ISSN:
1432-072X
Keywords:
Nitrogenase
;
Anabaena
;
Pyruvate: Ferredoxin Oxidoreductase
;
Blue-Green Alga
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Exogenous pyruvate added to cultures of the bluegreen alga, Anabaena cylindrica stimulated nitrogenase activity (measured by acetylene reduction) only in the dark under low pO2 (0.05 atmospheres). Under aerobic conditions or in the light, stimulation was absent and replaced by an inhibition of activity above 5 mM added pyruvate. The curve of nitrogenase activity versus oxygen concentration had a similar maximal value of ethylene production with or without added pyruvate, but in the presence of pyruvate this maximum occurred at 0.05 atmospheres O2, whilst in the absence of pyruvate the maximum occurred at 0.10 atmospheres O2. Malate, citrate, α-ketoglutarate, glucose and fructose were tested also, but none gave a similar effect to pyruvate. Addition of 14C-pyruvate and autoradiography indicated that exogenous pyruvate is metabolized through the interrupted Krebs cycle. These results are explained in terms of the activity of pyruvate: ferredoxin oxidoreductase and the ATP-induced oxygen sensitivity of nitrogenase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00447114
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