Mechanically induced helix-coil transition in biopolymer networks

TL;DR

This study investigates how applying stress to biopolymer networks induces a non-monotonic helix-coil transition, revealing a mechanically stimulated conformational change consistent with theoretical models.

Contribution

It demonstrates the first experimental observation of mechanically induced helix-coil transition in biopolymer networks and explores its dependence on network properties.

Findings

Helical fraction varies non-monotonically with chain extension.

Transition from coiled to helical structures occurs under stress.

The effect depends on crosslink density and network aging.

Abstract

The quasi-equilibrium evolution of the helical fraction occurring in a biopolymer network (gelatin gel) under an applied stress has been investigated by observing modulation in its optical activity. Its variation with the imposed chain extension is distinctly non-monotonic and corresponds to the transition of initially coiled strands to induced left-handed helices. The experimental results are in qualitative agreement with theoretical predictions of helices induced on chain extension. This new effect of mechanically stimulated helix-coil transition has been studied further as a function of the elastic properties of the polymer network: crosslink density and network aging.