Can active hydrodynamic fluctuations affect barrier crossing during enzymatic catalysis?

Abstract

The cellular milieu is teeming with biochemical nano-machines whose activity is a strong source of correlated non-thermal fluctuations termed “active noise”. Essential elements of this circuitry are enzymes, catalysts that speed up the rate of metabolic reactions by orders of magnitude, thereby making life possible. Here, we examine the possibility that active noise in the cell, or in vitro, affects enzymatic catalytic rate by accelerating or decelerating the crossing of energy barriers during reaction. Considering hydrodynamic perturbations induced by biochemical activity as a source of active noise, we attempt to evaluate their plausible impact on the enzymatic cycle using a combination of analytic and numerical methods. Our estimate shows that the fast component of the active noise spectrum may enhance the rate of enzymes, by up to 50%, while reactions remain practically unaffected by the slow noise spectrum and are mostly governed by thermal fluctuations. Revisiting the physics of barrier crossing under the influence of active hydrodynamic fluctuations suggests that the biochemical activity of macromolecules such as enzymes is coupled to active noise, with potential impact on metabolic networks in living and artificial systems alike.