title: Enzymatic nitrate assay by a kinetic method employing Escherichia coli nitrate reductase.
abstract: An enzymatic assay system for nitrate employing the membrane-bound nitrate reductase (EC 1.7.99.4) of E. coli is described. Contrary to previous enzymatic assay systems, the present method is a kinetic one, i.e. the substrate, nitrate, is assayed by measuring the reaction rate of the nitrate reductase-catalyzed reaction. Based on the observation that the nitrate reductase-catalyzed reaction obeys pseudo-first order kinetics, a test system is described allowing the assay of nitrate at a concentration as low as 1 ppm. The relatively high Michaelis-Menten constant for nitrate (0.3 mM) of the E. coli nitrate reductase favours nitrate assay by the kinetic method.
mesh_terms: D002384:Catalysis; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008566:Membranes / Q000032:analysis; D050901:Nitrate Reductase; D009565:Nitrate Reductases; D009566:Nitrates / Q000032:analysis*; D012710:Serum Albumin, Bovine / Q000032:analysis
chemical_list: D009566:Nitrates; D012710:Serum Albumin, Bovine; D009565:Nitrate Reductases; D050901:Nitrate Reductase