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MetaCyc Reaction:

Superclasses: Reactions Classified By Conversion TypeSimple ReactionsChemical Reactions
Reactions Classified By SubstrateSmall-Molecule Reactions

EC Number:

Enzymes and Genes:

Arabidopsis thaliana col: flavonol synthaseInferred from experiment: FLS
Citrus unshiu: flavonol synthase/flavanone 3-dioxygenaseInferred from experiment: FLS
Equisetum arvense: flavonol synthaseInferred from experiment: FLS
Fagopyrum tataricum: flavonol synthaseInferred from experiment: FLS1
Ginkgo biloba: anthocyanidin synthase/flavonol synthaseInferred from experiment: ANS/FLS

In Pathway: rutin biosynthesis, flavonoid biosynthesis (in equisetum), flavonol biosynthesis

Note that this reaction equation differs from the official Enzyme Commission reaction equation for this EC number, which can be found here .

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction in which it was curated.

Mass balance status: Balanced.

Direct generic reaction:
a dihydroflavonol + 2-oxoglutarate + oxygen → a flavonol + succinate + CO2 + H2O (

Enzyme Commission Primary Name: flavonol synthase

Standard Gibbs Free Energy (ΔrG in kcal/mol): -139.58595Inferred by computational analysis [Latendresse13]

Enzyme Commission Summary:
In addition to the desaturation of (2R,3R)-dihydroflavonols to flavonols, the enzyme from the satsuma orange Citrus unshiu also has a non-specific activity that trans-hydroxylates the flavanones (2S)-naringenin and the unnatural (2R)-naringenin at C-3 to kaempferol and (+)-dihydrokaempferol, respectively [Lukacin03]. Requires Fe2+.

Citations: [Wellmann02, Martens03, Turnbull04]

Gene-Reaction Schematic

Gene-Reaction Schematic

Unification Links: KEGG:R02160

Relationship Links: BRENDA:EC:, ENZYME:EC:, IUBMB-ExplorEnz:EC:


Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Lukacin03: Lukacin R, Wellmann F, Britsch L, Martens S, Matern U (2003). "Flavonol synthase from Citrus unshiu is a bifunctional dioxygenase." Phytochemistry 62(3);287-92. PMID: 12620339

Martens03: Martens S, Forkmann G, Britsch L, Wellmann F, Matern U, Lukacin R (2003). "Divergent evolution of flavonoid 2-oxoglutarate-dependent dioxygenases in parsley." FEBS Lett 544(1-3);93-8. PMID: 12782296

Turnbull04: Turnbull JJ, Nakajima J, Welford RW, Yamazaki M, Saito K, Schofield CJ (2004). "Mechanistic studies on three 2-oxoglutarate-dependent oxygenases of flavonoid biosynthesis: anthocyanidin synthase, flavonol synthase, and flavanone 3beta-hydroxylase." J Biol Chem 279(2);1206-16. PMID: 14570878

Wellmann02: Wellmann F, Lukacin R, Moriguchi T, Britsch L, Schiltz E, Matern U (2002). "Functional expression and mutational analysis of flavonol synthase from Citrus unshiu." Eur J Biochem 269(16);4134-42. PMID: 12180990

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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