IUBMB Enzyme Nomenclature


Accepted name: germacrene A acid 8β-hydroxylase

Reaction: germacra-1(10),4,11(13)-trien-12-oate + [reduced NADPH—hemoprotein reductase] + O2 = 8β-hydroxygermacra-1(10),4,11(13)-trien-12-oate + [oxidized NADPH—hemoprotein 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 NADPH—hemoprotein 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 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]

[EC created 2018]

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