Methylotrophs use the electron transport chain to conserve energy produced from the oxidation of <chem>C1</chem> compounds. An additional activation step is required in methanotrophic metabolism to allow degradation of chemically-stable methane. This oxidation to methanol is catalyzed by MMO, which incorporates one oxygen atom from <chem>O2</chem> into methane and reduces the other oxygen atom to water, requiring two equivalents of reducing power. Methanol is then oxidized to formaldehyde through the action of methanol dehydrogenase (MDH) in bacteria, or a non-specific alcohol oxidase in yeast. Electrons from methanol oxidation are passed to a membrane-associated quinone of the electron transport chain to produce <chem>ATP</chem>.