Nature 265, 373 - 375 (27 January 1977); doi:10.1038/265373a0

Model for the regulation of nitrate assimilation

LARRY P. SOLOMONSON & ANDREA M. SPEHAR

Department of Biochemistry, University of South Florida, College of Medicine, Tampa, Florida 33612

NITRATE assimilation is one of the two major biological processes by which inorganic nitrogen is converted to ammonia and thence to organic nitrogen. Photosynthetic organisms, with the possible exception of some blue-green algae and plants that have a symbiotic association with rogen-fixing bacteria, derive most of their nitrogen from nitrate¹. The rate-controlling and regulated step in the process of nitrate assimilation seems to be the conversion of nitrate to nitrite, catalysed by the enzyme nitrate reductase². There is a good correlation between the activity of this enzyme and the yield of grain protein in several cereal crops³⁻⁵. Nitrate arising from chemical fertilisers and industrial wastes is also a major factor contributing to the growth of algae and other microorganisms, leading to the eutrophication of lakes and streams. Thus, the control of nitrate assimilation can be important from the standpoint of both agricultural productivity and water resource management.

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