Effect of oligomycin on NADH oxidation and its coupled phosphorylation with the particulate fraction from dark aerobically grown Rhodospirillum rubrum
✍ Scribed by Yamashita, J. ;Kamen, M. D. ;Horio, T.
- Publisher
- Springer-Verlag
- Year
- 1969
- Weight
- 569 KB
- Volume
- 66
- Category
- Article
- ISSN
- 0003-9276
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✦ Synopsis
NADH oxidation with the particulate fraction from dark aerobically grown Rhodospirillum rubrum is significantly stimulated by the addition of phosphate (Pi) and Mg ++, or Pi, Mg ++, ATP and the hexokinas~e-glucose system. Km values for Pi in NADH oxidation and phosphorylation are 10 -a ~ and 8 • 10 -4 ~, respectively. These Km values are almost the same as in corresponding photophosphorylation and oxidative phosphorylation catalyzed with chromatophores. As in the case of NADH oxidation with chromatophores, NADH oxidation with the particulate fraction has an optimal pH at 7.5 without additions, which is shifted to 6.9 by the addition of Pi and Mg ++, or Pi, Mg++; ATP and the hexokinase-glucose system. The optimal pI-I for coupled phosphorylation is 6.9. 10 ~g per ml of oligomycin can suppress stimulation of NADtt oxidation by Pi, or by the energy trapping system, and prevent the shift of optimal pH. The particulate fraction can catalyze Pi-incorporation into glucose-6-phosphate without externally added ATP, so that Pi-iacorporation is inhibited by oligomycin. From these findings, it is concluded that NADH oxidation in the particulate fraction is tightly coupled to phosphorylation.