Your Motor/Generators Are 100% Efficient

ATP synthase astounds again.  The molecular machine that generates almost all the ATP (molecular “energy pellets”) for all life was examined by Japanese scientists for its thermodynamic efficiency.  By applying and measuring load on the top part that synthesizes ATP, they were able to determine that one cannot do better at getting work out of a motor – a motor that is also a generator.

The rotating part of the two-part machine, named F₀, is embedded in the membrane, running on the proton motive force delivered by upstream machines in the electron transport chain.  These scientists concentrated on the catalytic part of the machine, named F₁, with its six lobes synthesizing three ATP per revolution (for information and animation, see CMI). Writing in PNAS,¹ Toyabe et al. had nothing to say about evolution but a lot to say about machine efficiency:

We found that the maximum work performed by F₁-ATPase per 120° step is nearly equal to the thermodynamical maximum work that can be extracted from a single ATP hydrolysis under a broad range of conditions. Our results suggested a 100% free-energy transduction efficiency and a tight mechanochemical coupling of F₁-ATPase…

The coincidence between the maximum work performed by F1-motor during the 120° rotation (Wstall) and the chemical free energy change of an ATP hydrolysis (Δμ) suggests that F₁-motor serves as a highly efficient mechanochemical free-energy transducer of F_oF₁-ATP synthase at almost 100% thermodynamic efficiency. For such a high efficiency to be achieved, a tight mechanochemical coupling is expected, that is, one ATP is hydrolyzed during every hydrolytic-direction step, whereas one ATP is synthesized during every synthetic direction step.

The article was edited by noted Harvard expert on the bacterial flagellum, Howard Berg.  The authors used machine language repeatedly, calling ATP synthase a “nanosized biological energy transducer,” a “reversible motor/generator,” a device that runs on electricity, generates torque, and performs work just like man-made machines do – only at an efficiency humans cannot come close to matching.  Most interesting was their term “reversible motor/generator.”  ATP synthase is a motor when synthesizing ATP, because the electrically-induced rotation of F_o turns a camshaft with a power takeoff performing work against a thermodynamic gradient in F₁.  It’s a generator in the other direction – when excess ATP uses its energy to turn the camshaft and make the F_o rotor turn like the turbines in a hydroelectric plant.

1. Toyabe, Watanabe-Nakayama et al. “Thermodynamic efficiency and mechanochemical coupling of F1-ATPase,” PNAS published online before print October 13, 2011, doi: 10.1073/pnas.1106787108.

Everyone should get educated a little about ATP synthase, one of the most mind-boggling, astonishing discoveries of the last 25 years.  Watch the animation at CMI and read the article.  This little device screams intelligent design.  Few are the evolutionists who will dare try to tell us how such an elegant, irreducibly-complex machine could have arisen by accident, because without it working, no incipient life would have had the means of extracting and storing energy.

That scientists can witness and even operate these tiny machines – so small 120,000 could fit on the head of a pin – is astonishing enough.  But think about this fact: nobody knew these things existed until the heyday of molecular biology, and their rotary operation was not understood until the 1990s.  Think of all the human history, the public works projects, the effort expended building machines – Archimedes’ Screw, the waterwheel, the windmill, the steam engine, the railroad, Faraday’s first attempts to build electric motors, automobiles, Mazda rotary engines – with all the geniuses in history oblivious to the fact that right within their own bodies were motor/generators of exquisite complexity and design operating at near-perfect efficiency.  This should make people excited.  This should make people humble.  This should make people thoughtful, and grateful.

Search on “ATP synthase” for many more articles in our archives about this tiny wonder of creation.