. "ACTIVATION"^^ . . "Catechol O-methyltransferase catalyzes the transfer of the methyl group from S-adenosyl-L-methionine to one of the hydroxyl groups of a catechol, in the presence of Mg²⁺. Its physiological function is to inactivate biologically active, or toxic catechols. The membrane-bound isoform has lower K_m values for catechol substrates than the soluble form. The K_m for dopamine was approximately 100-fold lower for the membrane-bound form than the soluble form. The ratio of the products 3-methoxytyramine to 4-methoxytyramine was 8.8. The enzyme showed both substrate and product inhibition. Triton X-100 inhibited the membrane-bound, but not the soluble form of the enzyme. |CITS: [7082642] [6693904] [1847521] [7703232]|."^^ . . . . . "catechol O-methyltransferase"^^ . "catechol O-methyltransferase"^^ . . . . "catechol O-methyltransferase"^^ .