Determination of nitrate reductase activity in different strains of Rhizobium japonicum
1989
Popovic, M. | Popovic, J. | Saric, M. | Gasic, O. (Prirodno-matematicki fakultet, Novi Sad (Yugoslavia))
Nitrate reductase activity was determined in the present paper in 12 strains of Rhizobium japonicum under different nitrogen concentrations in the reaction mixture and under different enzyme induction times. It was found that nitrate reductase (NR) activities in the examined strains were very different each other and ranged from 0 in the strain Rh-2/1 to 334n moles NO2 mg -1 proteins h-1 in Rh-D343. The highest NR activity for most of the investigated strains was observed under the nitrogen concentration of 1 mM KNO3 in the reaction mixture, whereas higher concentrations (2 and 3 mM KNO3) inhibited the enzyme activity. NR activities ranged from 31-216 n moles NO2 mg-1 proteins h-1 for the treatment of different induction times among which the time of 10 min was optimal. Received December 17th, 1989; Accepted Jannuary 16th, 1990
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