Synthesis of Salmon Endorphin

First synthesis of a nonacosapeptide corresponding to the entire amino acid sequence of salmon endorphin, Ac-Tyr-Gly-Gly-Phe-Met-Lys-Pro-Tyr-Thr-Lys-Gln-Ser-His-Lys-Pro-Leu-Ile-Thr-Leu-Leu-Lys-His-Ile-Thr-Leu-Lys-Asn-Glu-Gln-OH, and its des-acetyl derivative was described. Toward the synthesis of this hormone, five fragments, 1-7, 8-15, 16-18, 19-24 and 25-29, were prepared and the fragments were served as the building blocks for the final construction of the entire amino acid sequence of the hormone. The final deprotection of the fully protected peptide was achieved by treatment with trifluoroacetic acid and the purification of the synthetic peptides was effected by a column chromatography on CM-cellulose and then Sephadex LH-20. The synthetic acetylated nonacosapeptide was compared with purified natural salmon endorphin by means of chromatography, electrophoresis and also enzymatic digestion and found to be indistinguishable from natural isolated salmon endorphin. The opiate activity of the synthetic salmon endorphin and des-acetyl salmon endorphin was also described.