the enzyme PNP monoxygenase is involved in the degradation of 4-nitrophenol, proposed pathway, overview. 4-Nitrophenol is converted to 4-nitrocatechol by a 4-nitrophenol 2-monooxygenase,
EC 1.14.13.29, of the enzyme, which is subsequently converted to 2-hydroxy-1,4-benzoquinone,
EC 1.14.13.166