Abstract
In an earlier paper (Cove, 1966) it was reported that the kinetics of appearance of nitrate reductase (NADPH–nitrate oxidoreductase, EC 1.6.6.3) on the addition of nitrate to a growing culture of Aspergillus nidulans were different in certain respects from those found for many Escherichia coli enzymes. When urea is used as an initial nitrogen source, a further difference is found: enzyme synthesis is no longer continuous. This interruption of synthesis does not appear to be due to synchronous cell division in the culture, nor to be due to accumulation of ammonia. Fluctuations in the intracellular concentration of nitrate, though appearing to be partly responsible for the discontinuity of enzyme syntheses, cannot account for all the observations. Two related hypotheses are put forward to explain this discontinuity of synthesis; each suggests that nitrate reductase is intimately concerned with its own synthesis. One possibility is that the enzyme when it is not in the form of a complex with nitrate is a co-repressor of its own synthesis, and the other that the enzyme is its own repressor.
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Selected References
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- COVE D. J., PATEMAN J. A. Independently segregating genetic loci concerned with nitrate reductase activity in Aspergillus nidulans. Nature. 1963 Apr 20;198:262–263. doi: 10.1038/198262a0. [DOI] [PubMed] [Google Scholar]
- Cove D. J., Coddington A. Purification of nitrate reductase and cytochrome c reductase from Aspergillus nidulans. Biochim Biophys Acta. 1965 Nov 22;110(2):312–318. doi: 10.1016/s0926-6593(65)80038-8. [DOI] [PubMed] [Google Scholar]
- Knutsen G. Induction of nitrite reductase in synchronized cultures of Chlorella pyrenoidosa. Biochim Biophys Acta. 1965 Jul 15;103(3):495–502. doi: 10.1016/0005-2787(65)90142-5. [DOI] [PubMed] [Google Scholar]
- PATEMAN J. A., COVE D. J., REVER B. M., ROBERTS D. B. A COMMON CO-FACTOR FOR NITRATE REDUCTASE AND XANTHINE DEHYDROGENASE WHICH ALSO REGULATES THE SYNTHESIS OF NITRATE REDUCTASE. Nature. 1964 Jan 4;201:58–60. doi: 10.1038/201058a0. [DOI] [PubMed] [Google Scholar]
- Pateman J. A., Rever B. M., Cove D. J. Genetic and biochemical studies of nitrate reduction in Aspergillus nidulans. Biochem J. 1967 Jul;104(1):103–111. doi: 10.1042/bj1040103. [DOI] [PMC free article] [PubMed] [Google Scholar]