Reaction: germacra-1(10),4,11(13)-trien-12-oate + [reduced NADPHhemoprotein reductase] + O2 = 8β-hydroxygermacra-1(10),4,11(13)-trien-12-oate + [oxidized NADPHhemoprotein reductase] + H2O
For diagram of reaction click here.
Glossary: germacra-1(10),4,11(13)-trien-12-oate = germacrene A acid
8β-hydroxygermacra-1(10),4,11(13)-triene-12-oate = 8β-hydroxygermacrene A acid
inunolide = germacra-1(10),4,11(13)-trien-12,8β-lactone
8-epi-inunolide = germacra-1(10),4,11(13)-trien-12,8α-lactone
Other name(s): HaG8H; CYP71BL1; CYP71BL6
Systematic name: germacra-1(10),4,11(13)-trien-12-oate,[reduced NADPHhemoprotein reductase]:oxygen oxidoreductase (8β-hydroxylating)
Comments: A cytochrome P-450 (heme-thiolate) protein from the plant Helianthus annuus (common sunflower). The cyclisation of 8β-hydroxygermacra-1(10),4,11(13)-triene-12-oate to inunolide (12,8β) does not seem to occur spontaneously. The enzyme from Inula hupehensis also forms some 8α-hydroxygermacra-1(10),4,11(13)-triene-12-oate, which spontaneously cyclises to 8-epi-inunolide (12,8α) (cf. EC 188.8.131.52 8-epi-inunolide synthase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
1. Frey, M., Schmauder, K., Pateraki, I. and Spring, O. Biosynthesis of eupatolide-A metabolic route for sesquiterpene lactone formation involving the P450 enzyme CYP71DD6. ACS Chem. Biol. 13 (2018) 1536-1543. [PMID: 29758164]
2. Gou, J., Hao, F., Huang, C., Kwon, M., Chen, F., Li, C., Liu, C., Ro, D.K., Tang, H. and Zhang, Y. Discovery of a non-stereoselective cytochrome P450 catalyzing either 8α- or 8β-hydroxylation of germacrene A acid from the Chinese medicinal plant, Inula hupehensis. Plant J. 93 (2018) 92-106. [PMID: 29086444]