New evidence for the multiplicity of ubiquinone- and inhibitor-binding sites in the mitochondrial complex I

Citation
Jr. Tormo et E. Estornell, New evidence for the multiplicity of ubiquinone- and inhibitor-binding sites in the mitochondrial complex I, ARCH BIOCH, 381(2), 2000, pp. 241-246
Citations number
26
Categorie Soggetti
Biochemistry & Biophysics
Journal title
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
ISSN journal
00039861 → ACNP
Volume
381
Issue
2
Year of publication
2000
Pages
241 - 246
Database
ISI
SICI code
0003-9861(20000915)381:2<241:NEFTMO>2.0.ZU;2-Q
Abstract
Determination of the number of ubiquinone- and inhibitor-binding sites in t he mitochonidrial complex I (NADH:ubiquinone oxidoreductase) is a controver sial question with a direct implication for elaborating a suitable model to explain the bioenergetic mechanism of this complicated enzyme. We have use d combinations of both selective inhibitors and common ubiquinone-like subs trates to demonstrate the multiplicity of the reaction centers in the compl ex I in contrast with competition studies that have suggested the existence of a unique binding site for ubiquinone. Our results provide new evidence for the existence of at least two freely exchangeable ubiquinone-binding si tes with different specificity for substrates, as well as for a different k inetic interaction of inhibitors with the enzyme. (C) 2000 Academic Press.