Proton translocation and energy transduction in mitochondria

Abstract

Summary Data are presented showing that respiration-linked proton translocation in the inner mitochondrial membrane consists of a vectorial, single, electrogenic flow, mediated by system(s) different from cation carriers. The proton pump is, however, secondarily coupled through the ΔpH component of the proton gradient and at the level of a proton-cation antiporter, to flow of Na+ or K+. The redox proton pump appears to be directly coupled to oxido-reductions of respiratory carriers without the intervention of uncoupler-sensitive chemical intermediates. Two mechanism will be discussed for this direct coupling : (1) the oxido-reductase proton translocator of Mitchell ; (2) a so-called membrane Bohr effect, based on shifts of the pK of protonable groups of the apoprotein of electron carriers of the respiratory chain which accompany the redox changes of the electrony carrying metal centers.