Characterization of Two Quinone Radicals in the NADH:Ubiquinone Oxidoreductase from Escherichia coli by a Combined Fluorescence Spectroscopic and Electrochemical Approach
| Autor: | Thorsten Friedrich, Petra Hellwig, Mariana Voicescu, Emmanuel Gnandt, Ruth Hielscher, Michelle Yegres |
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| Přispěvatelé: | Chimie de la matière complexe (CMC), Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de Strasbourg, Centre National de la Recherche Scientifique (CNRS)-Université Louis Pasteur - Strasbourg I-Institut de Chimie du CNRS (INC) |
| Rok vydání: | 2013 |
| Předmět: |
Models
Molecular Free Radicals Flavin mononucleotide Photochemistry Biochemistry Redox Electron Transport 03 medical and health sciences Electron transfer chemistry.chemical_compound Oxidoreductase Redox titration Benzoquinones Escherichia coli 030304 developmental biology chemistry.chemical_classification 0303 health sciences Electron Transport Complex I biology 030302 biochemistry & molecular biology NADH dehydrogenase Electrochemical Techniques [CHIM.CATA]Chemical Sciences/Catalysis Electron transport chain Quinone Spectrometry Fluorescence chemistry biology.protein |
| Zdroj: | Biochemistry Biochemistry, 2013, 52 (50), pp.8993-9000. ⟨10.1021/bi4009903⟩ |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi4009903 |
| Popis: | PMID: 24279322; The NADH:ubiquinone oxidoreductase (complex I) couples the transfer of electrons from NADH to ubiquinone with the translocation of protons across the membrane. It was proposed that the electron transfer involves quinoid groups localized at the end of the electron transfer chain. To identify these groups, fluorescence excitation and emission spectra of Escherichia coli complex I and its fragments, namely, the NADH dehydrogenase fragment containing the flavin mononucleotide and six iron-sulfur (Fe-S) clusters, and the quinone reductase fragment containing three Fe-S clusters were measured. Signals sensitive to reduction by either NADH or dithionite were detected within the complex and the quinone reductase fragment and attributed to the redox transition of protonated ubiquinone radicals. A fluorescence spectroscopic electrochemical redox titration revealed midpoint potentials of -37 and- 235 mV (vs the standard hydrogen electrode) for the redox transitions of the quinone radicals in complex I at pH 6 with an absorption around 325 nm and a fluorescence emission at 460/475 nm. The role of these cofactor(s) for electron transfer is discussed. |
| Databáze: | OpenAIRE |
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