ISSN:
1432-072X
Keywords:
Rhodopseudomonas capsulata
;
Continuous culture
;
Respiratory chain
;
Oxygen uptake
;
α-Ketoglutarate dehydrogenase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Assays were performed on the components of the respiratory chain enzyme complex and the citric acid cycle enzyme α-ketoglutarate dehydrogenase (EC 1.2.4.2) from membrane preparations of Rhodopseudomonas capsulata grown in continuous culture. Cells were grown photoheterotrophically then switched to a chemoheterotrophic growth mode. NADH-and succinate-dependent oxygen uptake activities and cytochrome c oxidase (EC 1.9.3.1) activity were 5–6-fold higher in chemotrophically grown cells. The activities of NADH dehydrogenase (EC 1.6.99.3) and succinate dehydrogenase (EC 1.3.99.1) did not differ greatly between the two growth modes, and it is suggested that in respiratory chain electron flow the cytochrome c oxidase segment catalyses the rate limiting step. In addition, a 5-fold increase in α-ketoglutarate dehydrogenase activity was observed after the transition from a phototrophic to chemotrophic growth mode. Oxidase and α-ketoglutarate dehydrogenase activities increased 3–4-fold in phototrophically growing cultures exposed to a low partial pressure of oxygen (50 Pa; 1 atmosphere = 1.013×105 Pa). The data suggest that this small amount of oxygen exerts a significant effect on aerobic bioenergetic enzymes, even during phototrophic growth of Rhodopseudomonas capsulata.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00407811
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