IUBMB Enzyme Nomenclature


Accepted name: 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione monooxygenase

Reaction: 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione + FMNH2 + O2 = 3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione + FMN + H2O

Other name(s): HsaA

Systematic name: 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione,FMNH2:oxygen oxidoreductase

Comments: This bacterial enzyme participates in the degradation of several steroids, including cholesterol and testosterone. It can use either FADH or FMNH2 as flavin cofactor. The enzyme forms a two-component system with a reductase (HsaB) that utilizes NADH to reduce the flavin, which is then transferred to the oxygenase subunit.

Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, Metacyc, PDB, CAS registry number:


1. Dresen, C., Lin, L.Y., D'Angelo, I., Tocheva, E.I., Strynadka, N. and Eltis, L.D. A flavin-dependent monooxygenase from Mycobacterium tuberculosis involved in cholesterol catabolism. J. Biol. Chem. 285 (2010) 22264-22275. [PMID: 20448045]

[EC created 2011]

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