title: Fungal quinone pigments as oxidizers and inhibitors of mitochondrial NADH:ubiquinone reductase.
abstract: The interaction of fungal quinone pigments bostricoidin, fusarubin, javanicin, and 2-oxyjuglone with mitochondrial NADH:ubiquinone reductase (complex I, EC 1.6.99.3) has been studied. The bimolecular rate constants (turnover number (TN)/Km) of rotenone-insensitive reduction of these compounds are in the range of 1.2 x 10(4)-1.6 x 10(5) M-1s-1. 2-Oxyjuglone acts as inhibitor of NADH:ferricyanide reductase reaction of complex I (KI = 30 microM). All quinone pigments, except javanicin, decrease the TN of reduction of 5,8-dioxy-1,4-naphtoquinone being reduced at its binding site but with significantly lower TN. They do not affect the rotenone-sensitive reduction of ubiquinone-1. The binding of quinone pigments close to the NADH and ferricyanide binding site is suggested. It seems that quinone pigments, especially 2-oxyjuglone, react with complex I faster than it follows from their approximate values of one-electron reduction potential calculated from their reactivities with flavocychrome b2 and adrenodoxin.
authors.affiliation: Institute of Biochemistry, Lithuanian Academy of Sciences, Mokslininku.
authors.forename: D A
authors.initials: DA
authors.lastname: Bironaité
authors.forename: N K
authors.initials: NK
authors.lastname: Cénas
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Anusevicius
authors.forename: A G
authors.initials: AG
authors.lastname: Medentsev
authors.forename: V K
authors.initials: VK
authors.lastname: Akimenko
authors.forename: S A
authors.initials: SA
authors.lastname: Usanov
mesh_terms: D000818:Animals; D002417:Cattle; D042967:Electron Transport Complex I; D005658:Fungi; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology*; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010084:Oxidation-Reduction; D010860:Pigments, Biological / Q000494:pharmacology*; D011809:Quinones / Q000494:pharmacology*; D012402:Rotenone / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D010860:Pigments, Biological; D011809:Quinones; D012402:Rotenone; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I