Synthesis of alpha- and beta-melanocyte stimulating hormones.

The solid phase synthesis of alpha-melanocyte stimulating hormone (alpha-MSH) using the benzhydrylamine resin and a number of recently described side chain protecting groups is given. The carboxamide terminal peptide was obtained directly by treatment of the peptide resin with liquid hydrogen fluoride at 0 degrees in the presence of carbonium ion scavengers. The solid phase synthesis of the C-terminal carboxylate hormone, porcine beta-melanocyte stimulating hormone (beta p-MSH), using a 1% cross-linked Merrifield resin and the same side chain protecting groups as in the alpha-MSH synthesis also is presented. Purification of both peptides was carried out by conventional chromatographic techniques. Both hormones were fully active and beta p-MSH was slightly more potent than previously reported in the literature.