Regulation of Asparaginase, Glutamine Synthetase, and Glutamate Dehydrogenase in Response to Medium Nitrogen Concentrations in a Euryhaline Chlamydomonas Species 1

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RESUMO

The ammonium assimilatory enzymes glutamine synthetase (EC 6.3.1.2) and glutamate dehydrogenase (EC 1.4.1.3) were investigated for a possible role in the regulation of asparaginase (EC 3.5.1.1) in a Chlamydomonas species isolated from a marine environment. Cells grown under nitrogen limitation (0.1 millimolar NH4+, NO3−, or l-asparagine) possessed 6 times the asparaginase activity and approximately one-half the protein of cells grown at high nitrogen levels (1.5 to 2.5 millimolar). Biosynthetic glutamine synthetase activity was 1.5 to 1.8 times greater in nitrogen-limited cells than cells grown at high levels of the three nitrogen sources.

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