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Inhibition of membrane‐bound cytochrome c oxidase by zinc ions: High‐affinity Zn 2+ ‐binding site at the P‐side of the membrane
Author(s) -
Vygodina Tatiana V.,
Zakirzianova Wiolanta,
Konstantinov Alexander A.
Publication year - 2008
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/j.febslet.2008.11.018
Subject(s) - cytochrome c oxidase , chemistry , oxidase test , electron transport complex iv , zinc , phospholipid , membrane , enzyme , submitochondrial particle , vesicle , biochemistry , organic chemistry
In the presence of the uncoupler, external zinc ions inhibit rapidly turnover of cytochrome c oxidase reconstituted in phospholipid vesicles or bound to the membrane of intact mitochondria. The effect is promoted by electron leaks into the oxidase during preincubation with Zn 2+ . Inhibition of liposome‐bound bovine cytochrome oxidase by external Zn 2+ titrates with a K i of 1 ± 0.3 μM. Presumably, the Zn 2+ ‐binding group at the positively charged side is not reactive in the oxidized enzyme, but becomes accessible to the cation in some partially reduced state(s) of the oxidase; reduction of Cu B is tentatively proposed to be responsible for the effect.