Nitrate reductase activity from filamentous, heterocyst-forming cyanobacteria showed a biphasic kinetic behavior with respect to nitrate as the variable substrate. Two kinetic components were detected, the first showing a higher affinity for nitrate (K(m), 0.05-0.25 mm) and a lower catalytic activity and the second showing a lower affinity for nitrate (K(m), 5-25 mm) and a higher (3- to 5-fold)...

An assay method is described for measurement of absolute concentrations of the molybdenum cofactor, based on complementation of the defective nitrate reductase ('apo nitrate reductase') in extracts of the nit-1 mutant of Neurospora crassa. A number of alternative methods are described for preparing, anaerobically, molybdenum-cofactor-containing solutions from sulphite oxidase, xanthine oxidase ...

We compared the nitrate reductase assay with the proportion method, which is considered the gold standard, in 57 Mycobacterium tuberculosis strains isolated from patients treated at the Federal University of Minas Gerais Hospital das Clínicas, located in the city of Belo Horizonte, Brazil. For rifampin and isoniazid, the sensitivity, specificity, and accuracy of the nitrate reductase assay were...

The plastoquinone antagonist 2,5-dibromothymoquinone was found to inhibit NO-3 reduction from NADH by the nitrate reductase complex from wheat. It accepts electrons from NADH through the NADH dehydrogenase activity of the nitrate reductase. However, it does not inhibit the reduction of 2,6-dichlorophenol-indophenol by the enzyme. This suggests that the two compounds may be accepting electrons a...

Escherichia coli possesses two distinct nitrite reductase enzymes encoded by the nrfA and nirB operons. The expression of each operon is induced during anaerobic cell growth conditions and is further modulated by the presence of either nitrite or nitrate in the cells' environment. To examine how each operon is expressed at low, intermediate, and high levels of either nitrate or nitrite, anaerob...

Nitric oxide (NO) is a signaling and defense molecule of major importance in living organisms. In the model legume Medicago truncatula, NO production has been detected in the nitrogen fixation zone of the nodule, but the systems responsible for its synthesis are yet unknown and its role in symbiosis is far from being elucidated. In this work, using pharmacological and genetic approaches, we exp...

In this study, eight transformed Solanum tuberosum L. plants, affected in their nitrate assimilatory pathway by the introduction of a tobacco nitrate reductase gene (Nia2), were cultivated in glasshouse conditions at INRA Ploudaniel (West Brittany, France). Two irrigation regimes were compared and plants were sampled at four stages of vegetation. Yield, tuber dry matter content, total nitrogen ...

A nitrate uptake system is induced (along with nitrate reductase) when NH(4) (+)-grown Penicillium chrysogenum is incubated with inorganic nitrate in synthetic medium in the absence of NH(4) (+). Nitrate uptake and nitrate reduction are probably in steady state in fully induced mycelium, but the ratios of the two activities are not constant during the induction period. Substrate concentrations ...

Propionibacterium acnes P13 was isolated from human feces. The bacterium produced a particulate nitrate reductase and a soluble nitrite reductase when grown with nitrate or nitrite. Reduced viologen dyes were the preferred electron donors for both enzymes. Nitrous oxide reductase was never detected. Specific growth rates were increased by nitrate during growth in batch culture. Culture pH stron...