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EC 1.14.18.10 Details

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EC number

1.14.18.10

Accepted name

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

Reaction

24-methylidenecycloartanol + 6 ferrocytochrome b₅ + 3 O₂ + 6 H⁺ = 3β-hydroxy-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(24¹)-en-4α-carboxylate + 6 ferricytochrome b₅ + 4 H₂O (overall reaction);;(1a) 24-methylidenecycloartanol + 2 ferrocytochrome b₅ + O₂ + 2 H⁺ = 4α-(hydroxymethyl)-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(24¹)-en-3β-ol + 2 ferricytochrome b₅ + H₂O;;(1b) 4α-(hydroxymethyl)-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(24¹)-en-3β-ol + 2 ferrocytochrome b₅ + O₂ + 2 H⁺ = 4α-formyl-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(24¹)-en-3β-ol + 2 ferricytochrome b₅ + 2 H₂O;;(1c) 4α-formyl-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(24¹)-en-3β-ol + 2 ferrocytochrome b₅ + O₂ + 2 H⁺ = 3β-hydroxy-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(24¹)-en-4α-carboxylate + 2 ferricytochrome b₅ + H₂O

Other name(s)

SMO1 (gene name)

Systematic name

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

Comment

This plant enzyme catalyses a step in the biosynthesis of sterols. It acts on the 4α-methyl group of the 4,4-dimethylated intermediate 24-methylidenecycloartanol 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), which also catalyses the epimerization of the remaining 4β-methyl into the 4α position. Unlike the fungal/animal enzyme EC 1.14.18.9, 4α-methylsterol monooxygenase, this enzyme is not able to remove the methyl group from C-4-monomethylated substrates. That activity is performed in plants by a second enzyme, EC 1.14.18.11, plant 4α-monomethylsterol 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

1.5 Acting on the CH-NH group of donors

1.6 Acting on NADH or NADPH

1.6.1 With NAD⁺ or NADP⁺ as acceptor

1.6.2 With a heme protein as acceptor

1.6.3 With oxygen as acceptor

1.6.4 With a disulfide as acceptor (deleted sub-subclass)

1.6.5 With a quinone or similar compound as acceptor

1.6.6 With a nitrogenous group as acceptor

1.6.7 With an iron-sulfur protein as acceptor (deleted sub-subclass)

1.6.7.1 created 1972, deleted 1978

1.6.7.2 created 1972, deleted 1978

1.6.7.3 created 1978, deleted 1978

1.6.8 With a flavin as acceptor (deleted sub-subclass)

1.6.99 With unknown physiological acceptors

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

1.14.15.1 camphor 5-monooxygenase

1.14.15.2 camphor 1,2-monooxygenase

1.14.15.3 alkane 1-monooxygenase

1.14.15.4 steroid 11β-monooxygenase

1.14.15.5 corticosterone 18-monooxygenase

1.14.15.6 cholesterol monooxygenase (side-chain-cleaving)

1.14.15.7 choline monooxygenase

1.14.15.8 steroid 15β-monooxygenase

1.14.15.9 spheroidene monooxygenase

1.14.15.10 (+)-camphor 6-endo-hydroxylase

1.14.15.11 pentalenic acid synthase

1.14.15.12 pimeloyl-[acyl-carrier protein] synthase

1.14.15.13 pulcherriminic acid synthase

1.14.15.14 methyl-branched lipid ω-hydroxylase

1.14.15.15 cholestanetriol 26-monooxygenase

1.14.15.16 vitamin D₃ 24-hydroxylase

1.14.15.17 pheophorbide a oxygenase

1.14.15.18 calcidiol 1-monooxygenase

1.14.15.19 C-19 steroid 1α-hydroxylase

1.14.15.20 heme oxygenase (biliverdin-producing, ferredoxin)

1.14.15.21 zeaxanthin epoxidase

1.14.15.22 vitamin D 1,25-hydroxylase

1.14.15.23 chloroacetanilide N-alkylformylase

1.14.15.24 β-carotene 3-hydroxylase

1.14.15.25 p-cymene methyl-monooxygenase

1.14.15.26 toluene methyl-monooxygenase

1.14.15.27 β-dihydromenaquinone-9 ω-hydroxylase

1.14.15.28 cholest-4-en-3-one 26-monooxygenase [(25R)-3-oxocholest-4-en-26-oate forming]

1.14.15.29 cholest-4-en-3-one 26-monooxygenase [(25S)-3-oxocholest-4-en-26-oate forming]

1.14.15.30 3-ketosteroid 9α-monooxygenase

1.14.15.31 2-hydroxy-5-methyl-1-naphthoate 7-hydroxylase

1.14.15.32 pentalenene oxygenase

1.14.15.33 pikromycin synthase

1.14.15.34 20-oxo-5-O-mycaminosyltylactone 23-monooxygenase

1.14.15.35 6-deoxyerythronolide B hydroxylase

1.14.15.36 sterol 14α-demethylase (ferredoxin)

1.14.15.37 luteothin monooxygenase

1.14.15.38 N,N-dimethyl phenylurea N-demethylase

1.14.15.39 epi-isozizaene 5-monooxygenase

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

1.15 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

1.21.1 With NAD⁺ or NADP⁺ as acceptor

1.21.3 With oxygen as acceptor

1.21.4 With a disulfide as acceptor

1.21.98 With other, known, physiological acceptors

1.21.99 With unknown physiological acceptors

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)