Open AccessThe Proton Pump of Cytochrome c Oxidase and Its Stoichiometry
Author(s) -
SIGEL Erwin,
CARAFOLI Ernesto
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb20903.x
Subject(s) - cytochrome c oxidase , proton , antimycin a , cytochrome , proton pump , cytochrome c , oxygen , electron transport complex iv , valinomycin , chemistry , electron , cytochrome c1 , mitochondrion , oxidase test , stoichiometry , coenzyme q – cytochrome c reductase , membrane , biochemistry , physics , enzyme , organic chemistry , atpase , quantum mechanics
The operation of cytochrome c oxidase with ascorbate/ N,N,N′,N′ ‐tetramethyl‐ p ‐phenylene‐diamine as substrate in antimycin‐A‐inhibited rat liver mitochondria is coupled to proton ejection. Measurements of the initial rate of valinomycin‐dependent K + uptake have shown that nearly 4 K + are taken up as 2 electrons are transferred from cytochrome c to oxygen. This proves directly that a charge separation of nearly 4 occurs across the inner mitochondrial membrane each time 2 electrons are transferred to oxygen. Measurements of the initial rate of proton movement after addition of the reductant show that about 1.6 protons are released by the mitochondria as 2 electrons are transferred from cytochrome c to oxygen. The data support the suggestion of a proton pump coupled to the operation of cytochrome c oxidase [Wikström, M. F. K. (1977) Nature (Lond.) 266 , 271–273].