IUBMB Enzyme Nomenclature


Accepted name: menaquinone-9 β-reductase

Reaction: menaquinone-9 + reduced acceptor = β-dihydromenaquinone-9 + acceptor

For diagram of reaction click here.

Glossary: β-dihydromenaquinone-9 = MK-9(II-H2) = 2-methyl-3-[(2E,10E,14E,18E,22E,26E,30E,33E)-3,7,11,15,19,23,27,31,35-nonamethylhexatriaconta-2,10,14,18,22,26,30,33-octaen-1-yl]naphthalene-1,4-dione

Other name(s): MenJ

Systematic name: menaquinone-9 oxidoreductase (β-dihydromenaquinone-9-forming)

Comments: The enzyme from the bacterium Mycobacterium tuberculosis reduces the β-isoprene unit of menaquinone-9, forming the predominant form of menaquinone found in mycobacteria. Contains FAD.

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


1. Upadhyay, A., Fontes, F.L., Gonzalez-Juarrero, M., McNeil, M.R., Crans, D.C., Jackson, M. and Crick, D.C. Partial saturation of menaquinone in Mycobacterium tuberculosis: function and essentiality of a novel reductase, MenJ. ACS Cent. Sci. 1 (2015) 292-302. [PMID: 26436137]

[EC created 2017]

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