Na+ is translocated at NADH:quinone oxidoreductase segment in the respiratory chain of Vibrio alginolyticus.
In: The Journal of biological chemistry, Jg. 259 (1984-06-25), Heft 12, S. 7785
academicJournal
Zugriff:
The coupling site of the Na+ pump to the respiratory chain of Vibrio alginolyticus was examined using membrane fractions prepared from the wild type, Na+ pump-deficient mutants, and spontaneous revertant. NADH oxidase of the wild type and revertant specifically required NA+ for maximum activity, whereas Na+ was not essential for the NADH oxidase of mutants. Similar to the Na+ pump in whole cells, the Na+-dependent NADH oxidase in membranes had a pH optimum in the alkaline region. A respiratory inhibitor, 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO), inhibited the Na+-dependent NADH oxidase but had little effect on the NA+-independent activity of mutant membranes. NADH:quinone oxidoreductase was found to be the Na+-dependent HQNO-sensitive site of the NADH oxidase. In the wild type cells, HQNO was also found to cause a strong inhibition of the Na+ pump with little effect on the overall H+ extrusion by respiration. The inhibition of the Na+ pump by HQNO was overcome by oxidized, but not reduced, N,N,N',N'-tetra-methyl-p-phenylenediamine (TMPD). In the presence of oxidised TMPD, the electron flow NADH to oxygen seemed to bypass the HQNO-sensitive site and energize the Na+ pump. From these results, it was concluded that the Na+ pump is coupled to the respiratory chain at the step of NADH:quinone oxidoreductase.
Titel: |
Na+ is translocated at NADH:quinone oxidoreductase segment in the respiratory chain of Vibrio alginolyticus.
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Autor/in / Beteiligte Person: | Tokuda, H ; Unemoto, T |
Zeitschrift: | The Journal of biological chemistry, Jg. 259 (1984-06-25), Heft 12, S. 7785 |
Veröffentlichung: | 2021- : [New York, NY] : Elsevier Inc. on behalf of American Society for Biochemistry and Molecular Biology ; <i>Original Publication</i>: Baltimore, MD : American Society for Biochemistry and Molecular Biology, 1984 |
Medientyp: | academicJournal |
ISSN: | 0021-9258 (print) |
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