Na(+)-translocating NADH-quinone reductase of marine and halophilic bacteria.
In: Journal of bioenergetics and biomembranes, Jg. 25 (1993-08-01), Heft 4, S. 385-91
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Zugriff:
The respiratory chain of marine and moderately halophilic bacteria requires Na+ for maximum activity, and the site of Na(+)-dependent activation is located in the NADH-quinone reductase segment. The Na(+)-dependent NADH-quinone reductase purified from marine bacterium Vibrio alginolyticus is composed of three subunits, alpha, beta, and gamma, with apparent M(r) of 52, 46, and 32 kDa, respectively. The FAD-containing beta-subunit reacts with NADH and reduces ubiquinone-1 (Q-1) by a one-electron transfer pathway to produce ubisemiquinones. In the presence of the FMN-containing alpha-subunit and the gamma-subunit, Q-1 is converted to ubiquinol-1 without the accumulation of free radicals. The reaction catalyzed by the alpha-subunit is strictly dependent on Na+ and is strongly inhibited by 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO), which is tightly coupled to the electrogenic extrusion of Na+. A similar type of Na(+)-translocating NADH-quinone reductase is widely distributed among marine and moderately halophilic bacteria. The respiratory chain of V. alginolyticus contains another NADH-quinone reductase which is Na+ independent and has no energy-transducing capacity. These two types of NADH-quinone reductase are quite different with respect to their mode of quinone reduction and their sensitivity toward NADH preincubation.
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Na(+)-translocating NADH-quinone reductase of marine and halophilic bacteria.
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Autor/in / Beteiligte Person: | Unemoto, T ; Hayashi, M |
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Zeitschrift: | Journal of bioenergetics and biomembranes, Jg. 25 (1993-08-01), Heft 4, S. 385-91 |
Veröffentlichung: | 1999- : New York, NY : Springer ; <i>Original Publication</i>: New York, Plenum Press., 1993 |
Medientyp: | academicJournal |
ISSN: | 0145-479X (print) |
DOI: | 10.1007/BF00762464 |
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