Proenkephalin-A-derived peptides are present in human brain.
The opioid peptides [Met] enkephalin-Arg6-Phe7, [Met]-enkephalin-Arg6-Gly7-Leu8, and BAM-12P were identified in various ares of human brain by use of a combination of radioimmunoassay (RIA), gel filtration, and high performance liquid chromatography (HPLC). The highest levels of each peptide were found in striatum, followed by substantia nigra, hypothalamus, and medulla. In all areas, the relative concentrations were [Met] enkephalin-Arg6-Phe7 less than [Met] enkephalin-Arg6-Gly7-Leu8 less than BAM-12P. The apparent existence of BAM-12P suggests that the enzymatic processing of the proenkephalin A precursor in human brain is not restricted to cleavage at sites with two basic amino acids. Our results provide evidence that a precursor similar or identical to that present in the adrenal medulla exists in human brain. It appears that the processing mechanisms are different, as virtually none of the immunoreactivity found in the brain was comprised of the higher molecular weight forms of the peptides seen in the adrenal.
D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000032:analysis; D006801:Humans; D011498:Protein Precursors / Q000032:analysis*; D011863:Radioimmunoassay; D014018:Tissue Distribution
D011498:Protein Precursors; D004744:Enkephalin, Methionine; C027511:enkephalin-Met, Arg(6)-Phe(7)-; C026771:BAM 12P; C033453:enkephalin-Met, Arg(6)-Gly(7)-Leu(8)-