ABSTRACT
The pathway for the complete oxidation of pyruvate begins with an inner membrane transporter, a symport with protons, for entry into the mitochondrial matrix. For the Mitchell hypothesis, the uncoupler provides a shortcut to proton re-entry into the mitochondria: the protonophore itself. Krebs and colleagues recognized that the amount of adenosine triphosphate the mitochondria must produce must be determined by metabolic need, yet this experiment would suggest instead that a kinetic limitation of the exchanger is rate limiting for mitochondrial energy production. Ubiquinone (QH2) is a pool collecting electrons from both sides of the mitochondrial inner membrane, passing them subsequently to the electron transport chain. Thus, the Krebs cycle, in common with fatty acid oxidation, and some amino acid oxidation pathways are generators of the energy-rich mobile cofactors NADH and QH2. There are two connections between glycolytic and mitochondrial oxidation of glucose: pyruvate and NADH.
