ISSN:
1432-072X
Keywords:
Ammonium transport
;
Regulation
;
Rhodospirillum rubrum
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract An ammonium transport system in the phototrophic N2-fixing bacteriumRhodospirillum rubrum was characterized by using the uptake of14C-methylamine as a probe. Uptake showed saturation kinetics with an apparentK m =110 μM. It was competitively inhibited by ammonium (K i =7 μM). Uptake exhibited a narrow pH maximum around pH 7.0. Up to 200-fold gradients across the membrane were formed within 40–60 min. Gradient formation was inhibited by carbon starvation, azide or cyanide. Pre-accumulated methylamine was released by ammonium pulses to more than 80%, indicating only minor metabolization. The synthesis of the transport system was repressed by ammonium in high concentrations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00690822
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