IUBMB Enzyme Nomenclature


Accepted name: unspecific monooxygenase

Reaction: RH + [reduced NADPH-hemoprotein reductase] + O2 = ROH + [oxidized NADPH-hemoprotein reductase] + H2O

Other name(s): microsomal monooxygenase; xenobiotic monooxygenase; aryl-4-monooxygenase; aryl hydrocarbon hydroxylase; microsomal P-450; flavoprotein-linked monooxygenase; flavoprotein monooxygenase

Systematic name: substrate,reduced-flavoprotein:oxygen oxidoreductase (RH-hydroxylating or -epoxidizing)

Comments: 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: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9038-14-6


1. Booth, J. and Boyland, E. The biochemistry of aromatic amines. 3. Enzymic hydroxylation by rat-liver microsomes. Biochem. J. 66 (1957) 73-78. [PMID: 13426111]

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 (1971) 264-265. [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 (1976) 7929-7939. [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 (1988) 159-170. [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 (1979) 282-289. [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 (1979) 10405-10414. [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 (1981) 12068-12075. [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 (1981) 12058-12075. [PMID: 7298644]

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 (1989) 305-312. [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 (1972) 1727-1734. [PMID: 4401153]

11. Mitoma, C., Posner, H.S., Reitz, H.C. and Udenfriend, S. Enzymic hydroxylation of aromatic compounds. Arch. Biochem. Biophys. 61 (1956) 431-441. [PMID: 13314626]

12. Mitoma, C. and Udenfriend, S. Aryl-4-hydroxylase. Methods Enzymol. 5 (1962) 816-819.

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 (1981) 5865-5871. [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 (1968) 6242-6249. [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)beta. Arch. Biochem. Biophys. 267 (1988) 31-37. [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 (1981) 2168-2175. [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 (1976) 746-758. [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]

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