Enzymatic inactivation of peptide hormones possessing a C-terminal amide group.
A partially purified enzyme extracted from the bladder of the toad, Bufo marinus L., was found to cleave the glycine amide moiety from oxytocin, 8-lysine-vasopressin, 8-arginine-vasopressin, and other hormone analogs terminating in a primary carboxamide group; however, this enzyme does not attack hormone analogs terminating with a methylamide, dimethylamide, or carboxyl group. Preliminary experiments indicate that a functionally similar enzyme is also present in the mammalian kidney, the major target organ of neurohypophyseal antidiuretic hormones. This enzyme, besides inactivating oxytocin and 8-lysine-vasopressin, also cleaves the phenylalanine amide moiety from a tetrapeptide analog of gastrin, another hormone terminating in a primary carboxamide group. Attention is drawn to the possible general significance of "carboxamidopeptidases" for the termination of the action of peptide hormones in which the C-terminal amino acid residue bears a carboxamide group.
D000577:Amides / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001001:Anura; D004789:Enzyme Activation; D010121:Oxytocin / Q000378:metabolism*; D001743:Urinary Bladder / Q000201:enzymology*; D014667:Vasopressins / Q000378:metabolism*
D000577:Amides; D014667:Vasopressins; D010121:Oxytocin