Depletion effects and loop formation in self-avoiding polymers

TL;DR

This study uses Langevin dynamics to explore how crowding influences the looping behavior of self-avoiding polymers, revealing a complex interplay between depletion attraction and viscous friction that varies with chain length.

Contribution

It provides new insights into the effects of crowding on polymer looping kinetics, highlighting the contrasting roles of depletion attraction and viscous friction for different chain lengths.

Findings

Short chains experience slowed looping due to increased friction.

Longer chains show more frequent and persistent looping due to depletion attraction.

Results have potential implications for understanding chromatin looping in cells.

Abstract

Langevin dynamics is employed to study the looping kinetics of self-avoiding polymers both in ideal and crowded solutions. A rich kinetics results from the competition of two crowding-induced effects: the depletion attraction and the enhanced viscous friction. For short chains, the enhanced friction slows down looping, while, for longer chains, the depletion attraction renders it more frequent and persistent. We discuss the possible relevance of the findings for chromatin looping in living cells.