title: Two adrenal opioid polypeptides: proposed intermediates in the processing of proenkephalin.
abstract: Two enkephalin-containing polypeptides of 3600 and 4900 daltons have been isolated from extracts of bovine adrenal medulla, purified to homogeneity, and analyzed by a combination of automated Edman degradation and enzymatic time course hydrolysis. The 4900-dalton polypeptide contains two copies of enkephalin, one an internal [Met]enkephalin sequence, the other a [Leu]enkephalin sequence at the carboxyl terminus. Sequence analysis of the 3600-dalton polypeptide has not been completed, but the polypeptide has been shown to contain a single [Met]enkephalin sequence followed by an -Arg-Phe linkage that forms the carboxyl terminus of the molecule. On the basis of these and other findings, we propose that the above enkephalin-containing polypeptides are intermediates in the biosynthesis of the enkephalins and that they are generated by posttranslational processing from a large multivalent enkephalin precursor molecule, proenkephalin. The term "multivalent" is used to indicate a polypeptide with many identical functional sequences.
mesh_terms: D000313:Adrenal Medulla / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002837:Chromaffin Granules / Q000378:metabolism*; D002838:Chromaffin System / Q000378:metabolism*; D004723:Endorphins / Q000096:biosynthesis*; D004745:Enkephalins / Q000096:biosynthesis* / Q000302:isolation & purification; D010446:Peptide Fragments / Q000032:analysis; D011498:Protein Precursors / Q000096:biosynthesis* / Q000302:isolation & purification; D014357:Trypsin
chemical_list: D004723:Endorphins; D004745:Enkephalins; D010446:Peptide Fragments; D011498:Protein Precursors; C029992:proenkephalin; D014357:Trypsin