The efficiency of driving chemical reactions by a physical non-equilibrium is kinetically controlled

Abstract

An out-of-equilibrium physical environment can drive chemical reactions into thermodynamically unfavorable regimes. Under prebiotic conditions such a coupling between physical and chemical non-equilibria may have enabled the spontaneous emergence of primitive evolutionary processes. Here, we study the coupling efficiency within a theoretical model that is inspired by recent laboratory experiments, but focuses on generic effects arising whenever reactant and product molecules have different transport coefficients in a flow-through system. In our model, the physical non-equilibrium is represented by a drift-diffusion process, which is a valid coarse-grained description for the interplay between thermophoresis and convection, as well as for many other molecular transport processes. As a simple chemical reaction, we consider a reversible dimerization process, which is coupled to the transport process by different drift velocities for monomers and dimers. Within this minimal model, the coupling efficiency between the non-equilibrium transport process and the chemical reaction can be analyzed in all parameter regimes. The analysis shows that the efficiency depends strongly on the Damköhler number, a parameter that measures the relative timescales associated with the transport and reaction kinetics. Our model and results will be useful for a better understanding of the conditions for which non-equilibrium environments can provide a significant driving force for chemical reactions in a prebiotic setting.

Nonequilibrium theory of enzyme chemotaxis and enhanced diffusion

“…Assuming that these are of the same order of magnitude, we further constrain α S to be approximately unity. This is consistent with the interpretation of α S as a version of the Damköhler number [21,22] in the presence of kicks. In Fig.…”

Stability of 2′,3′ and 3′,5′ cyclic nucleotides in formamide and in water: a theoretical insight into the factors controlling the accumulation of nucleic acid building blocks in a prebiotic pool

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Formation mechanism of thermally controlled pH gradients

“…While the local equilibrium assumption is an excellent approximation in the present experimental context, it would be desirable to relax this assumption, in order to be able to apply the presented theoretical framework also to systems with slower chemical reactions. The behavior of such systems depends explicitly on the Damköhler number, a parameter that measures the relative timescales associated with the transport and reaction kinetics 31 . The inverse Damköhler number may serve as a useful expansion parameter to systematically extend the presented theoretical framework.…”