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Nitrate Reduction in Different Grass Species
Author(s) -
DUSKY JOAN A.,
GALITZ DONALD S.
Publication year - 1977
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.1399-3054.1977.tb04039.x
Subject(s) - nitrate reductase , substrate (aquarium) , chemistry , extraction (chemistry) , enzyme , cysteine , reductase , in vivo , nitrate , biochemistry , oxidoreductase , chromatography , biology , ecology , microbiology and biotechnology , organic chemistry
Optimal extraction conditions, assay conditions, and levels of nit rate reductase activity (NRA) were determined for eight forage grass species adaptable to growing conditions in western North Dakota. Optimal pH for extraction of the enzyme nitrate reductase (NADH: nitrate oxidoreductase) for these species ranged from 7.0 to 9.5, whereas assay pH was 7.6 in all eight species. Substrate concentrations ranged from 1.0 to 10.0 m M for maximum NRA with higher concentrations (100 m M ) significantly inhibiting NRA. The enzyme was NADH 2 (0.1 to 0.2 m M for maximum activity) specific. Enhancement of maximum activity with the addition of cysteine during extraction was species dependent; six species required high cysteine concentrations between 5 m M and 10 m M and one species required only a 2.5 m M concentration. The degree of sulfhydryl protection offered by cysteine also varied. Comparisons were made between in vivo and in vitro assay methods. Ratios of in vitro to in vivo NRA ranged from 2.2. to 10.8. Use of bovine serum albumin as a protein stabilizer during extraction increased the measurable NRA in some species. Applications of nitrate reductase assay techniques to field work will be discussed.