Accepted name: costunolide synthase
Reaction: germacra-1(10),4,11(13)-trien-12-oate + [reduced NADPH—hemoprotein reductase] + O2 = (+)-costunolide + [oxidized NADPH—hemoprotein reductase] + 2 H2O (overall reaction)
(1a) germacra-1(10),4,11(13)-trien-12-oate + [reduced NADPH—hemoprotein reductase] + O2 = 6α-hydroxygermacra-1(10),4,11(13)-trien-12-oate + [oxidized NADPH—hemoprotein reductase] + H2O
(1b) 6α-hydroxygermacra-1(10),4,11(13)-trien-12-oate = (+)-costunolide + H2O (spontaneous)
Other name(s): CYP71BL2
Systematic name: germacra-1(10),4,11(13)-trien-12-oate,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (6α-hydroxylating)
Comments: A cytochrome P-450 (heme-thiolate) protein from chicory plants. The enzyme hydroxylates carbon C-6 of germacra-1(10),4,11(13)-trien-12-oate to give 6α-hydroxygermacra-1(10),4,11(13)-trien-12-oate, which spontaneously cyclises to form the lactone ring.
1.  de Kraker, J.W., Franssen, M.C., Joerink, M., de Groot, A. and Bouwmeester, H.J. Biosynthesis of costunolide, dihydrocostunolide, and leucodin. Demonstration of cytochrome p450-catalyzed formation of the lactone ring present in sesquiterpene lactones of chicory. Plant Physiol. 129 (2002) 257–268. [PMID: 12011356]
[EC created 2011 as EC, transferred 2018 to EC]