Fractal globule as an artificial molecular machine

TL;DR

This paper investigates the dynamic relaxation properties of a fractal globule modeled as an elastic network, revealing its potential as an artificial molecular machine with hierarchical unfolding behavior similar to biological systems.

Contribution

It introduces a novel elastic network model of a fractal globule and demonstrates its slow, hierarchical relaxation dynamics akin to biological molecular machines.

Findings

The slowest relaxation mode is well-separated from others.

The network quickly relaxes to a low-dimensional manifold.

Unfolding occurs as a cascade of equilibrium phase transitions.

Abstract

The relaxation of an elastic network, constructed by a contact map of a fractal (crumpled) polymer globule is investigated. We found that: i) the slowest mode of the network is separated from the rest of the spectrum by a wide gap, and ii) the network quickly relaxes to a low--dimensional (one-dimensional, in our demonstration) manifold spanned by slowest degrees of freedom with a large basin of attraction, and then slowly approaches the equilibrium not escaping this manifold. By these dynamic properties, the fractal globule elastic network is similar to real biological molecular machines, like myosin. We have demonstrated that unfolding of a fractal globule can be described as a cascade of equilibrium phase transitions in a hierarchical system. Unfolding manifests itself in a sequential loss of stability of hierarchical levels with the temperature change.