Overexpression and purification of the particulate methane monooxygenase from Methylococcus capsulatus (Bath)

The particulate methane monooxygenase (pMMO) is a multi-copper enzyme that mediates the facile conversion of methane to methanol in methanotrophic bacteria. As a membrane-bound multi-subunit metalloprotein, the highly active protein has been difficult to isolate and purify to homogeneity for biochemical and biophysical studies. In this chapter, we describe a method to overexpress pMMO with good specific activity in high yields in the intracytoplasmic membranes of the host organism, together with two protocols to isolate and purify the enzyme from pMMO-enriched membranes without loss of the copper cofactors and enzymatic activity.