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A minimal model of light‐induced circadian rhythms of nitrate reductase activity in leaves of barley
Author(s) -
Lillo Cathrine,
Ruoff Peter
Publication year - 1984
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1984.tb02804.x
Subject(s) - darkness , hordeum vulgare , nitrate reductase , circadian rhythm , chemistry , biophysics , nitrate , rhythm , biochemistry , botany , biology , enzyme , poaceae , medicine , endocrinology , organic chemistry
Observed circadian rhythms of nitrate reductase (NR) (EC 1.6.6.1) activity in leaves of barley ( Hordeum vulgare L. cv. Herta) under continuous light conditions are described by a simple kinetic model. The oscillatory mechanism has been decomposed into the negative and positive feedback loops which are necessary according to present theories of chemical oscillating systems. Our results indicate that the decrease of NR activity in darkness can be considered as a reversible unimolecular conversion of the active form of NR into an inactive form, forming a negative stabilizing feedback loop. The light‐induced increase of NR activity is related to a positive destabilizing feedback loop. In our treatment this process is represented as an autocatalytical reaction.