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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]

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, PDB

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]

4.2.1.105

Accepted name:

2-hydroxyisoflavanone dehydratase

Reaction:

(1) 2,4′,7-trihydroxyisoflavanone = daidzein + H₂O
(2) 2,4′,5,7-tetrahydroxyisoflavanone = genistein + H₂O

For diagram of biochanin A biosynthesis, click here and for diagram of daidzein biosynthesis, click here

Glossary:

daidzein = 4′,7-dihydroxyisoflavone
genistein = 4′,5,7-dihydroxyisoflavone

Other name(s):

2,7,4′-trihydroxyisoflavanone hydro-lyase; 2,7,4′-trihydroxyisoflavanone hydro-lyase (daidzein-forming)

Systematic name:

2,4′,7-trihydroxyisoflavanone hydro-lyase (daidzein-forming)

Comments:

Catalyses the final step in the formation of the isoflavonoid skeleton. The reaction also occurs spontaneously.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 166800-10-8

References:

1.	Hakamatsuka, T., Mori, K., Ishida, S., Ebizuka, Y and Sankawa, U. Purification of 2-hydroxyisoflavanone dehydratase from the cell cultures of Pueraria lobata. Phytochemistry 49 (1998) 497–505.

[EC 4.2.1.105 created 2004, modified 2013]