IUBMB Enzyme Nomenclature


Accepted name: toluene 2-monooxygenase

Reaction: (1) toluene + NADH + H+ + O2 = 2-methylphenol + NAD+ + H2O
(2) 2-methylphenol + NADH + H+ + O2 = 3-methylcatechol + NAD+ + H2O

Other name(s): tomA1/2/3/4/5 (gene names); toluene ortho-monooxygenase

Systematic name: toluene,NADH:oxygen oxidoreductase (2,3-dihydroxylating)

Comments: The enzyme, characterized from the bacterium Burkholderia cepacia, belongs to a class of nonheme, oxygen-dependent diiron enzymes. It contains a hydroxylase component with two binuclear iron centers, an NADH-oxidoreductase component containing FAD and a [2Fe-2S] iron-sulfur cluster, and a third component involved in electron transfer between the hydroxylase and the reductase. The enzyme dihydroxylates its substrate in two sequential hydroxylations, initially forming 2-methylphenol, which is hydroxylated to 3-methylcatechol.

Links to other databases: BRENDA, EXPASY, ExplorEnz, KEGG, MetaCyc, CAS registry number:


1. Newman, L.M. and Wackett, L.P. Purification and characterization of toluene 2-monooxygenase from Burkholderia cepacia G4. Biochemistry 34 (1995) 14066-14076. [PMID: 7578004]

2. Yeager, C.M., Bottomley, P.J., Arp, D.J. and Hyman, M.R. Inactivation of toluene 2-monooxygenase in Burkholderia cepacia G4 by alkynes. Appl. Environ. Microbiol. 65 (1999) 632-639. [PMID: 9925593]

3. Canada, K.A., Iwashita, S., Shim, H. and Wood, T.K. Directed evolution of toluene ortho-monooxygenase for enhanced 1-naphthol synthesis and chlorinated ethene degradation. J. Bacteriol. 184 (2002) 344-349. [PMID: 11751810]

[EC created 2019]

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