The Enzyme Database

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Accepted name: flavanoid 3′,5′-hydroxylase
Reaction: a flavanone + 2 NADPH + 2 H+ + 2 O2 = a 3′,5′-dihydroxyflavanone + 2 NADP+ + 2 H2O (overall reaction)
(1a) a flavanone + NADPH + H+ + O2 = a 3′-hydroxyflavanone + NADP+ + H2O
(1b) a 3′-hydroxyflavanone + NADPH + H+ + O2 = a 3′,5′-dihydroxyflavanone + NADP+ + H2O
For diagram of myricetin biosynthesis, click here, for diagram of the biosynthesis of naringenin derivatives, click here and for diagram of flavonoid biosynthesis, click here
Other name(s): flavonoid 3′,5′-hydroxylase
Systematic name: flavanone,NADPH:oxygen oxidoreductase
Comments: A heme-thiolate protein (P-450). The 3′,5′-dihydroxyflavanone is formed via the 3′-hydroxyflavanone. In Petunia hybrida the enzyme acts on naringenin, eriodictyol, dihydroquercetin (taxifolin) and dihydrokaempferol (aromadendrin). The enzyme catalyses the hydroxylation of 5,7,4′-trihydroxyflavanone (naringenin) at either the 3′ position to form eriodictyol or at both the 3′ and 5′ positions to form 5,7,3′,4′,5′-pentahydroxyflavanone (dihydrotricetin). The enzyme also catalyses the hydroxylation of 3,5,7,3′,4′-pentahydroxyflavanone (taxifolin) at the 5′ position, forming ampelopsin. NADH is not a good substitute for NADPH.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 94047-23-1
1.  Menting, J., Scopes, R.K. and Stevenson, T.W. Characterization of flavonoid 3′,5′-hydroxylase in microsomal membrane fraction of Petunia hybrida flowers. Plant Physiol. 106 (1994) 633–642. [PMID: 12232356]
2.  Shimada, Y., Nakano-Shimada, R., Ohbayashi, M., Okinaka, Y., Kiyokawa, S. and Kikuchi, Y. Expression of chimeric P450 genes encoding flavonoid-3′, 5′-hydroxylase in transgenic tobacco and petunia plants1. FEBS Lett. 461 (1999) 241–245. [PMID: 10567704]
3.  de Vetten, N., ter Horst, J., van Schaik, H.P., de Boer, A., Mol, J. and Koes, R. A cytochrome b5 is required for full activity of flavonoid 3′, 5′-hydroxylase, a cytochrome P450 involved in the formation of blue flower colors. Proc. Natl. Acad. Sci. USA 96 (1999) 778–783. [PMID: 9892710]
[EC created 2004]

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