On the hydrodynamics of swimming enzymes

TL;DR

This paper proposes a hydrodynamic model explaining enzyme swimming motility during allosteric transitions, challenging previous heat-based explanations and providing new insights into enzyme diffusion enhancement.

Contribution

It introduces a hydrodynamic mechanism for enzyme swimming linked to allosteric transitions, offering an alternative to heat-based explanations for enhanced enzyme diffusion.

Findings

Swimming velocity is estimated during enzyme conformational transitions.

Hydrodynamic size limits the stroke size, smaller than experimental inferences.

Reaction heat effects are ruled out as the primary cause of enhanced diffusion.

Abstract

Several recent experiments suggest that rather generally the diffusion of enzymes may be augmented through their activity. We demonstrate that such swimming motility can emerge from the interplay between the enzyme energy landscape and the hydrodynamic coupling of the enzyme to its environment. Swimming thus occurs during the transit time of a transient allosteric change. We estimate the velocity during the transition. The analysis of such a swimming motion suggests the final stroke size is limited by the hydrodynamic size of the enzyme. This limit is quite a bit smaller than the values that can be inferred from the recent experiments. We also show that one proposed explanation of the experiments based on reaction heat effects can be ruled out using an extended hydrodynamic analysis. These results lead us to propose an alternate explanation of the fluorescence correlation measurements.