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Specific effects of ATP on the kinetics of reconstituted bovine heart cytochrome‐ c oxidase
Author(s) -
Hüther Fritz-Joachim,
Kadenbach Bernhard
Publication year - 1986
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 - 10.1016/0014-5793(86)80018-7
Subject(s) - cytochrome c oxidase , cytochrome c , kinetics , chemistry , cytochrome , oxidase test , electron transport complex iv , biochemistry , cytochrome c1 , cytochrome c peroxidase , stereochemistry , enzyme , mitochondrion , coenzyme q – cytochrome c reductase , physics , quantum mechanics
Bovine heart cytochrome‐ c oxidase was reconstituted in liposomes and the kinetics of cytochrome c oxidation were measured by the polarographic and photometric method under uncoupled conditions in the presence of various polyvalent anions. In order to distinguish between specific and unspecific ionic effects of ATP, the photolabelling reagent 8‐azido‐ATP was applied. Covalently bound ATP at the enzyme complex caused the same increase of K m for cytochrome c as free ATP, if measured by the photometric assay. The increase of K m by photolabelling with 8‐azido‐ATP was completely prevented by ATP, but not by ADP. The data indicate the occurrence of a specific binding site for ATP at the cytosolic side of cytochrome‐ c oxidase, which, after binding of ATP, changes the kinetics of cytochrome c oxidation.