ISSN:
1573-5176
Keywords:
Nitrate reductase
;
in situ enzymatic activity
;
Dunaliella viridis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract An in situ method for measuring nitrate reductase (NR) activity in Dunaliella viridis was optimized in terms of incubation time, concentration of KNO3, permeabilisers (1-propanol and toluene), pH, salinity, and reducing power (glucose and NADH). NR activity was measured by following nitrite production and was best assayed with 50 mM KNO3, 1.2 mM NADH, 5% 1-propanol (v/v), at pH 8.5. The estimated half-saturation constant (Ks) for KNO3 was 5 mM. Glucose had no effect as external reducing power source, and NADH concentrations 〉1.2 mM inhibited NR activity. Nitrite production was linear up to 20 min; longer incubation did not lead to higher nitrate reduction. The use of the optimized assay predicted the rate of NO 3 − removal from the external medium by D. viridis with high degree of precision.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007978512458
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