Studies on the Mechanism of Stimulation of Microsomal H2O2 Formation and Benzo(a)pyrene Hydroxylaton by Substrates and Flavone

  • A. G. Hildebrandt
  • C. Bergs
  • G. Heinemeyer
  • E. Schlede
  • I. Roots
  • B. Abbas-Ali
  • A. Schmoldt
Part of the Advances in Experimental Medicine and Biology book series (AEMB)


The addition of activators like flavone and hexobarbital to hepatic microsomes markedly stimulates H2O2 formation. The similar increase observed with flavone of microsomal hydroxylation of benzo(a)pyrene and its inhibition by catalase and methanol suggests but does not prove a necessary interaction of microsomal H2O2 production with benzo(a)pyrene hydroxylation.

Hexobarbital and flavone-stimulated H2O2 formation is optimal at a stoichiometric relationship of these activators and NADPH. This implies either their direct participation as electron donors or their indirect involvement in electron transport by facilitation of stoichiometric substrate cytochrome P-450/NADPH flavoprotein interactions. Steady state kinetic data are consistent with a scheme in which the formation in microsomes of a complex of 1 mole of NADPH with NADPH-cytochrome P-450 reductase and 1 mole hexobarbital with cytochrome P-450 regulates H2O2 formation.


Liver Microsome H202 Production Hepatic Microsome Redox Protein Mixed Function Oxidase 
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Copyright information

© Springer Science+Business Media New York 1982

Authors and Affiliations

  • A. G. Hildebrandt
    • 1
  • C. Bergs
    • 1
  • G. Heinemeyer
    • 1
  • E. Schlede
    • 1
  • I. Roots
    • 1
  • B. Abbas-Ali
    • 2
  • A. Schmoldt
    • 3
  1. 1.Institut für Klinische Pharmakologie der Freien, Klinikum SteglitzUniversität BerlinBerlin 45Germany
  2. 2.College of Medicine Al Mustansiryia UniversityBaghdadIraq
  3. 3.Pharmakologisches InstitutUniversität HamburgGermany

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