Related Experiment Video
Updated: Aug 7, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Asymmetry and free energy transduction in biology
1Laboratory of Molecular Biology, National Institute of Diabetes, and Digestive and Kidney Diseases, Bethesda, MD 20892.
Abstract:
This paper is an extension of our earlier theoretical studies on the relationship between kinetic asymmetry and free-energy transductions in biological systems induced by external fluctuations. In the first part of the paper, the asymmetry conditions necessary for external-noise-induced free-energy transductions to occur are derived for a special cyclic, four-state model in which only one reaction step is perturbed by the fluctuations. The results can be used to explain the earlier findings that asymmetry in rate constants was not required in the uphill transport of ligands induced by externally fluctuating the ligand concentrations. In the second part of the paper, the coupling between two enzyme systems through direct enzyme-enzyme interactions is studied. The existence of kinetic asymmetry in both the driving and the driven enzyme systems is found necessary for coupling and free-energy transduction to occur.
Related Concept Videos
Free Energy
Free Energy and Equilibrium
Recall that Q is the numerical value of the mass action expression...
An Introduction to Free Energy
Free Energy and Equilibrium
The reaction quotient, Q, is a convenient measure of the status of an...
Entropy within the Cell
Membrane Asymmetry Regulating Transporters
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...

