EC |
1.17.9.1 |
Accepted name: |
4-methylphenol dehydrogenase (hydroxylating) |
Reaction: |
4-methylphenol + 4 oxidized azurin + H2O = 4-hydroxybenzaldehyde + 4 reduced azurin + 4 H+ (overall reaction) (1a) 4-methylphenol + 2 oxidized azurin + H2O = 4-hydroxybenzyl alcohol + 2 reduced azurin + 2 H+ (1b) 4-hydroxybenzyl alcohol + 2 oxidized azurin = 4-hydroxybenzaldehyde + 2 reduced azurin + 2 H+ |
Glossary: |
4-methylphenol = 4-cresol = p-cresol |
Other name(s): |
pchCF (gene names); p-cresol-(acceptor) oxidoreductase (hydroxylating); p-cresol methylhydroxylase; 4-cresol dehydrogenase (hydroxylating) |
Systematic name: |
4-methylphenol:oxidized azurin oxidoreductase (methyl-hydroxylating) |
Comments: |
This bacterial enzyme contains a flavin (FAD) subunit and a cytochrome c subunit. The flavin subunit abstracts two hydrogen atoms from the substrate, forming a quinone methide intermediate, then hydrates the latter at the benzylic carbon with a hydroxyl group derived from water. The protons are lost to the bulk solvent, while the electrons are passed to the heme on the cytochrome subunit, and from there to azurin, a small copper-binding protein that is co-localized with the enzyme in the periplasm. The first hydroxylation forms 4-hydroxybenzyl alcohol; a second hydroxylation converts this into 4-hydroxybenzaldehyde. |
Links to other databases: |
BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 66772-07-4 |
References: |
1. |
Hopper, D.J. and Taylor, D.G. The purification and properties of p-cresol-(acceptor) oxidoreductase (hydroxylating), a flavocytochrome from Pseudomonas putida. Biochem. J. 167 (1977) 155–162. [PMID: 588247] |
2. |
McIntire, W., Edmondson, D.E. and Singer, T.P. 8α-O-Tyrosyl-FAD: a new form of covalently bound flavin from p-cresol methylhydroxylase. J. Biol. Chem. 255 (1980) 6553–6555. [PMID: 7391034] |
3. |
Hopper, D.J., Jones, M.R. and Causer, M.J. Periplasmic location of p-cresol methylhydroxylase in Pseudomonas putida. FEBS Lett. 182 (1985) 485–488. [PMID: 3920077] |
4. |
Bossert, I.D., Whited, G., Gibson, D.T. and Young, L.Y. Anaerobic oxidation of p-cresol mediated by a partially purified methylhydroxylase from a denitrifying bacterium. J. Bacteriol. 171 (1989) 2956–2962. [DOI] [PMID: 2722739] |
5. |
Reeve, C.D., Carver, M.A. and Hopper, D.J. Stereochemical aspects of the oxidation of 4-ethylphenol by the bacterial enzyme 4-ethylphenol methylenehydroxylase. Biochem. J. 269 (1990) 815–819. [PMID: 1697166] |
6. |
Peters, F., Heintz, D., Johannes, J., van Dorsselaer, A. and Boll, M. Genes, enzymes, and regulation of para-cresol metabolism in Geobacter metallireducens. J. Bacteriol. 189 (2007) 4729–4738. [PMID: 17449613] |
7. |
Johannes, J., Bluschke, A., Jehmlich, N., von Bergen, M. and Boll, M. Purification and characterization of active-site components of the putative p-cresol methylhydroxylase membrane complex from Geobacter metallireducens. J. Bacteriol. 190 (2008) 6493–6500. [PMID: 18658262] |
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[EC 1.17.9.1 created 1983 as EC 1.17.99.1, modified 2001, modified 2011, modified 2015, transferred 2018 to EC 1.17.9.1] |
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