Monoamine oxidase (MAO) breaks down noradrenaline and adrenaline through oxidation, while catechol-O-methyltransferase (COMT) uses methylation to deactivate these catecholamines.
The enzymes that break down noradrenaline and adrenaline are monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). MAO exerts its effect through the oxidation of monoamines, removing hydrogen from the substrate to catalyze their breakdown.
This process often occurs within the mitochondria of various tissues, including the brain and liver. On the other hand, COMT uses S-adenosylmethionine (SAM) as a methyl donor to methylate catecholamines like noradrenaline and adrenaline, effectively decreasing their activity. This takes place in the cytosol of cells.