Key result
A chemical thermodynamic model reconciles the powerstroke and chemical-Fx models for mechanochemical coupling in motor enzymes, consistent with single-molecule structural and mechanical data.
Why the study?
It was difficult to find common ground between powerstroke and chemical-Fx models of motor enzymes, despite both accounting for mechanochemical measurements.
A chemical thermodynamic model unifies the powerstroke and chemical-Fx models for mechanochemical coupling in motor enzymes.
Clarifies motor work partitioning; leaves open relevance to cardiac mechanochemistry.
Molecular motors play a central role in many biological processes, ranging from pumping blood and breathing to growth and wound healing. Through motor-catalyzed chemical reactions, these nanomachines convert the chemical free energy from ATP hydrolysis into two different forms of mechanical work. Motor enzymes perform reversible work, w rev , through an intermediate step in their catalyzed reaction cycle referred to as a working step, and they perform Fx work when they move a distance, x , against a force, F . In a powerstroke model, w rev is performed when the working step stretches a spring within a given motor enzyme. In a chemical-Fx model, w rev is performed in generating a conserved Fx potential defined external to the motor enzyme. It is difficult to find any common ground between these models even though both have been shown to account for mechanochemical measurements of motor enzymes with reasonable accuracy. Here, I show that, by changing one simple assumption in each model, the powerstroke and chemical-Fx model can be reconciled through a chemical thermodynamic model. The formal and experimental justifications for changing these assumptions are presented. The result is a unifying model for mechanochemical coupling in motor enzymes first presented by A.V. Hill in 1938 that is consistent with single-molecule structural and mechanical data.
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Josh E. Baker (2022) studied this question. Chemical thermodynamic model was evaluated. A chemical thermodynamic model reconciles the powerstroke and chemical-Fx models for mechanochemical coupling in motor enzymes, consistent with single-molecule structural and mechanical data.
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