The particulate methane monooxygenase from Methylococcus capsulatus (Bath) is a novel copper-containing three-subunit enzyme – Isolation and characterization

The particulate methane monooxygenase (pMMO) is known to be very difficult to study mainly due to its unusual activity instability in vitro. By cultivating Methylococcus capsulatus (Bath) under methane stress conditions and high copper levels in the growth me-dium, membranes highly enriched in the pMMO with exceptionally stable activity can be isolated from these cells. Purified and active pMMO can be subsequently obtained from these membrane preparations using pro-tocols in which an excess of reductants and anaerobic conditions were maintained during membrane solubili-zation by dodecyl b-D-maltoside and purification by chromatography. The pMMO was found to be the major constituent in these membranes, constituting 60–80 % of total membrane proteins. The dominant species of th