Characteristic properties and kinetic analysis with neurotoxins of porcine FAD-containing monooxygenase

Ru Feng Wu, Yoshiyuki Ichikawa

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


An FAD-containing monooxygenase (EC was purified from porcine liver microsomes by a new purification procedure and confirmed to give an electrophoretically single protein band. The optical and CD spectra, fluorescence and molar extinction coefficients of the FMO were investigated. The activity of the FMO was examined kinetically with neurotoxins, 1-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP), 1,2,3,4-tetrahydroisoquinoline (TIQ), and 1-methyl-6,7-dihydroxytetrahydroisoquinoline (MDTIQ), as substrates. The kinetic parameters of the FMO for the neurotoxins, molecular oxygen and electron donors were determined, in comparison, on with those of dimethylaniline. The CD spectrum of the FMO was measured in the absence and presence of NADP+, dimethylaniline or both. The results showed that the FMO metabolized the neurotoxins, and that NADH was a weak electron donor for it. The CD spectrum of the FMO in the oxidized form, which acts as an oxidase and oxygenase, unlike that of d-amino-acid oxidase, showed negative ellipticity, the secondary structure of the FMO changed, and the α-helix structure of the monooxygenase was affected by the formation of a complex of the FMO with NADP+, DMA or both.

Original languageEnglish (US)
Pages (from-to)204-210
Number of pages7
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Issue number2
StatePublished - Oct 19 1994


  • FAD-containing monooxygenase
  • Flavoenzyme
  • Kinetics
  • Neurotoxin
  • Oxygenase

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology


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