Steady-State Proton Translocation in Bovine Heart Mitochondrial bc 1 Complex Reconstituted into Liposomes

Abstract The effect of different anions on the steady-state proton translocation in bovine bc 1 complex reconstituted in liposomes was studied. The H+/e − ratio for vectorial proton translocation is at the steady state definitely lower than that measured at level flow, (0.3 vs. 1.0). The presence of...
Ausführliche Beschreibung

Abstract The effect of different anions on the steady-state proton translocation in bovine bc 1 complex reconstituted in liposomes was studied. The H+/e − ratio for vectorial proton translocation is at the steady state definitely lower than that measured at level flow, (0.3 vs. 1.0). The presence of azide or arachidonate at micro- and submicromolar concentrations, respectively, gave a substantial reactivation of the proton pumping activity at the steady state, without any appreciable effect on respiration-dependent transmembrane pH difference. Addition of azide to turning-over bc 1 vesicles also caused a transition of b cytochromes toward oxidation. The results are discussed in terms of possible involvement of an acidic residue in the protonation of the semiquinone/quinol couple at the N side of the membrane. Ausführliche Beschreibung