IUBMB Enzyme Nomenclature


Accepted name: cyclopenase

Reaction: (–)-cyclopenine = viridicatin + methyl isocyanate

For reaction pathway click here and mechanism click here.

Glossary: (–)-cyclopenine = (3S,3'R)-4-methyl-3'-phenyl-1H-spiro[1,4-benzodiazepine-3,2'-oxirane]-2,5-dione
viridicatin = 3-hydroxy-4-phenyl-1H-quinolin-2-one

Other name(s): asqI (gene name)

Systematic name: (–)-cyclopenine methyl-isocyanate lyase (viridicatin-forming)

Comments: This fungal enzyme catalyses a key reaction in the biosynthesis of quinolone compounds, converting the benzodiazepine structure into a quinolone structure. The enzyme is also active with (–)-4'-methoxycyclopenine.

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


1. Kishimoto, S., Hara, K., Hashimoto, H., Hirayama, Y., Champagne, P.A., Houk, K.N., Tang, Y. and Watanabe, K. Enzymatic one-step ring contraction for quinolone biosynthesis. Nat. Commun. 9 (2018) 2826. [PMID: 30026518]

[EC created 2022]

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