ISSN:
1432-072X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary 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 hexokinase-glucose system. K m values for Pi in NADH oxidation and phosphorylation are 10−3 m and 8×10−4 m, respectively. These K m 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 pH for coupled phosphorylation is 6.9. 10 μg per ml of oligomycin can suppress stimulation of NADH 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-incorporation is inhibited by oligomycin. From these findings, it is concluded that NADH oxidation in the particulate fraction is tightly coupled to phosphorylation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00414586
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