LAUSR

Abstract ATP synthesis in mitochondria is driven by the pH gradient between lipid membranes, and a proton-motive force (PMF) forms along the respiratory electron-transport chain. The reasons for these phenomena remain unclear. In an unbuffered quinone solution, acids induce the formation of new cathodic peaks, whose peak potential is dependent on their pKa. Thus, the protons of acids have a potential defined as “protonic potential.” Herein, the energy of proton translocation was easily quantified by protonic potential. We observed that the redox potential of chemical reactions can be transformed into the protonic potential of Bronsted−Lowry acids and bases in an unbuffered solution. We postulated that in the mitochondrial membrane, the redox potential of the respiratory chain can be transformed to protonic potential and that the PMF originates from the protonic potential difference between compounds. Ultimately, the protonic potential energy derived from redox reactions was stored in the ATP.