title: Isolation, sequencing, synthesis, and pharmacological characterization of two brain neuropeptides that modulate the action of morphine.
abstract: Two peptides that crossreact with an antiserum raised against Phe-Met-Arg-Phe-NH2 were purified from bovine brain extract. Their structures were determined to be Ala-Gly-Glu-Gly-Leu-Ser-Ser-Pro-Phe-Trp-Ser-Leu-Ala-Ala-Pro-Gln-Arg-Phe- NH2 and Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2. The sequences were determined by gas-phase sequencing, except for the COOH-terminal phenylalaninamides. These were assigned on the basis of the reactivity of the peptides with the anti-Phe-Met-Arg-Phe-NH2 antiserum, which appears to recognize the determinant -Arg-Phe-NH2. Both peptides were synthesized, and the synthetic peptides were found to have the same HPLC retention times as the endogenous Phe-Met-Arg-Phe-NH2-immunoreactive peptides, thus confirming the assignment of phenylalaninamide to the COOH-terminal positions. Both of the synthetic peptides were found to decrease tail-flick latency in rats, and the octapeptide was more active than the octadecapeptide. The octapeptide was found also to attenuate the prolongation of the tail-flick latency induced by morphine.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D009020:Morphine / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000302:isolation & purification* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009419:Nerve Tissue Proteins; D009020:Morphine