Reaction: β-amyrin + 3 O2 + 3 [reduced NADPHhemoprotein reductase] = oleanolate + 3 [oxidized NADPHhemoprotein reductase] + 4 H2O (overall reaction)
(1a) β-amyrin + O2 + [reduced NADPHhemoprotein reductase] = erythrodiol + [oxidized NADPHhemoprotein reductase] + H2O
(1b) erythrodiol + O2 + [reduced NADPHhemoprotein reductase] = oleanolic aldehyde + [oxidized NADPHhemoprotein reductase] + 2 H2O
(1c) oleanolic aldehyde + O2 + [reduced NADPHhemoprotein reductase] = oleanolate + [oxidized NADPHhemoprotein reductase] + H2O
For diagram of reaction click here.
Other name(s): CYP716A52v2; CYP716A12; CYP16A75; β-amyrin 28-oxidase
Systematic name: β-amyrin,[reduced NADPHhemoprotein reductase]:oxygen oxidoreductase (28-hydroxylating)
Comments: A cytochrome P-450 (heme-thiolate) protein found in plants. The enzyme is involved in the biosynthesis of oleanane-type triterpenoids, such as ginsenoside Ro. The enzyme from Medicago truncatula (barrel medic) (CYP716A12) can also convert α-amyrin and lupeol to ursolic acid and betulinic acid, respectively. The enzyme from Maesa lanceolata (false assegai) (CYP16A75) does not catalyse the reaction to completion, resulting in accumulation of both intermediates.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
1. Fukushima, E.O., Seki, H., Ohyama, K., Ono, E., Umemoto, N., Mizutani, M., Saito, K. and Muranaka, T. CYP716A subfamily members are multifunctional oxidases in triterpenoid biosynthesis. Plant Cell Physiol 52 (2011) 2050-2061. [PMID: 22039103]
2. Han, J.Y., Kim, M.J., Ban, Y.W., Hwang, H.S. and Choi, Y.E. The involvement of β-amyrin 28-oxidase (CYP716A52v2) in oleanane-type ginsenoside biosynthesis in Panax ginseng. Plant Cell Physiol 54 (2013) 2034-2046. [PMID: 24092881]
3. Moses, T., Pollier, J., Faizal, A., Apers, S., Pieters, L., Thevelein, J.M., Geelen, D. and Goossens, A. Unraveling the triterpenoid saponin biosynthesis of the African shrub Maesa lanceolata. Mol. Plant 8 (2015) 122-135. [PMID: 25578277]