title: Resolution of the methane mono-oxygenase of Methylococcus capsulatus (Bath) into three components. Purification and properties of component C, a flavoprotein.
abstract: 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: D003300:Copper / Q000032:analysis; D005420:Flavoproteins / Q000032:analysis / Q000302:isolation & purification*; D007501:Iron / Q000032:analysis; D046911:Macromolecular Substances; D008697:Methane; D008772:Methylococcaceae; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000032:analysis*; D013053:Spectrophotometry
chemical_list: D005420:Flavoproteins; D046911:Macromolecular Substances; D003300:Copper; D007501:Iron; D010105:Oxygenases; D008697:Methane