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Preparation of Membrane Crystals of Mitochondrial NADH:Ubiquinone Reductase and Ubiquinol:Cytochrome C Reductase and Structure Analysis by Electron Microscopy
Published in Hartmut Michel, Crystallization of Membrane Proteins, 1991
The mitochondrial system of oxidative phosphorylation is contained in the inner membrane in the form of four discrete enzyme complexes. They are the NADH:ubiquinone oxidoreductase (NADH:Q reductase), the ubiquinol:ferricytochrome c oxidoreductase (cytochrome reductase), the ferrocytochrome c:oxygen oxidoreductase (cytochrome oxidase), and the ATP-synthase. The three electron transfer enzymes are concerned with the generation of transmembraneous protonic potential. They link downhill electron flow with uphill proton translocation across the membrane directed outwards from the mitochondria. The ATP-synthase is the main consumer of the protonic potential and couples downhill and inward flow of protons with synthesis of ATP (for a review see Reference 1).
Copper
Published in Judy A. Driskell, Ira Wolinsky, Sports Nutrition, 2005
Philip G. Reeves, W. Thomas Johnson
Four oligomeric enzymes, NADH:ubiquinone oxidoreductase (complex I), succinate:ubiquinone oxidoreductase (complex II), ubiquinol:cytochrome c oxidoreductase (complex III) and ferrocyto-chrome c:oxygen oxidoreductase (complex IV), compose the mitochondrial electron transport chain located in the inner mitochondrial membrane. Electrochemical energy derived from the transfer of electrons between these enzymes to molecular oxygen drives the vectorial translocation of protons across the inner mitochondrial membrane that provides the energy required for ATP synthesis. Although electron transport accounts for about 85–90% of the oxygen utilized by cells, not all of the oxygen consumed by the electron transport chain is converted to water; about 1–5% is converted to superoxide.97–99 Thus, a 70-kg adult who uses about 14.7 moles of O2/day would produce about 0.15–0.74 moles of mitochondria-generated superoxide on a daily basis. Much of the superoxide (O2•-) formed is converted to hydrogen peroxide (H2O2) by a manganese-dependent form of super-oxide dismutase (MnSOD) located in the mitochondrial matrix. However, a portion of superoxide generated by the electron transport chain escapes conversion by MnSOD and is available to react with H2O2 to form hydroxyl radicals (HO_) by the Haber-Weiss reaction catalyzed by mitochondrial iron (equation 1). H2O2 can also react with mitochondrial iron to produce hydroxyl radicals by the Fenton reaction (equation 2).
Genome-wide association studies of stress score in a Korean Cohort
Published in Stress, 2021
In this study, genes that increase susceptibility to stress were identified using results from a stress survey. In terms of the risk of stress, a score was calculated from the sum of all survey results. Following this, the group of subjects who scored within a range in which a higher proportion of insomnia was present were defined as High Stress and analyzed. Although no significant genetic indicator at the genome-wide significant level was found in this study, indicators at the genome-wide suggestive level were identified, reflecting high potential. The most significant SNP of GenST (rs9353437) was found in an epidermal growth factor gene (eyes shut homolog, EYS) and expressed in the photoreceptor layer of the retina. The GWAS results of PhyST showed a significant SNP (rs4924370) in a spliceosomal factor (Aquarius intron-binding spliceosomal factor, AQR). Notably, the second most significant SNP (rs1991002) was found in an oxidoreductase gene (NADH:Ubiquinone Oxidoreductase Subunit S4, NDUFS4) and was marginally associated (p-value < 0.05) with GenST, MenST, and ActST.
Metformin as a potential therapeutic for neurological disease: mobilizing AMPK to repair the nervous system
Published in Expert Review of Neurotherapeutics, 2021
Sarah Demaré, Asha Kothari, Nigel A. Calcutt, Paul Fernyhough
Other effects of metformin on mitochondrial respiratory function have also been observed. Mitochondrial respiratory chain complex 1 (NADH:ubiquinone oxidoreductase) was inhibited in primary rat hepatocytes by metformin treatment [36]. Metformin also prevented glutamate and malate oxidation in a dose and time dependent manner, further suggesting inhibition of complex 1. This effect required intact cells and did not occur in isolated mitochondria, suggesting that metformin did not directly inhibit complex 1 but operated indirectly [37]. More recent research has shown that isolated mitochondrial complexes can be weakly and reversibly inhibited by metformin, most likely by acting on conserved core regions of the enzyme [38]. Complex 3 of the respiratory chain and ATP synthase were also inhibited by metformin. The redox state of mitochondria, as determined by NADH:NAD+ ratios in hepatocytes, responded to metformin treatment in a manner similar to that of rotenone, a known inhibitor of complex 1 [39].