Relationship to the energy-coupling system

The energy expenditure of the mitochondrial ATP-driven transhydrogenase reaction has been estimated to one ATP per NADPH formed [29,30,46,53,60-62]. Since the equilibrium constant of the nonenergy-linked transhydrogenase reaction is 0.79 [2] and that of ATP hydrolysis is about 10 M [63], the equilibrium constant of the overall reaction is also of the order of 10 M. In spite of the very unfavourable equilibrium a reversibility of the energy-Unked transhydrogenase reaction has been demonstrated using ATP production [64] or uptake of lipophilic anions [65-67] as assay. 

AB-Specific transhydrogenases are functionally coupled to the energy-transfer system of the membrane in which they are located. This coupling 

Conover, in Energy Transduction in Respiration and Photosynthesis (E. Quagliaiiello, S. Papa, and C. S. Rossi, eds.), p. 999. Adriatica Editrice, Bari, 1971. 

Since the equilibrium constant of the non-energy-linked transhydrogenase reaction is 0.79 (30) and that of ATP hydrolysis is about 10 M 

Lipmann, (iJurrents in Biochemical Research, p. 137. Wiley (Interscience), New York, 1946. 

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