Copper Containing Hydroxylases

Dopamine ^-hydroxylase (EC 1.14.17.1) is a copper-containing enzyme involved in the synthesis of the catecholamines noradrenaline and adrenaline from tyr-osine in the adrenal medulla and central nervous system. The active enzyme contains Cu+, which is oxidized to Cu2+ during the hydroxylation of the substrate; reduction back to Cu+ specifically requires ascorbate, which is oxidized to monodehydroascorbate.

A number of peptide hormones have a terminal amide, and amidation is essential for biological activity. The amide group is derived from a glycine residue in the precursor peptide, by proteolysis to leave a carboxy terminal glycine. This is hydroxy-lated on the a-carbon; the hydroxyglycine decomposes nonenzymically to yield the amidated peptide and glyoxylate. This reaction is catalyzed by pepti-dyl glycine hydroxylase (peptidyl a-amidase, EC 1.14.17.3); like dopamine ^-hydroxylase, it is a copper-containing enzyme, and it requires ascorbate as the electron donor.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

Get My Free Ebook


Post a comment