Reaction: (+)-cis-isopulegone + NADP+ = (–)-isopiperitenone + NADPH + H+
For diagram of reaction click here.
Systematic name: (+)-cis-isopulegone:NADP+ oxidoreductase
Comments: The reaction occurs in the opposite direction to that shown above. The enzyme participates in the menthol-biosynthesis pathway of Mentha plants. (+)-Pulegone, (+)-cis-isopulegone and (–)-menthone are not substrates. The enzyme has a preference for NADPH as the reductant, with NADH being a poor substitute [2]. The enzyme is highly regioselective for the reduction of the endocyclic 1,2-double bond, and is stereoselective, producing only the 1R-configured product. It is a member of the short-chain dehydrogenase/reductase superfamily.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:
References:
1. Croteau, R. and Venkatachalam, K.V. Metabolism of monoterpenes: demonstration that (+)-cis-isopulegone, not piperitenone, is the key intermediate in the conversion of (–)-isopiperitenone to (+)-pulegone in peppermint (Mentha piperita). Arch. Biochem. Biophys. 249 (1986) 306-315. [PMID: 3755881]
2. Ringer, K.L., McConkey, M.E., Davis, E.M., Rushing, G.W. and Croteau, R. Monoterpene double-bond reductases of the (–)-menthol biosynthetic pathway: isolation and characterization of cDNAs encoding (–)-isopiperitenone reductase and (+)-pulegone reductase of peppermint. Arch. Biochem. Biophys. 418 (2003) 80-92. [PMID: 13679086]