Catalyzes the O-methylation, and thereby the inactivation, of catecholamine neurotransmitters and catechol hormones. Also shortens the biological half-lives of certain neuroactive drugs, like L-DOPA, alpha-methyl DOPA and isoproterenol. a catechol + S-adenosyl-L-methionine = a guaiacol + H(+) + S-adenosyl-L-homocysteine 2-hydroxyestrone + S-adenosyl-L-methionine = 2-hydroxy-3-methoxy-estrone + H(+) + S-adenosyl-L-homocysteine 4-hydroxyestrone + S-adenosyl-L-methionine = 4-methoxyestrone + H(+) + S-adenosyl-L-homocysteine 2-hydroxyestrone + S-adenosyl-L-methionine = 2-methoxyestrone + H(+) + S-adenosyl-L-homocysteine 4-hydroxy-17beta-estradiol + S-adenosyl-L-methionine = 4-methoxy-17beta-estradiol + H(+) + S-adenosyl-L-homocysteine 2-hydroxy-17beta-estradiol + S-adenosyl-L-methionine = 2-hydroxy-3-methoxy-17beta-estradiol + H(+) + S-adenosyl-L-homocysteine 2-hydroxy-17beta-estradiol + S-adenosyl-L-methionine = 2-methoxy-17beta-estradiol + H(+) + S-adenosyl-L-homocysteine Binds 1 Mg(2+) ion per subunit. The N-terminus is blocked. Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-dependent O-methyltransferase family. Truncated N-terminus. Truncated N-terminus.