IUBMB Enzyme Nomenclature


Accepted name: brassinolide synthase

Reaction: castasterone + O2 + [reduced NADPH—hemoprotein reductase] = brassinolide + 2 H2O + [oxidized NADPH—hemoprotein reductase]

For diagram of reaction, click here

Other name(s): CYP85A2 (gene name); CYP85A3 (gene name)

Systematic name: castasterone,NADPH—hemoprotein reductase:oxygen oxidoreductase (lactonizing, brassinolide-forming)

Comments: This cytochrome P-450 (heme thiolate) plant enzyme catalyses the latonization of several brassinosteroids, including castasterone, teasterone, and typhasterol. The CYP85A2 enzyme of Arabidopsis thaliana also catalyses the activity of EC, brassinosteroid 6-oxygenase.

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


1. Nomura, T., Kushiro, T., Yokota, T., Kamiya, Y., Bishop, G.J. and Yamaguchi, S. The last reaction producing brassinolide is catalyzed by cytochrome P-450s, CYP85A3 in tomato and CYP85A2 in Arabidopsis. J. Biol. Chem. 280 (2005) 17873-17879. [PMID: 15710611]

2. Kim, T.W., Hwang, J.Y., Kim, Y.S., Joo, S.H., Chang, S.C., Lee, J.S., Takatsuto, S. and Kim, S.K. Arabidopsis CYP85A2, a cytochrome P450, mediates the Baeyer-Villiger oxidation of castasterone to brassinolide in brassinosteroid biosynthesis. Plant Cell 17 (2005) 2397-2412. [PMID: 16024588]

3. Katsumata, T., Hasegawa, A., Fujiwara, T., Komatsu, T., Notomi, M., Abe, H., Natsume, M. and Kawaide, H. Arabidopsis CYP85A2 catalyzes lactonization reactions in the biosynthesis of 2-deoxy-7-oxalactone brassinosteroids. Biosci. Biotechnol. Biochem. 72 (2008) 2110-2117. [PMID: 18685225]

[EC created 2022]

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