Effects of Molecular Crowding on stretching of polymers in poor solvent

TL;DR

This paper investigates how molecular crowding affects the stretching behavior of polymers in a cellular-like environment, revealing intermediate states, oscillatory force responses, and discontinuous transitions due to disordered surroundings.

Contribution

It introduces a simple model of biopolymer stretching in crowded environments, demonstrating the impact of disorder on transition nature and force-extension characteristics.

Findings

Intermediate states during stretching due to crowding

Oscillations in force-extension curves

Discontinuous transitions with multiple peaks in probability distributions

Abstract

We consider a linear polymer chain in a disordered environment modeled by percolation clusters on a square lattice. The disordered environment is meant to roughly represent molecular crowding as seen in cells. The model may be viewed as the simplest representation of biopolymers in a cell. We show the existence of intermediate states during stretching arising as a consequence of molecular crowding. In the constant distance ensemble the force-extension curves exhibit oscillations. We observe the emergence of two or more peaks in the probability distribution curves signaling the coexistence of different states and indicating that the transition is discontinuous unlike what is observed in the absence of molecular crowding.