IUBMB Enzyme Nomenclature


Accepted name: 2,4,6-trichlorophenol monooxygenase

Reaction: 2,4,6-trichlorophenol + FADH2 + O2 = 6-chloro-2-hydroxy-1,4-benzoquinone + 2 Cl- + FAD (overall reaction)
(1a) 2,4,6-trichlorophenol + FADH2 + O2 = 2,6-dichloro-1,4-benzoquinone + Cl- + FAD + H2O
(1b) 2,6-dichloro-1,4-benzoquinone + H2O = 6-chloro-2-hydroxy-1,4-benzoquinone + Cl-

Other name(s): tcpA (gene name)

Systematic name: 2,4,6-trichlorophenol,FADH2:oxygen oxidoreductase (dechlorinating)

Comments: The enzyme, characterized from Cupriavidus pinatubonensis, participates in the degradation of 2,4,6-trichlorophenol, a compound that has been used for decades as a wood preservative. The enzyme is a multifunctional flavin-dependent monooxygenase that catalyses two different reactions to displace two chlorine atoms, a monooxygenase reaction followed by a hydrolysis reaction that takes advantage of the reactivity of the product of the first reaction, 2,6-dichloro-1,4-benzoquinone [2]. The large amount of FADH2 that is required is generated by a dedicated flavin reductase (TcpB). cf. EC, 3,5,6-trichloropyridin-2-ol monooxygenase.

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


1. Louie, T.M., Webster, C.M. and Xun, L. Genetic and biochemical characterization of a 2,4,6-trichlorophenol degradation pathway in Ralstonia eutropha JMP134. J. Bacteriol. 184 (2002) 3492-3500. [PMID: 12057943]

2. Xun, L. and Webster, C.M. A monooxygenase catalyzes sequential dechlorinations of 2,4,6-trichlorophenol by oxidative and hydrolytic reactions. J. Biol. Chem. 279 (2004) 6696-6700. [PMID: 14662756]

3. Hayes, R.P., Webb, B.N., Subramanian, A.K., Nissen, M., Popchock, A., Xun, L. and Kang, C. Structural and catalytic differences between two FADH2-dependent monooxygenases: 2,4,5-TCP 4-monooxygenase (TftD) from Burkholderia cepacia AC1100 and 2,4,6-TCP 4-monooxygenase (TcpA) from Cupriavidus necator JMP134. Int. J. Mol. Sci. 13 (2012) 9769-9784. [PMID: 22949829]

[EC created 2020, modified 2022]

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