Isolation and structure of a novel C-terminally amidated opioid peptide, amidorphin, from bovine adrenal medulla
Abstract
Biologically active peptide hormones and neurotransmitters have been shown to be enzymatically liberated from larger, inactive precursor molecules by tissue-specific post-translational processing, particularly at the typical cleavage signals of paired basic residues1,2. Subsequent N-terminal or C-terminal modifications may be of importance in regulating the biological activities of these peptides (for review see ref. 3). C-terminal α-amidation is considered to be essential for the biological function of several non opioid peptides4,5. Here we present the isolation and structure of a novel C-terminally amidated opioid peptide, amidorphin, from bovine adrenal medulla. Amidorphin and the recently isolated octapeptide metorphamide6 (adrenorphin7) are the only endogenous opioid peptides in mammals known to possess a C-terminal amide group. The amino acid sequence of amidorphin corresponds to the sequence 104-129 of bovine proenkephalin A (refs 8, 9). Very high concentrations of amidorphin were detected in bovine adrenal medulla and in a further endocrinological system, the hypothalamic-neurohypophyseal axis. Amidorphin may there fore be considered to be a major gene product of the opioid peptide precursor proenkephalin A in these endocrine tissues.
- Publication:
-
Nature
- Pub Date:
- January 1985
- DOI:
- 10.1038/313057a0
- Bibcode:
- 1985Natur.313...57S