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Appearance of the Na + ‐motive terminal oxidase in Bacillus FTU grown under three different conditions lowering the Δ\̄gm H+ level
Author(s) -
Semeykina Anna L.,
Skulachev Vladimir P.
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80407-8
Subject(s) - protonophore , chemistry , valinomycin , antiporter , cyanide , multicopper oxidase , potassium cyanide , oxidase test , nuclear chemistry , membrane transport , divalent , biochemistry , membrane , enzyme , biophysics , inorganic chemistry , laccase , biology , organic chemistry
The terminal oxidases and coupled Na + transport have been studied in intact cells and inside‐out subcellucar vesicles of alkalo‐ and halotolerant Bacillus FTU grown under different conditions. Cells grown at pH 7.5 are shown to possess a system or respiration‐dependent Na + transport which is (i) inhibited by protonophorous uncoupler and (ii) activated by Δψ‐discharging agent valinomycin, suggesting that the Na + transport is due to cooperation of the H + ‐motive oxidase and Na + /H + antiporter. On the other hand, growth under conditions lowering the Δ\̄gm H+ level, namely (i) pH 8.6, (ii) pH 7.5 in the presence of protonophore, and (iii) pH 7.5 in the presence of low cyanide concentrations results in appearance of terminal oxidase‐supported Na + transport which is stimulated by protonophores (the Na + ‐motive oxidase). In all three cases, the appearance of ascorbate (+ TMPD) oxidation resistant to low and sensitive to high cyanide concentrations was found to occur. It is concluded that not only alkaline pH but also other conditions which lower Δ\̄gm H+ can cause substitution of Na + for H + as a coupling ion.