Ubiquinone
Mostrando 13-24 de 237 artigos, teses e dissertações.
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13. Sequence of b cytochromes relative to ubiquinone in the electron transport chain of Escherichia coli.
A ubiquinone-deficient mutant, carrying mutations in two genes affecting ubiquinone biosynthesis, has been used, in comparison with a normal strain, to determine the sequence of some of the components of the electron transport chain of Escherichia coli. The amounts of cytochromes reduced during aerobic steady-state conditions were estimated by comparing low-
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14. Function of Ubiquinone in Escherichia coli: a Mutant Strain Forming a Low Level of Ubiquinone
A ubiquinone-deficient mutant of Escherichia coli K-12 forming 20% of the normal amount of ubiquinone was compared with a normal strain. This lowered concentration of ubiquinone is still four times the concentration of cytochrome b1. The mutant strain grew more slowly than the normal strain on a minimal medium with glucose as sole source of carbon and gave a
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15. Effects of Atovaquone and Diospyrin-Based Drugs on Ubiquinone Biosynthesis in Pneumocystis carinii Organisms
The naphthoquinone atovaquone is effective against Plasmodium and Pneumocystis carinii carinii. In Plasmodium, the primary mechanism of drug action is an irreversible binding to the mitochondrial cytochrome bc1 complex as an analog of ubiquinone. Blockage of the electron transport chain ultimately inhibits de novo pyrimidine biosynthesis since dihydroorotate
American Society for Microbiology.
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16. Phenotypes of Fission Yeast Defective in Ubiquinone Production Due to Disruption of the Gene for p-Hydroxybenzoate Polyprenyl Diphosphate Transferase
Ubiquinone is an essential component of the electron transfer system in both prokaryotes and eukaryotes and is synthesized from chorismate and polyprenyl diphosphate by eight steps. p-Hydroxybenzoate (PHB) polyprenyl diphosphate transferase catalyzes the condensation of PHB and polyprenyl diphosphate in ubiquinone biosynthesis. We isolated the gene (designat
American Society for Microbiology.
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17. Pathway for Ubiquinone Biosynthesis in Escherichia coli K-12: Gene-Enzyme Relationships and Intermediates
Seven ubiquinone-deficient mutants of Escherichia coli, each of which accumulates two phenolic precursors of ubiquinone, have been characterized, and the accumulated compounds have been identified. The mutants accumulate small quantities of 2-octaprenyl-6-methoxyphenol, which was isolated and characterized by nuclear magnetic resonance and mass spectrometry,
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18. Low Ubiquinone Content in Escherichia coli Causes Thiol Hypersensitivity
Thiol hypersensitivity in a mutant of Escherichia coli (IS16) was reversed by complementation with a plasmid that carried the ubiX gene. The mutant had low ubiquinone content. Complementation elevated the ubiquinone level and eliminated thiol hypersensitivity. Analysis of chromosomal ubiX genes indicated that both parent and mutant strains were ubiX mutants.
American Society for Microbiology.
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19. Alternative Oxidase Activity and the Ubiquinone Redox Level in Soybean Cotyledon and Arum Spadix Mitochondria during NADH and Succinate Oxidation.
In Arum and soybean (Glycine max L.) mitochondria, the dependence of the alternative oxidase activity on the redox level of ubiquinone, with NADH and succinate as substrates, was studied, using a voltametric procedure to measure the ubiquinone redox poise in the mitochondrial membrane. The results showed that when the enzyme was activated by pyruvate the rel
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20. Function of Ubiquinone in Electron Transport from Reduced Nicotinamide Adenine Dinucleotide to Nitrate and Oxygen in Aerobacter aerogenes
The possible role of quinones in the electron transport system of Aerobacter aerogenes was investigated. The only quinone found in measurable amounts in bacteria grown in minimal media under both aerobic and anaerobic conditions was ubiquinone-8. Membrane-bound ubiquinone-8 could be removed by extraction with pentane, or destroyed by ultraviolet irradiation,
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21. Mutant Strains of Escherichia coli K-12 Unable to Form Ubiquinone
A strain of Escherichia coli was isolated which was unable to form ubiquinone. This mutant was obtained by selecting strains unable to grow on malate as sole source of carbon. Such strains were further screened by examination of the quinone content of cells grown on a glucose medium. A mutant unable to form vitamin K was also isolated by this procedure. A ge
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22. Atpenins, potent and specific inhibitors of mitochondrial complex II (succinate-ubiquinone oxidoreductase)
Enzymes in the mitochondrial respiratory chain are involved in various physiological events in addition to their essential role in the production of ATP by oxidative phosphorylation. The use of specific and potent inhibitors of complex I (NADH-ubiquinone reductase) and complex III (ubiquinol-cytochrome c reductase), such as rotenone and antimycin, respective
The National Academy of Sciences.
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23. Characterization and Genetic Analysis of Mutant Strains of Escherichia coli K-12 Accumulating the Ubiquinone Precursors 2-Octaprenyl-6-Methoxy-1,4-Benzoquinone and 2-Octaprenyl-3-Methyl-6-Methoxy-1,4-Benzoquinone
The ubiquinone precursors, 2-octaprenyl-6-methoxy-1,4-benzoquinone and 2-octaprenyl-3-methyl-6-methoxy-1,4-benzoquinone, were isolated from ubiquinone-deficient mutants of Escherichia coli and identified by nuclear magnetic resonance and mass spectrometry. Mutants accumulating 2-octaprenyl-6-methoxy-1,4-benzoquinone and 2-octaprenyl-3-methyl-6-methoxy-1,4-be
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24. Mutants of Escherichia coli K-12 Blocked in the Final Reaction of Ubiquinone Biosynthesis: Characterization and Genetic Analysis
The ubiquinone precursor 2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1, 4-benzoquinone was isolated from two ubiquinone-deficient mutants of Escherichia coli and identified by nuclear magnetic resonance and mass spectrometry. The results of genetic analysis of the mutants indicate that each mutant carries a mutation in a gene designated ubiG which was located,