IUBMB Enzyme Nomenclature


Accepted name: neopinone isomerase

Reaction: neopinone = codeinone

For diagram of reaction click here

Glossary: neopinone = 3-methoxy-17-methyl-8,14-didehydro-4,5α-epoxymorphinan-6-one
codeinone = 3-methoxy-17-methyl-7,8-didehydro-4,5α-epoxymorphinan-6-one

Other name(s): NISO (gene name)

Systematic name: neopinone Δ87-isomerase

Comments: The enzyme, characterized from the opium poppy (Papaver somniferum), participates in the biosynthesis of morphine. It also catalyses the isomerization of neomorphinone and morphinone.

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


1. Dastmalchi, M., Chen, X., Hagel, J.M., Chang, L., Chen, R., Ramasamy, S., Yeaman, S. and Facchini, P.J. Neopinone isomerase is involved in codeine and morphine biosynthesis in opium poppy. Nat. Chem. Biol. 15 (2019) 384-390. [PMID: 30886433]

[EC created 2022]

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