EC - Unspecific monooxygenase

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IntEnz Enzyme Nomenclature


Accepted name:
unspecific monooxygenase
Other names:
aryl hydrocarbon hydroxylase
flavoprotein monooxygenase
flavoprotein-linked monooxygenase
microsomal P-450
microsomal monooxygenase
xenobiotic monooxygenase
cytochrome P450
microsomal P450
Systematic name:
substrate,reduced-flavoprotein:oxygen oxidoreductase (RH-hydroxylating or -epoxidizing)




A group of P-450 heme-thiolate proteins, acting on a wide range of substrates including many xenobiotics, steroids, fatty acids, vitamins and prostaglandins; reactions catalysed include hydroxylation, epoxidation, N-oxidation, sulfooxidation, N-, S- and O-dealkylations, desulfation, deamination, and reduction of azo, nitro and N-oxide groups. Together with EC, NADPH—hemoprotein reductase, it forms a system in which two reducing equivalents are supplied by NADPH. Some of the reactions attributed to EC, alkane 1-monooxygenase, belong here.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UM-BBD , UniPathway
Protein domains and families: PROSITE:PDOC00081
Structural data: CSA , EC2PDB
Gene Ontology: GO:0070330
CAS Registry Number: 62213-32-5
UniProtKB/Swiss-Prot: (238) [show] [UniProt]


  1. Booth, J. and Boyland, E.
    The biochemistry of aromatic amines. 3. Enzymic hydroxylation by rat-liver microsomes.
    Biochem. J. 66 : 73-78 (1957).
  2. Fujita, T. and Mannering, G.J.
    Differences in soluble P-450 hemoproteins from livers of rats treated with phenobarbital and 3-methylcholanthrene.
    Chem.-Biol. Interact. 3 : 264-265 (1971). [PMID: 5132997]
  3. Haugen, D.A. and Coon, M.J.
    Properties of electrophoretically homogeneous phenobarbital-inducible and β-naphthoflavone-inducible forms of liver microsomal cytochrome P-450.
    J. Biol. Chem. 251 : 7929-7939 (1976). [PMID: 187601]
  4. Imaoka, S., Inoue, K. and Funae, Y.
    Aminopyrine metabolism by multiple forms of cytochrome P-450 from rat liver microsomes: simultaneous quantitation of four aminopyrine metabolites by high-performance liquid chromatography.
    Arch. Biochem. Biophys. 265 : 159-170 (1988). [PMID: 3415241]
  5. Johnson, E.F., Zounes, M. and Müller-Eberhard, U.
    Characterization of three forms of rabbit microsomal cytochrome P-450 by peptide mapping utilizing limited proteolysis in sodium dodecyl sulfate and analysis by gel electrophoresis.
    Arch. Biochem. Biophys. 192 : 282-289 (1979). [PMID: 434823]
  6. Kupfer, D., Miranda, G.K., Navarro, J., Piccolo, D.E. and Theoharides, A.D.
    Effect of inducers and inhibitors of monooxygenase on the hydroxylation of prostaglandins in the guinea pig. Evidence for several monooxygenases catalyzing ω- and ω-1-hydroxylation.
    J. Biol. Chem. 254 : 10405-10414 (1979). [PMID: 489601]
  7. Lang, M.A., Gielen, J.E. and Nebert, D.W.
    Genetic evidence for many unique liver microsomal P-450-mediated monooxygenase activities in heterogeneic stock mice.
    J. Biol. Chem. 256 : 12068-12075 (1981). [PMID: 7298645]
  8. Lang, M.A. and Nebert, D.W.
    Structural gene products of the Ah locus. Evidence for many unique P-450-mediated monooxygenase activities reconstituted from 3-methylcholanthrene-treated C57BL/6N mouse liver microsomes.
    J. Biol. Chem. 256 : 12058-12075 (1981). [PMID: 7298645]
  9. Leo, M.A., Lasker, J.M., Rauby, J.L., Kim, C.I., Black, M. and Lieber, C.S.
    Metabolism of retinol and retinoic acid by human liver cytochrome P450IIC8.
    Arch. Biochem. Biophys. 269 : 305-312 (1989). [PMID: 2916844]
  10. Lu, A.Y.H., Kuntzman, S.W., Jacobson, M. and Conney, A.H.
    Reconstituted liver microsomal enzyme system that hydroxylates drugs, other foreign compounds, and endogenous substrates. II. Role of the cytochrome P-450 and P-448 fractions in drug and steroid hydroxylations.
    J. Biol. Chem. 247 : 1727-1734 (1972). [PMID: 4401153]
  11. Mitoma, C., Posner, H.S., Reitz, H.C. and Udenfriend, S.
    Enzymic hydroxylation of aromatic compounds.
    Arch. Biochem. Biophys. 61 : 431-441 (1956).
  12. Mitoma, C. and Udenfriend, S.
    Methods Enzymol. 5 : 816-819 (1962).
  13. Napoli, J.L., Okita, R.T., Masters, B.S. and Horst, R.L.
    Identification of 25,26-dihydroxyvitamin D3 as a rat renal 25-hydroxyvitamin D3 metabolite.
    Biochemistry 20 : 5865-5871 (1981). [PMID: 7295706]
  14. Nebert, D.W. and Gelboin, H.V.
    Substrate-inducible microsomal aryl hydroxylase in mammalian cell culture. I. Assay and properties of induced enzyme.
    J. Biol. Chem. 243 : 6242-6249 (1968). [PMID: 4387094]
  15. Suhara, K., Ohashi, K., Takahashi, K. and Katagiri, M.
    Aromatase and nonaromatizing 10-demethylase activity of adrenal cortex mitochondrial P-450(11)β
    Arch. Biochem. Biophys. 267 : 31-37 (1988). [PMID: 3264134]
  16. Theoharides, A.D. and Kupfer, D.
    Evidence for different hepatic microsomal monooxygenases catalyzing ω- and (ω-1)-hydroxylations of prostaglandins E1 and E2. Effects of inducers of monooxygenase on the kinetic constants of prostaglandin hydroxylation.
    J. Biol. Chem. 256 : 2168-2175 (1981). [PMID: 7462235]
  17. Thomas, P.E., Lu, A.Y.H., Ryan, D., West, S.B., Kawalek, J. and Levin, W.
    Immunochemical evidence for six forms of rat liver cytochrome P450 obtained using antibodies against purified rat liver cytochromes P450 and P448.
    Mol. Pharmacol. 12 : 746-758 (1976). [PMID: 825720]

[EC created 1961 as EC, transferred 1965 to EC, transferred 1972 to EC (EC created 1972, incorporated 1976, EC created 1972, incorporated 1984), modified 2015]