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Effect of ethoxyformic anhydride on the Rieske iron—sulfur protein of bovine heart ubiquinol: Cytochrome c oxidoreductase
Author(s) -
Ohnishi T.,
Meinhardt S.W.,
von Jagow G.,
Yagi T.,
Hatefi Y.
Publication year - 1994
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(94)01021-8
Subject(s) - ubiquinol , chemistry , iron–sulfur cluster , oxidoreductase , ferredoxin , hydroxylamine , cytochrome c , sulfur , electron transfer , cytochrome , coenzyme q – cytochrome c reductase , stereochemistry , biochemistry , photochemistry , mitochondrion , organic chemistry , enzyme
Treatment of bovine heart ubiquinol‐cytochrome c oxidoreductase (complex III, bc 1 complex) with ethoxyformic anhydride (EFA) inhibits electron transfer between cytochromes b and c 1 [Yagi et al., Biochemistry 21 (1982) 4777–4782]. This paper shows that EFA alters the EPR lineshape of the Rieske iron—sulfur cluster in complex III and in the isolated Rieske protein without a significant decrease of spin concentration. The effect of EFA on the Rieske iron—sulfur cluster is competitive with that of Q o site inhibitors, such as stigmatellin, and is completely reversed by hydroxylamine. These results are consistent with the possible ethoxyformylation by EFA of histidine ligands of the Rieske iron—sulfur cluster at the non‐iron binding imidazole nitrogens.