Chiral autocatalysis: reaction noise, micro-reversibility and chiral inhibition in mirror symmetry breaking

TL;DR

This paper analyzes the feasibility of spontaneous mirror symmetry breaking in autocatalytic chemical systems, concluding that racemic states are stable under detailed balance constraints, challenging previous assumptions about homochirality origins.

Contribution

It demonstrates that under detailed balance, autocatalytic systems cannot spontaneously break mirror symmetry, emphasizing the need for non-linear heterochiral dynamics for homochirality.

Findings

Racemic state is stable in both deterministic and stochastic models.

Reaction noise does not induce symmetry breaking under detailed balance.

Non-linear heterochiral dynamics are necessary for homochirality.

Abstract

Applying the constraints dictated by the principle of detailed balance, we analyze a recent proposal for spontaneous mirror symmetry breaking (SMSB) based on enantioselective autocatalysis coupled to a linear decay of the enantiomers and in the presence of reaction noise. We find the racemic state is the final stable outcome for both deterministic as well as for stochastic dynamics, and for both well-mixed and small spatially-coupled systems. The racemic outcome results even when the autocatalytic cycles are driven irreversibly by external reagents, in manifestly non-equilibrium conditions. Our findings suggest that first-order autocatalysis coupled to reactions involving \textit{non-linear} heterochiral dynamics is a necessary pre-condition for any mechanism purporting to lead to molecular homochirality.