EPR studies of the possible binding sites of the cluster N2, semiquinones, and specific inhibitors of the NADH:quinone oxidoreductase (complex I)

Ohnishi, Tomo̧ko; Magnitsky, Sergey; Toulokhonova, Larisa; Yano, Takahiro; Yagi, Takao; Burbaev, D. Sh.; Vinogradov, Andrei D.

doi:10.1042/bst0270586

Cited by 20 publications

(7 citation statements)

References 6 publications

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“…Taken together, these observations further suggest a second binding point to the enzyme. Indeed, there is evidence for at least two inhibitor-binding sites in complex I ,,,, and also two very close ubiquinone-binding sites, , likely to be located in the same domain of the enzyme. , Therefore, we propose a double binding of ACG with the enzyme. The main point is clearly a ubiquinone-binding site antagonized by the central part of the molecule in which the α,α‘-dihydoxylated THF system competes with the quinone head of the substrate.…”

Section: Resultsmentioning

confidence: 70%

Semisynthesis of Antitumoral Acetogenins: SAR of Functionalized Alkyl-Chain Bis-Tetrahydrofuranic Acetogenins, Specific Inhibitors of Mitochondrial Complex I

et al. 2000

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The acetogenins of Annonaceae are known by their potent cytotoxic activity. In fact, they are promising candidates as a new future generation of antitumoral drugs to fight against the current chemiotherapic resistant tumors. The main target enzyme of these compounds is complex I (NADH:ubiquinone oxidoreductase) of the mitochondrial respiratory chain, a key enzymatic complex of energy metabolism. In an attempt to characterize the relevant structural factor of the acetogenins that determines the inhibitory potency against this enzyme, we have prepared a series of bis-tetrahydrofuranic acetogenins with different functional groups along the alkyl chain. They comprise several oxo, hydroxylimino, mesylated, triazido, and acetylated derivatives from the head series compounds rolliniastatin-1, guanacone, and squamocin. Our results suggest a double binding point of acetogenins to the enzyme involving the alpha,alpha'-dihydroxylated tetrahydrofuranic system as well as the alkyl chain that links the terminal alpha, beta-unsaturated-gamma-methyl-gamma-lactone. The former mimics and competes with the ubiquinone substrate. The latter modulates the inhibitory potency following a complex outline in which multiple structural factors probably contribute to an appropriate conformation of the compound to penetrate inside complex I.

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Section: Resultsmentioning

confidence: 70%

Semisynthesis of Antitumoral Acetogenins: SAR of Functionalized Alkyl-Chain Bis-Tetrahydrofuranic Acetogenins, Specific Inhibitors of Mitochondrial Complex I

et al. 2000

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“…During steady state NADH oxidation ubisemiquinone radicals could be identified in submitochondrial particles (SMP) from bovine heart by various groups using EPR spectroscopic approaches [20,43–46]. T. Ohnishi and coworkers identified three types of SQ species (SQ Nf , SQ slow , SQ Nx ) that contribute to the low temperature EPR signals (40 K, g =2.004) in tightly coupled SMP.…”

Section: Semiquinonesmentioning

confidence: 99%

Proton pumping by NADH:ubiquinone oxidoreductase. A redox driven conformational change mechanism?

et al. 2003

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The modular evolutionary origin of NADH:ubiquinone oxidoreductase (complex I) provides useful insights into its functional organization. Iron^sulfur cluster N2 and the PSST and 49 kDa subunits were identi¢ed as key players in ubiquinone reduction and proton pumping. Structural studies indicate that this 'catalytic core' region of complex I is clearly separated from the membrane. Complex I from Escherichia coli and Klebsiella pneumoniae was shown to pump sodium ions rather than protons. These new insights into structure and function of complex I strongly suggest that proton or sodium pumping in complex I is achieved by conformational energy transfer rather than by a directly linked redox pump. ß

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“…Mitochondrial NADH:ubiquinone oxidoreductase (complex I) or its prokaryotic homologues (NDH-1) catalyse the oxidation of intramitochondrial or cytoplasmic NADH by ubiquinone coupled with vectorial translocation of protons across the inner mitochondrial (cytoplasmic) membrane. Mammalian complex I is the largest component of the mitochondrial respiratory chain and is composed of 46 different subunits [1] harbouring at least eight distinct redox components [2]. Bacterial operons encoding NDH-1 contain only 13-14 genes [3][4][5] and their transcription products are highly homologous with 14 core subunits of the mammalian complex I [6].…”

Section: Introductionmentioning

confidence: 99%

Inhibitory effect of palmitate on the mitochondrial NADH:ubiquinone oxidoreductase (complex I) as related to the active–de-active enzyme transition

Loskovich

Grivennikova

Cecchini

et al. 2005

Biochemical Journal

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Palmitate rapidly and reversibly inhibits the uncoupled NADH oxidase activity catalysed by activated complex I in inside-out bovine heart submitochondrial particles (IC50 extrapolated to zero enzyme concentration is equal to 9 microM at 25 degrees C, pH 8.0). The NADH:hexa-ammineruthenium reductase activity of complex I is insensitive to palmitate. Partial (approximately 50%) inhibition of the NADH:external quinone reductase activity is seen at saturating palmitate concentration and the residual activity is fully sensitive to piericidin. The uncoupled succinate oxidase activity is considerably less sensitive to palmitate. Only a slight stimulation of tightly coupled respiration with NADH as the substrate is seen at optimal palmitate concentrations, whereas complete relief of the respiratory control is observed with succinate as the substrate. Palmitate prevents the turnover-induced activation of the de-activated complex I (IC50 extrapolated to zero enzyme concentration is equal to 3 microM at 25 degrees C, pH 8.0). The mode of action of palmitate on the NADH oxidase is qualitatively temperature-dependent. Rapid and reversible inhibition of the complex I catalytic activity and its de-active to active state transition are seen at 25 degrees C, whereas the time-dependent irreversible inactivation of the NADH oxidase proceeds at 37 degrees C. Palmitate drastically increases the rate of spontaneous de-activation of complex I in the absence of NADH. Taken together, these results suggest that free fatty acids act as specific complex I-directed inhibitors; at a physiologically relevant temperature (37 degrees C), their inhibitory effects on mitochondrial NADH oxidation is due to perturbation of the pseudo-reversible active-de-active complex I transition.

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EPR studies of the possible binding sites of the cluster N2, semiquinones, and specific inhibitors of the NADH:quinone oxidoreductase (complex I)

Cited by 20 publications

References 6 publications

Semisynthesis of Antitumoral Acetogenins: SAR of Functionalized Alkyl-Chain Bis-Tetrahydrofuranic Acetogenins, Specific Inhibitors of Mitochondrial Complex I

Semisynthesis of Antitumoral Acetogenins: SAR of Functionalized Alkyl-Chain Bis-Tetrahydrofuranic Acetogenins, Specific Inhibitors of Mitochondrial Complex I

Proton pumping by NADH:ubiquinone oxidoreductase. A redox driven conformational change mechanism?

Inhibitory effect of palmitate on the mitochondrial NADH:ubiquinone oxidoreductase (complex I) as related to the active–de-active enzyme transition

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