Steady-state proton translocation in bovine heart mitochondrial bc1 complex reconstituted into liposomes.
The effect of different anions on the steady-state proton translocation in bovine bc1 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 bc1 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.
Cocco
T
T
Institute of Medical Biochemistry and Chemistry, University of Bari, Italy.
Di Paola
M
M
Minuto
M
M
Carlino
V
V
Papa
S
S
Lorusso
M
M
D000818:Animals; D001386:Azides / Q000494:pharmacology; D001692:Biological Transport; D002417:Cattle; D003580:Cytochromes / Q000378:metabolism; D014450:Electron Transport Complex III / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D008929:Mitochondria, Heart / Q000187:drug effects / Q000201:enzymology*; D011522:Protons
D001386:Azides; D003580:Cytochromes; D008081:Liposomes; D011522:Protons; D014450:Electron Transport Complex III