The helix--coil transition on the worm--like chain

TL;DR

This paper introduces a modified worm-like chain model incorporating internal helix/coil order parameters, predicting nonlinear elastic responses like buckling in alpha-helical protein domains relevant to biochemical regulation.

Contribution

It presents a novel variation of the worm-like chain model that accounts for internal order parameters affecting polymer flexibility and response.

Findings

Alpha-helical domains buckle under torque

Model predicts nonlinear elastic behavior

Implications for allosteric regulation

Abstract

I propose a variation of the standard worm--like chain model to account for internal order parameter (helix/coil) fields on the polymer chain. This internal order parameter field influences polymer conformational statistics by locally modifying the persistence length of the chain. Using this model, I make predictions for the bending and stretching response of an alpha-helical domain of a protein. In particular, I show that alpha-helical protein domains will buckle under applied torque. This highly nonlinear elastic behavior may be important in the understanding of allosteric control of biochemical pathways.