Modulating internal transition kinetics in responsive macromolecules by collective crowding

TL;DR

This study investigates how collective crowding influences the transition kinetics of responsive macromolecules, demonstrating that crowding can significantly modulate switch transition times through a combined theoretical and simulation approach.

Contribution

It introduces a model of responsive colloids with internal size degrees of freedom and derives an exponential scaling law to predict crowding effects on transition kinetics.

Findings

Transition times can be tuned over one order of magnitude by crowding.

An exponential scaling law accurately predicts the effects of crowding.

Simulations agree well with theoretical predictions.

Abstract

Packing and crowding are used in biology as mechanisms to (self-)regulate internal molecular or cellular processes based on collective signalling. Here, we study how the transition kinetics of an internal switch of responsive macromolecules is modified collectively by their spatial packing. We employ Brownian dynamics simulations of a model of responsive colloids (RCs), in which an explicit internal degree of freedom, here, the particle size, moving in a bimodal energy landscape responds self-consistently to the density fluctuations of the crowded environment. We demonstrate that populations and transition times for the two-state switching kinetics can be tuned over one order of magnitude by self-crowding. An exponential scaling law derived from a combination of Kramers' and liquid state perturbation theory is in very good agreement with the simulations.