Thermodynamics and control of proton motive free-energy transduction.

Theories for (mosaic) non-equilibrium thermodynamics and the control of biological free-energy transduction are briefly recounted. Subsequently they are used to answer questions concerning properties of bacteriorhodopsin and the proton pumps in the mitochondrial respiratory chain, as well as concerning the presence of flux control in the non-irreversible reactions in free-energy transducers. Inhibition of bacteriorhodopsin by the membrane potential, respiratory control by delta muH and the theoretical P/O ratio are central in these discussions. Finally, specific thermodynamic and control properties of systems with localized ('mosaic', 'direct') energy coupling are discussed.