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Regulation of nitrate reductase in detached oat leaves by light and oxygen
Author(s) -
Kenis J. D.,
Trippi V. S.
Publication year - 1986
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.1399-3054.1986.tb03370.x
Subject(s) - nitrate reductase , darkness , avena , cycloheximide , chemistry , biochemistry , oxygen , nitrate , light intensity , enzyme , botany , biophysics , biology , protein biosynthesis , organic chemistry , physics , optics
Regulation of nitrate reductase (NR, EC 1.6.6.1) by oxygen concentration and light was studied in segments of oat ( Avena sativa L. cv. Suregrain) leaves, using the in vivo nitrate reductase assay. The activity of NR decreased after excision in either light or darkness; the addition of cycloheximide prevented this decrease. Treatments that increased tissue permeability (anoxia, Triton X‐100) also increased NR activity. There was in general less NR activity in the light than in the dark and also less under aerobic (21–100% O 2 ) than under anaerobic (0.3% O 2 ) conditions. Treatments with antioxidants improved the activity in the light, but only at high O 2 levels (21–100% O 2 ). The results suggest that NR may be regulated by inhibitory proteins synthesized in either light or darkness, by permeability changes and by light‐induced oxidations that occur when O 2 is present. Oxygen may control the activity by stimulating the synthesis of inhibitory proteins in the light and in the dark and by promoting oxidation of SH‐groups in the light.