relevant in a variety of biological contexts from muscle contraction to hair cell gating and integrin binding. Our study is inspired by the seminal Huxley-Simmons (HS) model which we reinterpret from the perspective of stochastic dynamics involving rigidly coupled bi-stable elements. In this interpretation the HS model can be mapped to a paramagnetic Ising model, however, the equivalence is not complete due to the presence of elastic elements responsible for negative susceptibility and quasi-critical behavior. We go beyond the conventional chemo-mechanical description of such systems, revealing both its strengths and its limitations.