IUBMB Enzyme Nomenclature


Accepted name: 7-epi-iridoid synthase

Reaction: (R)-8-oxocitronellyl enol + NADP+ = (6E)-8-oxogeranial + NADPH + H+

Glossary: (R)-8-oxocitronellyl enol = (2E,6R,7E)-8-hydroxy-2,6-dimethylocta-2,7-dienal

Other name(s): AmISY

Systematic name: (R)-8-oxocitronellyl enol:NADP+ oxidoreductase

Comments: The enzyme, characterized from the plant Antirrhinum majus (snapdragon), is involved in biosynthesis of 7-epi-iridoids such as antirrhinoside. The enzyme catalyses the stereospecific reduction of 8-oxogeranial, forming an unstable product that in the absence of additional cylases undergoes spontaneous cyclization to (–)-cis,trans-nepetalactol. cf. EC, (S)-8-oxocitronellyl enol synthase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Kries, H., Kellner, F., Kamileen, M.O. and O'Connor, S.E. Inverted stereocontrol of iridoid synthase in snapdragon. J. Biol. Chem 292 (2017) 14659-14667. [PMID: 28701463]

2. Lichman, B.R., O'Connor, S.E. and Kries, H. Biocatalytic strategies towards [4+2] cycloadditions. Chemistry 25 (2019) 6864-6877. [PMID: 30664302]

[EC created 2019]

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