Electron transport in Paracoccus halodenitrificans and the role of ubiquinone.
The membrane-bound NADH oxidase of Paracoccus halodenitrificans was inhibited by dicoumarol, 2-n-heptyl-4-hydroxy-quinoline-N-oxide (HQNO), and exposure to ultraviolet light (at 366 nm).  When the membranes were extracted with n-pentane, NADH oxidase activity was lost.  Partial restoration was achieved by adding the ubiquinone fraction extracted from the membranes.  Succinate oxidation was not inhibited by dicoumarol or HQNO, but was affected by ultraviolet irradiation or n-pentane extraction.  However, the addition of the ubiquinone fraction to the membranes extracted with n-pentane did not restore enzyme activity.  These observations suggested that NADH and succinate were not oxidized through a common ubiquinone pool.
Hochstein
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Extraterrestrial Research Division, National Aeronautics and Space Administration, Ames Research Centre, Moffett Field, CA 94035, USA.
Cronin
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D001728:Dicumarol / Q000494:pharmacology; D004579:Electron Transport / Q000187:drug effects / Q000528:radiation effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006912:Hydroxyquinolines / Q000494:pharmacology; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000528:radiation effects*; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000528:radiation effects*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000528:radiation effects*; D010101:Oxygen Consumption / Q000187:drug effects; D010230:Paracoccus / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D010420:Pentanes / Q000494:pharmacology; D011809:Quinones / Q000378:metabolism; D014451:Ubiquinone / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D014466:Ultraviolet Rays
D004791:Enzyme Inhibitors; D006912:Hydroxyquinolines; D009097:Multienzyme Complexes; D010420:Pentanes; D011809:Quinones; D014451:Ubiquinone; C001333:2-(n-heptyl)-4-hydroxyquinoline N-oxide; C033353:pentane; D001728:Dicumarol; D010088:Oxidoreductases; C022691:succinate oxidase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases