Reaction: 2-nitrophenol + 2 NADPH + 2 H+ + O2 = catechol + nitrite + 2 NADP+ + H2O
(1a) 2-nitrophenol + NADPH + H+ + O2 = 1,2-benzoquinone + nitrite + NADP+ + H2O
(1b) 1,2-benzoquinone + NADPH + H+ = catechol + NADP+ (spontaneous)
For diagram of reaction click here
Other name(s): 2-nitrophenol oxygenase; nitrophenol oxygenase; OnpA
Systematic name: 2-nitrophenol,NADPH:oxygen 2-oxidoreductase (2-hydroxylating, nitrite-forming)
Comments: Involved in the metabolism of nitro-aromatic compounds by bacteria. The enzyme contains a cytochrome b5 domain that is involved in the reaction, and binds FAD and heme b. It has been suggested that reaction (1b) is spontaneous only in vitro and is catalysed by a different enzyme (OnpB) in vivo.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, CAS registry number: 104520-84-5
References:
1. Zeyer, J., Kocher, H.P. and Timmis, N. Influence of para-substituents on the oxidative metabolism of o-nitrophenols by Pseudomonas putida B2. Appl. Environ. Microbiol. 52 (1986) 334-339. [PMID: 3752997]
2. Xiao, Y., Zhang, J.J., Liu, H. and Zhou, N.Y. Molecular characterization of a novel ortho-nitrophenol catabolic gene cluster in Alcaligenes sp. strain NyZ215. J. Bacteriol. 189 (2007) 6587-6593. [PMID: 17616586]
3. Xiao, Y., Liu, T.T., Dai, H., Zhang, J.J., Liu, H., Tang, H., Leak, D.J. and Zhou, N.Y. OnpA, an unusual flavin-dependent monooxygenase containing a cytochrome b5 domain. J. Bacteriol. 194 (2012) 1342-1349. [PMID: 22267507]