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EC 1.14.18.11 Details

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EC number

1.14.18.11

Accepted name

plant 4α-monomethylsterol monooxygenase

Reaction

24-methylidenelophenol + 6 ferrocytochrome b₅ + 3 O₂ + 6 H⁺ = 3β-hydroxyergosta-7,24(24¹)-dien-4α-carboxylate + 6 ferricytochrome b₅ + 4 H₂O (overall reaction);;(1a) 24-methylidenelophenol + 2 ferrocytochrome b₅ + O₂ + 2 H⁺ = 4α-(hydroxymethyl)ergosta-7,24(24¹)-dien-3β-ol + 2 ferricytochrome b₅ + H₂O;;(1b) 4α-(hydroxymethyl)ergosta-7,24(24¹)-dien-3β-ol + 2 ferrocytochrome b₅ + O₂ + 2 H⁺ = 4α-formylergosta-7,24(24¹)-dien-3β-ol + 2 ferricytochrome b₅ + 2 H₂O;;(1c) 4α-formylergosta-7,24(24¹)-dien-3β-ol + 2 ferrocytochrome b₅ + O₂ + 2 H⁺ = 3β-hydroxyergosta-7,24(24¹)-dien-4α-carboxylate + 2 ferricytochrome b₅ + H₂O

Other name(s)

SMO2 (gene name)

Systematic name

24-ethylidenelophenol,ferrocytochrome-b₅:oxygen oxidoreductase (C-4α-methyl-hydroxylating)

Comment

This plant enzyme catalyses a step in the biosynthesis of sterols. It acts on the methyl group of the 4α-methylated intermediates 24-ethylidenelophenol and 24-methylidenelophenol and catalyses three successive oxidations, turning it into a carboxyl group. The carboxylate is subsequently removed by EC 1.1.1.418, plant 3β-hydroxysteroid-4α-carboxylate 3-dehydrogenase (decarboxylating). Unlike the fungal/animal enzyme EC 1.14.18.9, 4α-methylsterol monooxygenase, this enzyme is not able to act on 4,4-dimethylated substrates. That activity, which occurs earlier in the pathway, is performed in plants by a second enzyme, EC 1.14.18.10, plant 4,4-dimethylsterol C-4α-methyl-monooxygenase.

History

created 2019

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

1.3 Acting on the CH-CH group of donors

1.4 Acting on the CH-NH₂ group of donors

1.4.1 With NAD⁺ or NADP⁺ as acceptor

1.4.2 With a cytochrome as acceptor

1.4.3 With oxygen as acceptor

1.4.4 With a disulfide as acceptor

1.4.5 With a quinone or other compound as acceptor

1.4.7 With an iron-sulfur protein as acceptor

1.4.9 With a copper protein as acceptor

1.4.98. undefined

1.4.99 With unknown physiological acceptors

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

1.12 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

1.14.1 With NADH or NADPH as one donor (deleted sub-subclass)

1.14.2 With ascorbate as one donor (deleted sub-subclass)

1.14.3 With reduced pteridine as one donor (deleted sub-subclass)

1.14.11 With 2-oxoglutarate as one donor, and incorporation of one atom of oxygen into each donor

1.14.12 With NADH or NADPH as one donor, and incorporation of two atoms of oxygen into the other donor

1.14.13 With NADH or NADPH as one donor, and incorporation of one atom of oxygen into the other donor

1.14.14 With reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen into the other donor

1.14.15 With reduced iron-sulfur protein as one donor, and incorporation of one atom of oxygen into the other donor

1.14.16 With reduced pteridine as one donor, and incorporation of one atom of oxygen into the other donor

1.14.17 With reduced ascorbate as one donor, and incorporation of one atom of oxygen into the other donor

1.14.18 With another compound as one donor, and incorporation of one atom of oxygen into the other donor

1.14.18.1 tyrosinase

1.14.18.2 CMP-N-acetylneuraminate monooxygenase

1.14.18.3 methane monooxygenase (particulate)

1.14.18.4 phosphatidylcholine 12-monooxygenase

1.14.18.5 sphingolipid C4-monooxygenase

1.14.18.6 4-hydroxysphinganine ceramide fatty acyl 2-hydroxylase

1.14.18.7 dihydroceramide fatty acyl 2-hydroxylase

1.14.18.8 7α-hydroxycholest-4-en-3-one 12α-hydroxylase

1.14.18.9 4α-methylsterol monooxygenase

1.14.18.10 plant 4,4-dimethylsterol C-4α-methyl-monooxygenase

1.14.18.11 plant 4α-monomethylsterol monooxygenase

1.14.18.12 2-hydroxy fatty acid dioxygenase

1.14.19 With oxidation of a pair of donors resulting in the reduction of O₂ to two molecules of water

1.14.20 With 2-oxoglutarate as one donor, and the other dehydrogenated

1.14.21 With NADH or NADPH as one donor, and the other dehydrogenated

1.14.99 Miscellaneous

1.14.99.1 prostaglandin-endoperoxide synthase

1.14.99.2 kynurenine 7,8-hydroxylase

1.14.99.3 heme oxygenase (biliverdin-producing)

1.14.99.4 progesterone monooxygenase

1.14.99.5 created 1972, modified 1986, modified 2000, deleted 2000

1.14.99.6 created 1972, modified 2000, deleted 2000

1.14.99.7 squalene monooxygenase

1.14.99.8 created 1972, deleted 1984

1.14.99.9 steroid 17α-monooxygenase

1.14.99.10 steroid 21-monooxygenase

1.14.99.11 estradiol 6β-monooxygenase

1.14.99.12 androst-4-ene-3,17-dione monooxygenase

1.14.99.13 created 1972, deleted 1984

1.14.99.14 progesterone 11α-monooxygenase

1.14.99.15 4-methoxybenzoate monooxygenase (O-demethylating)

1.14.99.16 created 1972, deleted 2002

1.14.99.17 created 1972, deleted 1976

1.14.99.18 created 1976, modified 1999, deleted 2003

1.14.99.19 plasmanylethanolamine desaturase

1.14.99.20 phylloquinone monooxygenase (2,3-epoxidizing)

1.14.99.21 Latia-luciferin monooxygenase (demethylating)

1.14.99.22 ecdysone 20-monooxygenase

1.14.99.23 3-hydroxybenzoate 2-monooxygenase

1.14.99.24 steroid 9α-monooxygenase

1.14.99.25 created 1986, deleted 2000

1.14.99.26 2-hydroxypyridine 5-monooxygenase

1.14.99.27 juglone 3-monooxygenase

1.14.99.28 linalool 8-monooxygenase

1.14.99.29 deoxyhypusine monooxygenase

1.14.99.30 carotene 7,8-desaturase

1.14.99.31 myristoyl-CoA 11-(E) desaturase

1.14.99.32 myristoyl-CoA 11-(Z) desaturase

1.14.99.33 Δ¹²-fatty acid dehydrogenase

1.14.99.34 monoprenyl isoflavone epoxidase

1.14.99.35 thiophene-2-carbonyl-CoA monooxygenase

1.14.99.36 β-carotene 15,15′-monooxygenase

1.14.99.37 taxadiene 5α-hydroxylase

1.14.99.38 cholesterol 25-monooxygenase

1.14.99.39 ammonia monooxygenase

1.14.99.40 5,6-dimethylbenzimidazole synthase

1.14.99.41 all-trans-8′-apo-β-carotenal 15,15′-oxygenase

1.14.99.42 zeaxanthin 7,8-dioxygenase

1.14.99.43 β-amyrin 24-hydroxylase

1.14.99.44 diapolycopene oxygenase

1.14.99.45 carotene ε-monooxygenase

1.14.99.46 pyrimidine oxygenase

1.14.99.47 (+)-larreatricin hydroxylase

1.14.99.48 heme oxygenase (staphylobilin-producing)

1.14.99.49 2-hydroxy-5-methyl-1-naphthoate 7-hydroxylase

1.14.99.50 γ-glutamyl hercynylcysteine S-oxide synthase

1.14.99.51 hercynylcysteine S-oxide synthase

1.14.99.52 L-cysteinyl-L-histidinylsulfoxide synthase

1.14.99.53 lytic chitin monooxygenase

1.14.99.54 lytic cellulose monooxygenase (C1-hydroxylating)

1.14.99.55 lytic starch monooxygenase

1.14.99.56 lytic cellulose monooxygenase (C4-dehydrogenating)

1.14.99.57 heme oxygenase (mycobilin-producing)

1.14.99.58 heme oxygenase (biliverdin-IX-β and δ-forming)

1.14.99.59 tryptamine 4-monooxygenase

1.14.99.60 3-demethoxyubiquinol 3-hydroxylase

1.14.99.61 cyclooctat-9-en-7-ol 5-monooxygenase

1.14.99.62 cyclooctatin synthase

1.14.99.63 β-carotene 4-ketolase

1.14.99.64 zeaxanthin 4-ketolase

1.14.99.65 4-amino-L-phenylalanyl-[CmlP-peptidyl-carrier-protein] 3-hydroxylase

1.14.99.66 [histone H3]-N⁶,N⁶-dimethyl-L-lysine⁴ FAD-dependent demethylase

1.14.99.67 α-N-dichloroacetyl-p-aminophenylserinol N-oxygenase

1.14.99.68 4-aminobenzoate N-oxygenase

1.14.99.69 tRNA 2-(methylsulfanyl)-N⁶-isopentenyladenosine³⁷ hydroxylase

1.15 Acting on superoxide as acceptor

1.16 Oxidizing metal ions

1.17 Acting on CH or CH₂ groups

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

1.21 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

1.97.1 Sole sub-subclass for oxidoreductases that do not belong in the other subclasses

1.98 Enzymes using H₂ as reductant (deleted subclass)

1.99 Other enzymes using O₂ as oxidant (deleted subclass)

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Release 2023.1 (January 2023)