Resolution of the methane mono-oxygenase of Methylococcus capsulatus (Bath) into three components. Purification and properties of component C, a flavoprotein

Biochem J. 1978 May 1;171(2):461-8. doi: 10.1042/bj1710461.


1. Ion-exchange chromatography resolves the methane mono-oxygenase from soluble extracts of Methylococcus capsulatus (Bath) into three fractions. 2. Fractions A and B are comparatively stable at 0 degrees C, whereas fraction C is very unstable unless kept in the presence of sodium thioglycollate (1-10 mM) or dithiothreitol (5-10mM). 3. The active component from fraction C was purified some 80-fold. 4. Purified component C has mol. wt. 42000. Its solutions are yellow with absorption maxima at 270 and 465 nm and a shoulder at 395 nm. The 465 nm peak is abolished by reduction with NADH or sodium dithionite, or by photoreduction in the presence of EDTA. A new spectral species, probably a neutral flavin semiquinone, is observed on partial reduction of component C. 5. No copper was detected in samples of purified component C, but the protein contains 1.3-1.5 atoms of iron/molecule. 6. On boiling, component C releases a yellow-green fluorescent material that has been identified as FAD from its absorption and fluorescence spectra and by t.l.c. 7. Component C contains 1 mol of FAD/mol of protein.

MeSH terms

  • Copper / analysis
  • Flavoproteins / analysis
  • Flavoproteins / isolation & purification*
  • Iron / analysis
  • Macromolecular Substances
  • Methane
  • Methylococcaceae
  • Molecular Weight
  • Oxidation-Reduction
  • Oxygenases / analysis*
  • Spectrophotometry


  • Flavoproteins
  • Macromolecular Substances
  • Copper
  • Iron
  • Oxygenases
  • Methane