Cooperative transitions involving hydrophobic polyelectrolytes

TL;DR

This paper explains the sharp, cooperative conformational transitions of hydrophobic polyelectrolytes involving membrane interactions, using MWC theory, with implications for medicine and switchable materials.

Contribution

It applies MWC theory to describe pH-dependent membrane interactions of hydrophobic polyelectrolytes, revealing conditions for sharp conformational transitions.

Findings

Transitions are governed by competition between conformational states.

Sharp transitions depend on concentration of molecular ligands.

Framework applicable to designing switchable materials.

Abstract

Hydrophobic polyelectrolytes (HPE) can solubilize bilayer membranes, form micelles or can reversibly aggregate as a function of pH. The transitions are often remarkably sharp. We show that these cooperative transitions occur by a competition between two or more conformational states and can be explained within the framework of Monod - Wymann - Changeux (MWC) theory that was originally formulated for allosteric interactions. Here we focus on the pH-dependent destabilization and permeation of bilayer membranes by HPE. We formulate the general conditions that lead to sharp conformational transitions involving simple macromolecules mediated by concentration variations of molecular ligands. That opens up potential applications ranging from medicine to the development of switchable materials.