The Enzyme Database

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EC 1.14.11.9     
Accepted name: flavanone 3-dioxygenase
Reaction: a (2S)-flavan-4-one + 2-oxoglutarate + O2 = a (2R,3R)-dihydroflavonol + succinate + CO2
For diagram of flavonoid biosynthesis, click here and for diagram of naringenin derivatives biosynthesis, click here
Other name(s): naringenin 3-hydroxylase; flavanone 3-hydroxylase; flavanone 3β-hydroxylase; flavanone synthase I; (2S)-flavanone 3-hydroxylase; naringenin,2-oxoglutarate:oxygen oxidoreductase (3-hydroxylating); F3H; flavanone,2-oxoglutarate:oxygen oxidoreductase (3-hydroxylating)
Systematic name: (2S)-flavan-4-one,2-oxoglutarate:oxygen oxidoreductase (3-hydroxylating)
Comments: Requires Fe2+ and ascorbate. This plant enzyme catalyses an early step in the flavonoid biosynthesis pathway, leading to the production of flavanols and anthocyanins. Substrates include (2S)-naringenin, (2S)-eriodictyol, (2S)-dihydrotricetin and (2S)-pinocembrin. Some enzymes are bifuctional and also catalyse EC 1.14.20.6, flavonol synthase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 75991-43-4
References:
1.  Forkmann, G., Heller, W. and Grisebach, H. Anthocyanin biosynthesis in flowers of Matthiola incana flavanone 3- and flavonoid 3′-hydroxylases. Z. Naturforsch. C: Biosci. 35 (1980) 691–695.
2.  Charrier, B., Coronado, C., Kondorosi, A. and Ratet, P. Molecular characterization and expression of alfalfa (Medicago sativa L.) flavanone-3-hydroxylase and dihydroflavonol-4-reductase encoding genes. Plant Mol. Biol. 29 (1995) 773–786. [PMID: 8541503]
3.  Pelletier, M.K. and Shirley, B.W. Analysis of flavanone 3-hydroxylase in Arabidopsis seedlings. Coordinate regulation with chalcone synthase and chalcone isomerase. Plant Physiol. 111 (1996) 339–345. [PMID: 8685272]
4.  Wellmann, F., Matern, U. and Lukačin, R. Significance of C-terminal sequence elements for Petunia flavanone 3β-hydroxylase activity. FEBS Lett. 561 (2004) 149–154. [DOI] [PMID: 15013767]
5.  Jin, Z., Grotewold, E., Qu, W., Fu, G. and Zhao, D. Cloning and characterization of a flavanone 3-hydroxylase gene from Saussurea medusa. DNA Seq 16 (2005) 121–129. [DOI] [PMID: 16147863]
6.  Shen, G., Pang, Y., Wu, W., Deng, Z., Zhao, L., Cao, Y., Sun, X. and Tang, K. Cloning and characterization of a flavanone 3-hydroxylase gene from Ginkgo biloba. Biosci Rep 26 (2006) 19–29. [DOI] [PMID: 16779664]
[EC 1.14.11.9 created 1983, modified 1989, modified 2004, modified 2016]
 
 
EC 1.14.11.23      
Transferred entry: flavonol synthase. Now EC 1.14.20.6, flavonol synthase
[EC 1.14.11.23 created 2004, deleted 2018]
 
 
EC 1.14.13.136      
Transferred entry: 2-hydroxyisoflavanone synthase. Now EC 1.14.14.87, 2-hydroxyisoflavanone synthase
[EC 1.14.13.136 created 2011, modified 2013, deleted 2018]
 
 
EC 1.14.14.87     
Accepted name: 2-hydroxyisoflavanone synthase
Reaction: (1) liquiritigenin + O2 + [reduced NADPH—hemoprotein reductase] = 2,4′,7-trihydroxyisoflavanone + H2O + [oxidized NADPH—hemoprotein reductase]
(2) (2S)-naringenin + O2 + [reduced NADPH—hemoprotein reductase] = 2,4′,5,7-tetrahydroxyisoflavanone + H2O + [oxidized NADPH—hemoprotein reductase]
For diagram of daidzein biosynthesis, click here
Glossary: liquiritigenin = 4′,7-dihydroxyflavanone
(2S)-naringenin = 4′,5,7-dihydroxyflavanone
2,4′,5,7-tetrahydroxyisoflavanone = 2-hydroxy-2,3-dihydrogenistein
Other name(s): CYP93C; IFS; isoflavonoid synthase
Systematic name: liquiritigenin, [reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (hydroxylating, aryl migration)
Comments: A cytochrome P-450 (heme thiolate) protein found in plants. The reaction involves the migration of the 2-phenyl group of the flavanone to the 3-position of the isoflavanone. The 2-hydroxyl group is derived from the oxygen molecule. EC 4.2.1.105, 2-hydroxyisoflavanone dehydratase, acts on the products with loss of water and formation of genistein and daidzein, respectively.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Kochs, G. and Grisebach, H. Enzymic synthesis of isoflavones. Eur. J. Biochem. 155 (1986) 311–318. [DOI] [PMID: 3956488]
2.  Hashim, M.F., Hakamatsuka, T., Ebizuka, Y. and Sankawa, U. Reaction mechanism of oxidative rearrangement of flavanone in isoflavone biosynthesis. FEBS Lett. 271 (1990) 219–222. [DOI] [PMID: 2226805]
3.  Steele, C. L., Gijzen, M., Qutob, D. and Dixon, R.A. Molecular characterization of the enzyme catalyzing the aryl migration reaction of isoflavonoid biosynthesis in soybean. Arch. Biochem. Biophys. 367 (1999) 146–150. [DOI] [PMID: 10375412]
4.  Sawada, Y., Kinoshita, K., Akashi, T., Aoki, T. and Ayabe, S. Key amino acid residues required for aryl migration catalysed by the cytochrome P450 2-hydroxyisoflavanone synthase. Plant J. 31 (2002) 555–564. [DOI] [PMID: 12207646]
5.  Sawada, Y. and Ayabe, S. Multiple mutagenesis of P450 isoflavonoid synthase reveals a key active-site residue. Biochem. Biophys. Res. Commun. 330 (2005) 907–913. [DOI] [PMID: 15809082]
[EC 1.14.14.87 created 2011 as EC 1.14.13.136, modified 2013, transferred 2018 to EC 1.14.14.87]
 
 
EC 1.14.14.162     
Accepted name: flavanone 2-hydroxylase
Reaction: a flavanone + [reduced NADPH—hemoprotein reductase] + O2 = a 2-hydroxyflavanone + [oxidized NADPH—hemoprotein reductase] + H2O
For diagram of licodione biosynthesis, click here
Other name(s): CYP93G2 (gene name); CYP93B1 (gene name); (2S)-flavanone 2-hydroxylase; licodione synthase
Systematic name: flavanone,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (2-hydroxylating)
Comments: A cytochrome P-450 (heme thiolate) plant enzyme that catalyses the 2-hydroxylation of multiple flavanones such as (2S)-naringenin, (2S)-eriodictyol, (2S)-pinocembrin, and (2S)-liquiritigenin. The products are meta-stable and exist in an equilibrium with open forms such as 1-(4-hydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propane-1,3-dione.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Otani, K., Takahashi, T., Furuya, T. and Ayabe, S. Licodione synthase, a cytochrome P450 monooxygenase catalyzing 2-hydroxylation of 5-deoxyflavanone, in cultured Glycyrrhiza echinata L. cells. Plant Physiol. 105 (1994) 1427–1432. [PMID: 12232298]
2.  Akashi, T., Aoki, T. and Ayabe, S. Identification of a cytochrome P450 cDNA encoding (2S)-flavanone 2-hydroxylase of licorice (Glycyrrhiza echinata L.; Fabaceae) which represents licodione synthase and flavone synthase II. FEBS Lett. 431 (1998) 287–290. [DOI] [PMID: 9708921]
3.  Du, Y., Chu, H., Chu, I.K. and Lo, C. CYP93G2 is a flavanone 2-hydroxylase required for C-glycosylflavone biosynthesis in rice. Plant Physiol. 154 (2010) 324–333. [PMID: 20647377]
[EC 1.14.14.162 created 2018. EC 1.14.14.140 created 2004 as EC 1.14.13.87, transferred 2018 to EC 1.14.14.140, transferred 2018 to EC 1.14.14.162]
 
 
EC 1.14.20.6     
Accepted name: flavonol synthase
Reaction: a dihydroflavonol + 2-oxoglutarate + O2 = a flavonol + succinate + CO2 + H2O
For diagram of flavonoid biosynthesis, click here, for diagram of kaempferol biosynthesis, click here and for diagram of myricetin biosynthesis, click here
Other name(s): FLS (gene name)
Systematic name: dihydroflavonol,2-oxoglutarate:oxygen oxidoreductase
Comments: In addition to the desaturation of (2R,3R)-dihydroflavonols to flavonols, the enzyme from Citrus unshiu (satsuma mandarin) also has a non-specific activity that trans-hydroxylates the flavanones (2S)-naringenin and the unnatural (2R)-naringenin at C-3 to kaempferol and (2R,3R)-dihydrokaempferol, respectively [2]. Requires Fe2+.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 146359-76-4
References:
1.  Wellmann, F., Lukačin, R., Moriguchi, T., Britsch, L., Schiltz, E. and Matern, U. Functional expression and mutational analysis of flavonol synthase from Citrus unshiu. Eur. J. Biochem. 269 (2002) 4134–4142. [DOI] [PMID: 12180990]
2.  Lukačin, R., Wellmann, F., Britsch, L., Martens, S. and Matern, U. Flavonol synthase from Citrus unshiu is a bifunctional dioxygenase. Phytochemistry 62 (2003) 287–292. [DOI] [PMID: 12620339]
3.  Martens, S., Forkmann, G., Britsch, L., Wellmann, F., Matern, U. and Lukačin, R. Divergent evolution of flavonoid 2-oxoglutarate-dependent dioxygenases in parsley. FEBS Lett. 544 (2003) 93–98. [DOI] [PMID: 12782296]
4.  Turnbull, J.J., Nakajima, J., Welford, R.W., Yamazaki, M., Saito, K. and Schofield, C.J. Mechanistic studies on three 2-oxoglutarate-dependent oxygenases of flavonoid biosynthesis: anthocyanidin synthase, flavonol synthase, and flavanone 3β-hydroxylase. J. Biol. Chem. 279 (2004) 1206–1216. [DOI] [PMID: 14570878]
[EC 1.14.20.6 created 2004 as EC 1.14.11.23, transferred 2018 to EC 1.14.20.6]
 
 
EC 2.1.1.232     
Accepted name: naringenin 7-O-methyltransferase
Reaction: S-adenosyl-L-methionine + (2S)-naringenin = S-adenosyl-L-homocysteine + (2S)-sakuranetin
For diagram of naringenin methyl ethers biosynthesis, click here
Glossary: (2S)-naringenin = (2S)-5,7,4′-trihydroxyflavan-4-one
(2S)-sakuranetin = (2S)-5,4′-dihydroxy-7-methoxyflavan-4-one
Other name(s): NOMT
Systematic name: S-adenosyl-L-methionine:(2S)-5,7,4′-trihydroxyflavanone 7-O-methyltransferase
Comments: The enzyme is involved in the biosynthesis of the sakuranetin, an inducible defense mechanism of the plant Oryza sativa (Asian rice) against pathogen attack.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Rakwal, R., Agrawal, G.K., Yonekura, M. and Kodama, O. Naringenin 7-O-methyltransferase involved in the biosynthesis of the flavanone phytoalexin sakuranetin from rice (Oryza sativa L.). Plant Sci. 155 (2000) 213–221. [DOI] [PMID: 10814825]
[EC 2.1.1.232 created 2011]
 
 
EC 2.5.1.70     
Accepted name: naringenin 8-dimethylallyltransferase
Reaction: prenyl diphosphate + (–)-(2S)-naringenin = diphosphate + sophoraflavanone B
For diagram of sophoraflavanone G biosynthesis, click here
Glossary: dimethylallyl = prenyl = 3-methylbut-2-en-1-yl
(–)-(2S)-naringenin = (–)-(2S)-5,7-dihydroxy-2-(4-hydroxyphenyl)-2,3-dihydrochromen-4-one
sophoraflavanone B = (–)-(2S)-8-prenylnaringenin = (–)-(2S)-5,7-dihydroxy-2-(4-hydroxyphenyl)-8-(3-methylbut-2-en-1-yl)-2,3-dihydrochromen-4-one
Other name(s): N8DT; dimethylallyl-diphosphate:naringenin 8-dimethylallyltransferase
Systematic name: prenyl-diphosphate:naringenin 8-prenyltransferase
Comments: Requires Mg2+. This membrane-bound protein is located in the plastids [2]. In addition to naringenin, the enzyme can prenylate several other flavanones at the C-8 position, but more slowly. Along with EC 1.14.14.142 (8-dimethylallylnaringenin 2′-hydroxylase) and EC 2.5.1.71 (leachianone-G 2′′-dimethylallyltransferase), this enzyme forms part of the sophoraflavanone-G-biosynthesis pathway.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Yamamoto, H., Senda, M. and Inoue, K. Flavanone 8-dimethylallyltransferase in Sophora flavescens cell suspension cultures. Phytochemistry 54 (2000) 649–655. [DOI] [PMID: 10975499]
2.  Zhao, P., Inoue, K., Kouno, I. and Yamamoto, H. Characterization of leachianone G 2′′-dimethylallyltransferase, a novel prenyl side-chain elongation enzyme for the formation of the lavandulyl group of sophoraflavanone G in Sophora flavescens Ait. cell suspension cultures. Plant Physiol. 133 (2003) 1306–1313. [DOI] [PMID: 14551337]
[EC 2.5.1.70 created 2007]
 
 


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