Journal article

Publication year: 1993

Pages: 637-644

Journal: Phytochemistry

Volume number: 34

Issue number: 3

ISSN: 0031-9422

DOI Link: https://doi.org/10.1016/0031-9422(93)85331-K

Publisher: Elsevier

Abstract: 
Heterotrophic suspension cultures of wheat (Triticum aestivum L. cv Heines Koga II) were grown on media containing various amounts of nitrate and ammonium. Increasing the external ammonium concentration from 2 to 25 mM led to a 200% increase in the specific NADH-dependent glutamate synthase activity. In contrast, the specific glutamine synthetase activity decreased by 80%. High ammonium grown cells exhibited a two-10-fold elevation of glutamine, asparagine, alanine and ammonium, but up to an 80% decrease in malate, alpha-ketoglutarate, and nitrate pools. Cells exclusively supplied with ammonium nitrogen (nitrate starvation) ceased soluble protein synthesis and showed a specific increase in glutamate dehydrogenase activity. Regardless of changes in the nitrogen supply, the in vitro measured activity of NADH-dependent glutamate synthase was similar to the calculated in vivo rate of ammonium assimilation. The in vitro measured activity of glutamine synthetase was negatively related to the rate of ammonium assimilation, while the product of the in vitro measured activity of glutamine synthetase and the cellular concentration of ammonium was positively related to it. The results are discussed in terms of an in vivo regulation of glutamine synthetase activity by glutamine, alpha-ketoglutarate and the cytosolic concentration of ammonium.

Harvard Citation style: FRICKE, W. (1993) GLUTAMINE-SYNTHETASE AND GLUTAMATE SYNTHASE ACTIVITIES IN HIGH AMMONIUM GROWN WHEAT CELLS, Phytochemistry, 34(3), pp. 637-644. https://doi.org/10.1016/0031-9422(93)85331-K

APA Citation style: FRICKE, W. (1993). GLUTAMINE-SYNTHETASE AND GLUTAMATE SYNTHASE ACTIVITIES IN HIGH AMMONIUM GROWN WHEAT CELLS. Phytochemistry. 34(3), 637-644. https://doi.org/10.1016/0031-9422(93)85331-K