The adaptation property in non-equilibrium chemical systems

TL;DR

This paper investigates whether adaptation in chemical systems requires active energy consumption or can occur passively, proving that robust adaptation generally needs energy exchange unless specific conditions are met.

Contribution

It demonstrates that passive systems with detailed balance cannot achieve robust adaptation unless certain factorization conditions are satisfied, and shows that energy exchange enables adaptation.

Findings

Passive detailed balance systems cannot achieve robust adaptation without specific conditions.

Robust adaptation is possible in systems that exchange substances with the environment.

Adaptation requires energy exchange unless particular factorization assumptions are met.

Abstract

The goal of this paper is to understand if the property of adaptation, which is a typical property of many biochemical systems, can be achieved only by biological systems that actively consume energy or if it can be achieved also by passive systems. We prove that, unless the conserved quantities of a signalling system satisfy a very specific factorization assumption, adaptation cannot be achieved in a robust manner (i.e. in a stable manner under perturbations of the chemical reaction rates) by systems that satisfy the detailed balance property, hence that are passive, and that do not exchange substances or energy with the environment. We also prove that robust adaptation can be achieved by systems that satisfy the detailed balance property, but exchange substances with the environment.