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EC 1.17.9.1 Details

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EC number

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⁺

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)

CAS registry number

66772-07-4

Comment

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.

History

created 1983 as EC 1.17.99.1, modified 2001, modified 2011, modified 2015, transferred 2018 to EC 1.17.9.1

EC Tree

1 Oxidoreductases

1.1 Acting on the CH-OH group of donors

1.2 Acting on the aldehyde or oxo group of donors

1.2.1 With NAD⁺ or NADP⁺ as acceptor

1.2.2 With a cytochrome as acceptor

1.2.3 With oxygen as acceptor

1.2.4 With a disulfide as acceptor

1.2.5 With a quinone or similar compound as acceptor

1.2.7 With an iron-sulfur protein as acceptor

1.2.98 With other, known, physiological acceptors

1.2.99 With unknown physiological acceptors

1.3 Acting on the CH-CH group of donors

1.4 Acting on the CH-NH₂ group of donors

1.5 Acting on the CH-NH group of donors

1.6 Acting on NADH or NADPH

1.7 Acting on other nitrogenous compounds as donors

1.8 Acting on a sulfur group of donors

1.9 Acting on a heme group of donors

1.10 Acting on diphenols and related substances as donors

1.11 Acting on a peroxide as acceptor

1.11.1 Peroxidases

1.11.2 Peroxygenases

1.12 Acting on hydrogen as donor

1.13 Acting on single donors with incorporation of molecular oxygen (oxygenases)

1.14 Acting on paired donors, with incorporation or reduction of molecular oxygen

1.15 Acting on superoxide as acceptor

1.16 Oxidizing metal ions

1.17 Acting on CH or CH₂ groups

1.17.1 With NAD⁺ or NADP⁺ as acceptor

1.17.2 With a cytochrome as acceptor

1.17.3 With oxygen as acceptor

1.17.4 With a disulfide as acceptor

1.17.5 With a quinone or similar compound as acceptor

1.17.7 With an iron-sulfur protein as acceptor

1.17.8 With a flavin as acceptor

1.17.9 With a copper protein as acceptor

1.17.9.1 4-methylphenol dehydrogenase (hydroxylating)

1.17.9.2 (+)-pinoresinol hydroxylase

1.17.98 With other, known, physiological acceptors

1.17.99 With unknown physiological acceptors

1.18 Acting on iron-sulfur proteins as donors

1.19 Acting on reduced flavodoxin as donor

1.20 Acting on phosphorus or arsenic in donors

1.20.1 With NAD⁺ or NADP⁺ as acceptor

1.20.2 With a cytochrome as acceptor

1.20.4 With disulfide as acceptor

1.20.9 With a copper protein as acceptor

1.20.98 With other, known, physiological acceptors

1.20.99 With unknown physiological acceptors

1.21 Catalysing the reaction X-H + Y-H = X-Y

1.22 Acting on halogen in donors

1.23 Reducing C-O-C group as acceptor

1.97 Other oxidoreductases

1.98 Enzymes using H₂ as reductant (deleted subclass)

1.99 Other enzymes using O₂ as oxidant (deleted subclass)