title: An ATP/2e-stoichiometry of 1 1/2 is thermodynamically possible for site 3 of oxidative phosphorylation.
abstract: Free energy changes for ATP synthesis (delta GP) and 2e(-)-transfer across Site 3 (delta GR) were determined during oxidative phosphorylation by rat liver mitochondria. At static head, -delta GR/delta GP ranged narrowly between 1.55 and 1.59 with five different respiratory substrates. Thus, an ATP/2e- of 1 1/2 at Site 3 is thermodynamically possible with regards to overall reactants and products. Using nonequilibrium thermodynamics, phenomenological stoichiometries were close to 1 1/2 for all substrates suggesting that ATP/2e- at Site 3 is, in fact, 1 1/2. An ATP/2e- of 1 1/2 can only be possible if H+/O is 4 for cytochrome oxidase.
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000818:Animals; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000502:physiology*; D004583:Electrons; D008930:Mitochondria, Liver / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D051381:Rats; D013816:Thermodynamics
chemical_list: D000255:Adenosine Triphosphate; D003576:Electron Transport Complex IV