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)
For diagram of reaction click here.
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.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
References:
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]