The Neurospora crassa assimilatory nitrite reductase (EC 1.6.6.4) catalyzes the NADPH-dependent reduction of nitrite to ammonia, a 6-electron transfer reaction. Highly purified preparations of this enzyme exhibit absorption spectra which suggest the presence of a heme component (wavelength maxima for oxidized senzyme: 390 and 578 nm). There is a close correspondence between nitrite reductase ac...

Nitrate simultaneously induced NADH- and NADPH-nitrate reductase activities in rice seedlings. Chloramphenicol, other organic nitro-compounds such as o-nitroaniline and 2,4-dinitrophenol and nitrite also induced nitrate reductase in rice seedlings. The nitrate- or nitrite-induced nitrate reductase could accept electrons more efficiently from NADH than NADPH. However, when this enzyme was induce...

A reduced nicotinamide adenine dinucleotide phosphate (NADPH)-specific enzyme from Escherichiu wti, isolated as a nitrite reductase, catalyzed the reductions of both nitrite and hydroxylamine to ammonia, and the ratio of the two activities remained constant during partial purification (1). The demonstration in the same species of an NADPH-specific enzyme catalyzing the reductions of hydroxylami...

Data regarding the role of oxygen in nitrite reduction are presented. In an NADPH-generating system including homogeneously purified ferredoxin-NADP reductase, ferredoxin (or flavodoxin) and nitrite reductase from the alga Bumilleriopsis filiformis, oxygen and nitrite can be reduced simultaneously. In air, rates of 1.2 mumol nitrite reduced-min-1-mg-1 nitrite reductase are obtained, which are p...

Reduction of nitrite by cell-free preparations of Anabaena cylindrica in the dark has been investigated. Nitrite-reducing activity was recovered in a supernatant fraction. The nitrite reductase system was partially purified by column chromatography on Sephadex G-75. NADPH could serve as an H-donor. NADH was completely inactive. The reduction required ferredoxin which mediated the transfer of el...

1. Enzyme systems from Cucurbita pepo have been shown to catalyse the reduction of nitrite and hydroxylamine to ammonia in yields about 90-100%. 2. Reduced benzyl viologen serves as an efficient electron donor for both systems. Activity of the nitrite-reductase system is directly related to degree of dye reduction when expressed in terms of the function for oxidation-reduction potentials, but a...

The addition of nitrite, the product of the reaction catalysed by nitrate reductase, to cell suspensions of the yeast Hansenula anomala caused a reversible inactivation of NADPH-dependent nitrate reductase activity. The haem- and Mo-dependent and Mo-dependent activities of nitrate reductase, determined with the non-physiological electron donors FMNH2 and reduced methyl viologen respectively, we...

Nitrate assimilation in many plants, algae, yeasts and bacteria is mediated by two enzymes, nitrate reductase (EC 1.6.6.2) and nitrite reductase (EC 1.7.7.1). They catalyse the stepwise reduction of nitrate to nitrite and nitrite to ammonia respectively. The nitrite reductase from an industrially important yeast, Candida utilis, has been purified to homogeneity. Purified nitrite reductase is a ...

We investigated the enzymatic reduction and oxidation of iron in M.magnetotacticum which synthesizes magnetite at room temperature. NADH-Fe(lI1) reductase with the molecular mass of 36kDa was purified from the bacterium. The enzyme was located in cytoplasm and utilized NADH and NADPH in the presence of FMN as reductant and showed maximum activity at pH 7.0. The Km for NADH and NADPH were about ...

Intercellular distribution of enzymes involved in amino nitrogen synthesis was studied in leaves of species representing three C(4) groups, i.e. Sorghum bicolor, Zea mays, Digitaria sanguinalis (NADP malic enzyme type); Panicum miliaceum (NAD malic enzyme type); and Panicum maximum (phosphoenolpyruvate carboxykinase type). Nitrate reductase, nitrite reductase, glutamine synthetase, and glutamat...