scholarly journals Electron Transport Controls Glutamine Synthetase Activity in the Facultative Heterotrophic Cyanobacterium Synechocystis sp. PCC 6803

1995 ◽  
Vol 109 (3) ◽  
pp. 899-905 ◽  
Author(s):  
J. C. Reyes ◽  
J. L. Crespo ◽  
M. Garcia-Dominguez ◽  
F. J. Florencio
Keyword(s):  
Electron Transport ◽  
Glutamine Synthetase ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Synechocystis Sp ◽  
Pcc 6803

Respective effects of glucose and glutamine on the glutamine synthetase activity of human skin fibroblasts

1991 ◽  
Vol 102 (2) ◽  
Author(s):  
Th�ophile Soni ◽  
Claire Wolfrom ◽  
Samia Guerroui ◽  
Nicole Raynaud ◽  
Jos�phine Poggi ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Human Skin ◽  
Skin Fibroblasts ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Human Skin Fibroblasts

Control of nitrogen assimilation in Stichococcus bacillaris by growth conditions

1987 ◽  
Vol 65 (3) ◽  
pp. 432-437 ◽  
Author(s):  
Iftikhar Ahmad ◽  
Johan A. Hellebust
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Assimilation ◽  
Continuous Light ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Dark Cycle ◽  
Continuous Darkness ◽  
Cell Carbon ◽  
Stichococcus Bacillaris ◽  
Mixotrophic Conditions

Stichococcus bacillaris Naeg. (Chlorophyceae) grown on a 12 h light: 12 h dark cycle divides synchronously under photoautotrophic conditions and essentially nonsynchronously under mixotrophic conditions. Photoassimilation of carbon under photoautotrophic conditions was followed by a decline in cell carbon content during the dark period, whereas under mixotrophic conditions cell carbon increased throughout the light–dark cycle. The rates of nitrogen assimilation by cultures grown on either nitrate or ammonium declined sharply during the dark, and these declines were most pronounced under photoautotrophic conditions. Photoautotrophic cells synthesized glutamine synthetase and NADPH – glutamate dehydrogenase (GDH) exclusively in the light, whereas in mixotrophic cells about 20% of the total synthesis of these enzymes during one light–dark cycle occurred in the dark. NADH–GDH was synthesized almost continuously over the entire light–dark cycle. In the dark, both under photoautotrophic and mixotrophic conditions, the alga contained more than 50% of glutamine synthetase in an inactive form, which was reactivated in vitro in the presence of mercaptoethanol and in vivo after returning the cultures to the light. The thermal stability of glutamine synthetase activity was less in light-harvested cells than in dark-harvested cells. The inactivation of glutamine synthetase did not occur in cultures growing either heterotrophically in continuous darkness or photoautotrophically in continuous light. This enzyme appears to be under thiol control only in cells grown under alternating light–dark conditions, irrespective of whether this light regime results in synchronous cell division or not.

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