IUBMB Enzyme Nomenclature


Accepted name: brassinosteroid 6-oxygenase

Reaction: 6-deoxocastasterone + 2 O2 + 2 [reduced NADPH—hemoprotein reductase] = castasterone + 3 H2O + 2 [oxidized NADPH—hemoprotein reductase] (overall reaction)
(1a) 6-deoxocastasterone + O2 + [reduced NADPH—hemoprotein reductase] = 6α-hydroxy-6-deoxocastasterone + H2O + [oxidized NADPH—hemoprotein reductase]
(1b) 6α-hydroxy-6-deoxocastasterone + O2 + [reduced NADPH—hemoprotein reductase] = castasterone + 2 H2O + [oxidized NADPH—hemoprotein reductase]

For diagram of reaction, click here

Other name(s): CYP85A1 (gene name); CYP85A2 (gene name); brassinosteroid 6-oxidase

Systematic name: 6-deoxocastasterone,NADPH—hemoprotein reductase:oxygen 6-oxidoreductase (castasteron-forming)

Comments: This cytochrome P-450 (heme thiolate) plant enzyme catalyses the C-6 hydoxylation of several brassinosteroid biosynthesis intermediates, and the further oxidation of the hydroxyl group to an oxo group. Substrates include 6-deoxocastasterone, 6-deoxotyphasterol, 3-dehydro-6-deoxoteasterone, and 6-deoxoteasterone. The CYP85A2 isozyme of Arabidopsis thaliana (but not the CYP85A1 isozyme) also catalyses the activity of EC, brassinolide synthase.

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


1. Shimada, Y., Fujioka, S., Miyauchi, N., Kushiro, M., Takatsuto, S., Nomura, T., Yokota, T., Kamiya, Y., Bishop, G.J. and Yoshida, S. Brassinosteroid-6-oxidases from Arabidopsis and tomato catalyze multiple C-6 oxidations in brassinosteroid biosynthesis. Plant Physiol. 126 (2001) 770-779. [PMID: 11402205]

2. Perez-Espana, V.H., Sanchez-Leon, N. and Vielle-Calzada, J.P. CYP85A1 is required for the initiation of female gametogenesis in Arabidopsis thaliana. Plant Signal Behav. 6 (2011) 321-326. [PMID: 21364326]

[EC created 2022]

Return to EC 1.14.14 home page
Return to EC 1.14 home page
Return to EC 1 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page