IUBMB Enzyme Nomenclature


Accepted name: flavonoid 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

See diagram for reaction in ampelopsin or dihydrotricetin or taxifolin biosynthesis.

Other Name(s): F3'5'H; F3',5'H

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 plants. 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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