Mechanism of proton translocation associated to oxidation of N,N,N′,N′-tetramethyl- p-phenylenediamine in rat liver mitochondria

Abstract

A kinetic analysis is presented of proton translocation, TMPD + formation and oxidation of endogenous respiratory carriers during oxygen pulses of TMPD supplemented rat-liver mitochondria. The results show that antimycin-insensitive proton ejection observed under coupled conditions derives from oxidation of endogenous respiratory carriers and re-reduction of TMPD + by hydrogenated donors and not from proton pumping by cytochrome oxidase as claimed by other investigators. The observations presented provide an example of certain interpretative difficulties in the use of redox mediators and of the methodological approaches that can be used to avoid these.