COMT (Catechol-O-methyltransferase) is an enzyme involved in the metabolism of catecholamine neurotransmitters such as dopamine, norepinephrine, and epinephrine. It catalyzes the transfer of a methyl group from S-adenosylmethionine to the hydroxyl group of the substrate, participating in the process of inactivation. COMT exists in two forms: soluble COMT (S-COMT) and membrane-bound COMT (MB-COMT), expressed in various tissues including the liver, kidneys, and brain. Variations in the COMT gene, such as the Val158Met polymorphism, affect enzyme activity and the rate of neurotransmitter metabolism, contributing to differences in susceptibility to psychiatric disorders, pain sensitivity, and cognitive function.