IUBMB Enzyme Nomenclature


Accepted name: flavone synthase II

Reaction: a flavanone + [reduced NADPH—hemoprotein reductase] + O2 = a flavone + [oxidized NADPH—hemoprotein reductase] + 2 H2O

For diagram of reaction click here.

Other name(s): CYP93B16 (gene name); CYP93G1 (gene name); FNS II

Systematic name: flavanone,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (flavone-forming)

Comments: A cytochrome P-450 (heme-thiolate) protein found in plants. The rice enzyme channels flavanones to the biosynthesis of tricin O-linked conjugates. cf. EC, flavone synthase I.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Martens, S. and Forkmann, G. Cloning and expression of flavone synthase II from Gerbera hybrids. Plant J. 20 (1999) 611-618. [PMID: 10652133]

2. Fliegmann, J., Furtwangler, K., Malterer, G., Cantarello, C., Schuler, G., Ebel, J. and Mithofer, A. Flavone synthase II (CYP93B16) from soybean (Glycine max L.). Phytochemistry 71 (2010) 508-514. [PMID: 20132953]

3. Lam, P.Y., Zhu, F.Y., Chan, W.L., Liu, H. and Lo, C. Cytochrome P450 93G1 is a flavone synthase II that channels flavanones to the biosynthesis of tricin O-linked conjugates in rice. Plant Physiol. 165 (2014) 1315-1327. [PMID: 24843076]

[EC created 2018]

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