Abstract: This chapter discusses the determination of nitrate reductase from higher plants. Nitrate reductase is capable of utilizing reduced pyridinenucleotides, flavin, or benzyl viologen as electron donors for the reduction of nitrate to nitrite. These reductants can be added in the reduced form or generated enzymatically in the reaction mixture. Because the NADH-dependent nitrate reductase is most prevalent in plants, NADH has been the most commonly employed reductant. Enzyme activity is usually measured by the colorimetric determination of the nitrite formed during a timed incubation period at a fixed temperature, regardless of electron donor used. The activity can also be measured by following the oxidation of the pyridine nucleotides at 340 nm. The relative merits and limitations of these methods are discussed in the chapter. The stoichiometric relationship between nitrite produced and pyridine nucleotide or flavin oxidized is also established. In all purification methods so far developed, chromatography on calcium phosphate gel features prominently, used either in batches or in columns. Nitrate reductase precipitates with exceptional ease on addition of ammonium sulfate, and this step may be worth using more than once in a purification method.
Publication Year: 1971
Publication Date: 1971-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
Access and Citation
Cited By Count: 326
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