Emergence of homochirality in large molecular systems

The selection of a single molecular handedness, or homochirality across all living matter, is a mystery in the origin of life. Frank’s seminal model showed in the fifties how chiral symmetry breaking can occur in non-equilibrium chemical networks. However, an important shortcoming in this classic model is that it considers a small number of species, while there is no reason for the prebiotic system, in which homochirality first appeared, to have had such a simple composition.
In this work, using random matrix theory, we show that large non-equilibrium reaction networks undergo a generic and robust phase transition towards a homochiral state as a consequence of the fact that they contain a large number of chiral species. We also quantify how abundant are chiral species in the chemical universe of all possible molecules of a given length by data analysis, to determine the caracterstic molecule size beyond which this symmetry breaking could occur easily. Finally, we propose that Frank’s model should be extended to include a large number of species, in order to possess the transition towards homochirality as confirmed by numerical simulations.

Ref : Laurent G., Lacoste D. and Gaspard P. (PNAS, in review) Emergence of homochirality in large molecular systems