Mammalian complex i pumps 4 protons per 2 electrons at high and physiological proton motive force in living cells

Abstract

Background: The H+/2e- stoichiometry of complex I has been questioned based on recent crystal structures. Results: A new method of quantitating proton motive force and ubiquinone redox potential was used to determine the thermodynamic poise of complex I in living cells. Conclusion: The poise is consistent with pumping 4 not 3H+/2e-. Significance: This new methodology can quantitate electron transport chain function in living cells. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.