Hydrodynamic Collective Effects of Active Protein Machines in Solution and Lipid Bilayers

TL;DR

This paper investigates how active proteins in solutions and lipid bilayers induce hydrodynamic flows that significantly enhance passive particle diffusion and cause chemotaxis-like drift, revealing non-equilibrium transport phenomena.

Contribution

It demonstrates the substantial impact of hydrodynamic flows from active proteins on passive particle dynamics in biological systems, highlighting nonlocal effects in membranes.

Findings

Passive particle diffusion is substantially enhanced by active proteins.

Gradients of active proteins induce chemotaxis-like drift of passive particles.

Active inclusions in membranes contribute to nonlocal diffusion enhancement.

Abstract

The cytoplasm and biomembranes in biological cells contain large numbers of proteins that cyclically change their shapes. They are molecular machines that can function as molecular motors or carry out many other tasks in the cell. We analyze the effects that hydrodynamic flows induced by active proteins have on other passive molecules in solution or membranes. We show that the diffusion constants of passive particles are enhanced substantially. Furthermore, when gradients of active proteins are present, a chemotaxis-like drift of passive particles takes place. In lipid bilayers, the effects are strongly nonlocal, so that active inclusions in the membrane contribute to diffusion enhancement and the drift. The results indicate that the transport properties of passive particles in systems containing active proteins machines operating under nonequilibrium conditions differ from their counterparts in systems at thermal equilibrium.