The Residual Protonmotive Force in Mitochondria after an Oxygen Pulse

Abstract

Both from irreversible thermodynamics and from mass-action kinetics it can be derived that upon anaerobiosis in an O2-pulse experiment the protonmotive force across a mitochondrial membrane undergoes a sudden drop. Under representative conditions the protonmotive force after the drop (the residual protonmotive force) is < 3 kJ.cntdot.mol-1 as opposed to steady-state values for the protonmotive force of 19 kJ.cntdot.mol-1. Corrections for proton leakage in pulse experiments by back extrapolation underestimate proton leakage. Consequently the observed H+/O stoichiometries must underestimate the true H+/O ratios.