Leumorphin is a novel endogenous opioid peptide in man.
Porcine leumorphin, a putative opioid peptide corresponding to amino acid residues 228-256 of preproenkephalin B has been demonstrated to exist in the porcine neurointermediate pituitary. A recent study on the sequence analysis of genomic DNA of human preproenkephalin B has shown that human leumorphin differs in 3 amino acid residues from porcine leumorphin. In order to clarify whether leumorphin is an endogenous opioid peptide in man, we have studied its existence in the human brain using a radioimmunoassay and its opioid activity by a bioassay with the guinea-pig ileum myenteric plexus-longitudinal muscle preparation. High performance gel permeation chromatography and reverse-phase high performance liquid chromatography coupled with the radioimmunoassay for leumorphin have revealed that human leumorphin exists in water extracts of the human striatum. In the guinea-pig ileum assay, synthetic human leumorphin exhibited potent opioid activity, with the concentration of 3nM to give 50 per cent inhibition. These results indicate that leumorphin is a novel endogenous opioid peptide in man.
D000328:Adult; D000818:Animals; D001923:Brain Chemistry; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004745:Enkephalins / Q000032:analysis* / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D007082:Ileum / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D011498:Protein Precursors / Q000032:analysis* / Q000494:pharmacology; D011863:Radioimmunoassay / Q000379:methods
D004745:Enkephalins; D011498:Protein Precursors; C033660:preproenkephalin