Premium
Zn 2+ binding to the cytoplasmic side of Paracoccus denitrificans cytochrome c oxidase selectively uncouples electron transfer and proton translocation 1
Author(s) -
Kannt Aimo,
Ostermann Thomas,
Müller Hannelore,
Ruitenberg Maarten
Publication year - 2001
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(01)02719-3
Subject(s) - paracoccus denitrificans , cytochrome c oxidase , chemistry , electron transport complex iv , proton , oxidase test , cytochrome , electron transfer , cytochrome c , analytical chemistry (journal) , photochemistry , biochemistry , enzyme , chromatography , mitochondrion , physics , quantum mechanics
Using a combination of stopped‐flow spectrophotometric proton pumping measurements and time‐resolved potential measurements on black lipid membranes, we have investigated the effect of Zn 2+ ions on the proton transfer properties of Paracoccus denitrificans cytochrome c oxidase. When zinc was enclosed in the interior of cytochrome c oxidase containing liposomes, the H / e stoichiometry was found to gradually decrease with increasing Zn 2+ concentration. Half‐inhibition of proton pumping was observed at [Zn 2+ ] i =75 μM corresponding to about 5–6 Zn 2+ ions per oxidase molecule. In addition, there was a significant increase in the respiratory control ratio of the proteoliposomes upon incorporation of Zn 2+ . Time‐resolved potential measurements on a black lipid membrane showed that the electrogenic phases slowed down in the presence of Zn 2+ correspond to phases that have been attributed to proton uptake from the cytoplasmic side and to proton pumping. We conclude that Zn 2+ ions bind close to or within the two proton transfer pathways of the bacterial cytochrome c oxidase.