Inferring the diameter of a biopolymer from its stretching response

TL;DR

This paper develops an analytic model based on stochastic simulations to determine how biopolymer structural features like diameter and granularity influence their stretching response, enabling structural insights from force-extension data.

Contribution

It introduces a new analytic expression linking biopolymer structural parameters to force-extension behavior, validated through extensive simulations and experimental data analysis.

Findings

Recovered elastic parameters consistent with standard models

Estimated biopolymer diameter and granularity from stretching data

Demonstrated structural features significantly impact elastic response

Abstract

We investigate the stretching response of a thick polymer model by means of extensive stochastic simulations. The computational results are synthesized in an analytic expression that characterizes how the force versus elongation curve depends on the polymer structural parameters: its thickness and granularity (spacing of the monomers). The expression is used to analyze experimental data for the stretching of various different types of biopolymers: polypeptides, polysaccharides and nucleic acids. Besides recovering elastic parameters (such as the persistence length) that are consistent with those obtained from standard entropic models, the approach allows to extract viable estimates for the polymers diameter and granularity. This shows that the basic structural polymer features have such a profound impact on the elastic behaviour that they can be recovered with the sole input of stretching measurements.