Nitronate monooxygenase that uses molecular oxygen to catalyze the oxidative denitrification of alkyl nitronates. Acts on propionate 3-nitronate (P3N), the presumed physiological substrate. Probably functions in the detoxification of P3N, a metabolic poison produced by plants and fungi as a defense mechanism. H2O + 3 O2 + 3 propionate 3-nitronate = 3 3-oxopropanoate + 3 H(+) + H2O2 + 2 nitrate + nitrite Binds 1 FMN per subunit. P3N is a potent irreversible inhibitor of the key enzyme succinate dehydrogenase in the Krebs cycle and electron transport chain. P3N has been shown to be a toxic metabolite to bacteria, plants, fungi, mammals or any organism that uses succinate dehydrogenase. Belongs to the nitronate monooxygenase family. NMO class I subfamily.