Redox components and structure of the respiratory NADH:ubiquinone oxidoreductase (complex I)
| Autor: | Hanns Weiss, Ulrich Schulte, Dierk Scheide, Kevin Leonard, Tim Rasmussen, Thorsten Friedrich, Angela Schlitt, Anke Abelmann, Vincent Guénebaut, Lars Kintscher, Benedikt Brors |
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| Rok vydání: | 1998 |
| Předmět: |
Models
Molecular Biophysics Flavin mononucleotide Purple bacteria Redox Biochemistry Cofactor Rhodobacter capsulatus Neurospora crassa chemistry.chemical_compound Electron transfer NADH:ubiquinone oxidoreductase Oxidoreductase Complex I NAD(P)H Dehydrogenase (Quinone) Electron microscopy Escherichia coli Computer Simulation chemistry.chemical_classification FeS-cluster biology Thermus thermophilus NADH dehydrogenase Electron Spin Resonance Spectroscopy Cell Biology biology.organism_classification chemistry biology.protein Spectrophotometry Ultraviolet Oxidation-Reduction EPR spectroscopy |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1365(1-2):215-219 |
| ISSN: | 0005-2728 |
| DOI: | 10.1016/s0005-2728(98)00070-x |
| Popis: | The proton-pumping NADH:ubiquinone oxidoreductase is the first complex in the respiratory chains of many purple bacteria and of mitochondria of most eucaryotes. The bacterial complex consists of 14 different subunits. The mitochondrial complex contains at least 29 additional proteins that do not directly participate in electron transfer and proton translocation. We analysed electron micrographs of isolated and negatively stained complex I particles from Escherichia coli and Neurospora crassa and obtained three-dimensional models of both complexes at medium resolution. Both have the same L-shaped overall structure with a peripheral arm protruding into the aqueous phase and a membrane arm extending into the membrane. The two arms of the bacterial complex are only slightly shorter than those of the mitochondrial complex although the protein mass of the former is only half of that of the latter. The presence of a novel redox group in the membrane arm of the complex is discussed. This group has been detected in the N. crassa complex by means of UV-visible spectroscopy. After reduction with an excess of NADH and reoxidation by the lactate dehydrogenase reaction, a reduced-minus-oxidized difference spectrum was obtained that cannot be attributed to the known cofactors flavin mononucleotide (FMN) and the FeS clusters N1, N2, N3 and N4. Due to its positive midpoint potential the novel group is believed to transfer electrons from the FeS clusters to ubiquinone. Its role in proton translocation is discussed. |
| Databáze: | OpenAIRE |
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