The Effectivity of Tandem Molecular Machines
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• Physics 16, s56
Machines that encompass two coupled biomolecules commerce thermodynamic effectivity for working velocity.
The vitality that drives muscle contraction, nerve propagation, and different physiological processes comes from the hydrolysis of a small natural compound referred to as adenosine triphosphate (ATP). Producing this gas inside a cell requires a proton gradient throughout a membrane and the motion of ATP synthase, a molecular machine. ATP synthase consists of two loosely coupled parts referred to as F1 and Fo. Single-molecule experiments have established that F1 can function individually with close to 100% effectivity. However how environment friendly are F1 and Fo in vivo? Matthew Leighton and David Sivak of Simon Fraser College in Canada have derived a solution by treating the coupled parts and their surroundings as a thermodynamic system [1]. Their new outcome could be utilized not simply to ATP synthase however to any two-component molecular machines.
Leighton and Sivak’s strategy entails deriving—from elementary thermodynamic limits—higher and decrease bounds on the efficiencies of parts. Particularly, their derivation stems from a sure on the entropy manufacturing charges of particular person parts referred to as the Jensen sure, which Leighton and Sivak obtained in 2022. Such a sure is tighter than that derived from the second regulation of thermodynamics.
The brand new bounds are helpful in figuring out the parts’ efficiencies as a result of they require data of the vitality alternate between the parts and their surroundings however not of the complicated particulars of the molecular coupling. By plugging in numbers for ATP synthase, Leighton and Sivak calculated efficiencies of fifty−85% for Fo and 70−85% for F1. Given the virtually good effectivity of remoted F1, why are the 2 parts much less environment friendly when coupled? Leighton and Sivak speculate that the connection might be a “floppy” one which prioritizes working velocity over effectivity.
–Charles Day
Charles Day is a Senior Editor for Physics Journal.
References
- M. P. Leighton and D. A. Sivak, “Inferring subsystem efficiencies in bipartite molecular machines,” Phys. Rev. Lett. 130, 178401 (2023).
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