MetaCyc Enzyme: 2-nitrophenol 2-monooxygenase

Species: Pseudomonas putida B2

2-nitrophenol 2-monooxygenase has been purified from Pseudomonas putida B2, a strain that is able to grow on 2-nitrophenol as the sole source of carbon and nitrogen [Zeyer84]. Experiments with a cell-free system showed that the enzyme is inducible by 2-nitrophenol, that the products were catechol and nitrite, and that NADPH is required. The specific activity in the cell-free system was 15 μmol/min/g protein [Zeyer84].

The enzyme was subsequently purified, and was shown to consist of a single polypeptide chain of 58 (gel filtration) or 65 (SDS-polyacrylamide gel) kDa [Zeyer88]. The enzyme was soluble, and consumed one molecule of molecular oxygen per molecule 2-nitrophenol converted.

Locations: cytosol

Molecular Weight of Polypeptide: 58.0 kD (experimental) [Zeyer88]

Gene-Reaction Schematic

Gene-Reaction Schematic

GO Terms:
Cellular Component:
GO:0005829 - cytosol [Zeyer88]

Created 23-Aug-2007 by Caspi R, SRI International

Enzymatic reaction of: 2-nitrophenol 2-monooxygenase

Inferred from experiment

EC Number:

2-nitrophenol + 2 NADPH + oxygen + 2 H+ → catechol + nitrite + 2 NADP+ + H2O

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.

In Pathways: 2-nitrophenol degradation

Activators (Allosteric): Mg2+ [Zeyer88], Mn2+ [Zeyer88] Inhibitors (Competitive): 2,4-dinitrophenol [Zeyer88]Kinetic Parameters:
Substrate Km (μM) Citations
2-nitrophenol 8.0 [Zeyer88]
NADPH 140.0 [Zeyer88]

pH(opt): 7.5-8 [Zeyer88]


Zeyer84: Zeyer, J., Kearney, P. C. (1984). "Degradation of o-Nitrophenol and m-Nitrophenol by a Pseudomonas putida." J. Agric. Food Chem. 32: 238-242.

Zeyer88: Zeyer J, Kocher HP (1988). "Purification and characterization of a bacterial nitrophenol oxygenase which converts ortho-nitrophenol to catechol and nitrite." J Bacteriol 170(4);1789-94. PMID: 3350791

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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