Inhibition of peptide amidation by disulfiram and diethyldithiocarbamate.
Peptidylglycine alpha-amidating monooxygenase is a copper- and ascorbate-dependent enzyme that converts peptides with COOH-terminal glycine residues into the corresponding alpha-amidated product peptides. The relatively selective copper chelator N,N-diethyldithiocarbamate (DDC) and its disulfide dimer, disulfiram (Antabuse), were used to determine whether the availability of copper affects the production of two alpha-amidated pro-ACTH/endorphin-derived peptides, alpha-melanotropin (alpha MSH) and joining peptide. When mouse pituitary corticotropic tumor cells (AtT-20) were grown in medium containing micromolar concentrations of disulfiram or DDC, alpha-amidation of newly synthesized joining peptide was specifically inhibited in a dose-dependent manner. In rats injected twice with disulfiram or DDC, the ability of the intermediate pituitary to alpha-amidate newly synthesized alpha MSH and joining peptide was inhibited in a dose-dependent manner; at disulfiram doses equivalent to those used in alcohol abuse therapy (4 mg/kg/day), only about 10% of the newly synthesized peptides were correctly alpha-amidated. Chronic treatment of rats with DDC or disulfiram produced a dose-dependent increase in the pituitary content of glycine-extended alpha MSH and joining peptide; the total amount of pro-ACTH/endorphin-related material was unaltered. After 11 days of treatment with 4 mg/kg/day disulfiram, about one-third of the pituitary alpha MSH and joining peptide were present in the glycine-extended rather than the alpha-amidated form; pituitary extracts normally contain almost entirely alpha-amidated peptides.
D000818:Animals; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000494:pharmacology; D004221:Disulfiram / Q000494:pharmacology*; D004050:Ditiocarb / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000378:metabolism; D051379:Mice; D006899:Mixed Function Oxygenases; D009097:Multienzyme Complexes; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000378:metabolism*; D010902:Pituitary Gland / Q000201:enzymology; D010911:Pituitary Neoplasms / Q000201:enzymology; D051381:Rats; D013859:Thiocarbamates / Q000494:pharmacology*
D009097:Multienzyme Complexes; D013859:Thiocarbamates; D003300:Copper; D009074:Melanocyte-Stimulating Hormones; D004050:Ditiocarb; D006899:Mixed Function Oxygenases; C035189:peptidylglycine monooxygenase; D000587:Oxidoreductases Acting on CH-NH Group Donors; D004221:Disulfiram