Unspecific monooxygenase

In enzymology, an unspecific monooxygenase is an enzyme that catalyzes the chemical reaction

RH + reduced flavoprotein + O2 rightleftharpoons ROH + oxidized flavoprotein + H2O

The 3 substrates of this enzyme are RH, reduced flavoprotein, and O2, whereas its 3 products are ROH, oxidized flavoprotein, and H2O.

This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen into the other donor. The systematic name of this enzyme class is substrate,reduced-flavoprotein:oxygen oxidoreductase (RH-hydroxylating or -epoxidizing). Other names in common use include microsomal monooxygenase, xenobiotic monooxygenase, aryl-4-monooxygenase, aryl hydrocarbon hydroxylase, microsomal P-450, flavoprotein-linked monooxygenase, and flavoprotein monooxygenase. This enzyme participates in 7 metabolic pathways: fatty acid metabolism, androgen and estrogen metabolism, gamma-hexachlorocyclohexane degradation, tryptophan metabolism, arachidonic acid metabolism, linoleic acid metabolism, and metabolism of xenobiotics by cytochrome p450. It employs one cofactor, heme.

Structural studies

As of late 2007, 53 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and .


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  • Imaoka S, Inoue K, 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. 265 159–70.
  • Johnson EF, Zounes MC, Muller-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. 192 282–9.
  • Kupfer D, Miranda GK, Navarro J, Piccolo DE, Theoharides AD "Effect of inducers and inhibitors of monooxygenase on the hydroxylation of prostaglandins in the guinea pig. Evidence for several monooxygenases catalyzing omega- and omega-1-hydroxylation". J. Biol. Chem. 254 10405–14.
  • Lang MA, Gielen JE, Nebert DW "Genetic evidence for many unique liver microsomal P-450-mediated monooxygenase activities in heterogeneic stock mice". J. Biol. Chem. 256 12068–75.
  • Lang MA, Nebert DW "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 12058–67.
  • Leo MA, Lasker JM, Raucy JL, Kim CI, Black M, Lieber CS "Metabolism of retinol and retinoic acid by human liver cytochrome P450IIC8". Arch. Biochem. Biophys. 269 305–12.
  • Lu AY, Kuntzman R, West S, Jacobson M, Conney AH "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 1727–34.
  • MITOMA C, POSNER HS, REITZ HC, UDENFRIEND S "Enzymatic hydroxylation of aromatic compounds". Arch. Biochem. Biophys. 61 431–41.
  • Mitoma C and Udenfriend S "Aryl-4-hydroxylase". Methods Enzymol. 5 816–819.
  • Napoli JL, Okita RT, Masters BS, Horst RL "Identification of 25,26-dihydroxyvitamin D3 as a rat renal 25-hydroxyvitamin D3 metabolite". Biochemistry. 20 5865–71.
  • Nebert DW, Gelboin HV "Substrate-inducible microsomal aryl hydroxylase in mammalian cell culture. I. Assay and properties of induced enzyme". J. Biol. Chem. 243 6242–9.
  • Suhara K, Ohashi K, Takahashi K, Katagiri M "Aromatase and nonaromatizing 10-demethylase activity of adrenal cortex mitochondrial P-450(11)beta". Arch. Biochem. Biophys. 267 31–7.
  • Theoharides AD, Kupfer D "Evidence for different hepatic microsomal monooxygenases catalyzing omega- and (omega-1)-hydroxylations of prostaglandins E1 and E2 Effects of inducers of monooxygenase on the kinetic constants of prostaglandin hydroxylation". J. Biol. Chem. 256 2168–75.
  • Thomas PE, Lu AY, Ryan D, West SB, Kawalek J, 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. 12 746–58.

External links

The CAS registry number for this enzyme class is .

Gene Ontology (GO) codes

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