Synthesis and biological activity of camel and bovine beta-melanotropins

Two natural occurring melanotropins, camel betaC2-MSH and bovine beta-MSH, have been synthesized by improved solid-phase procedures. The coupling reaction of tert-butyloxycarbonylamino acids was achieved by using their preformed symmetrical anhydrides. The synthetic hormones were purified by gel filtration on Sephadex G-10 and G-25, chromatography on carboxymehtylcellulose, and partition chromatography on Sephadex G-25 with final yields of 56 and 35% for betac2-MSH and betab-MSH, respectively. They were then shown to be identical with their natural hormones in amino acid analysis, paper electrophoresis, disc electrophoresis, thin-layer chromatography, enzymic digests, and bioassays. Bioassay data of these two synthetic melanotropins indicate that the replacement of Ser by Gly in betab-MSH does not change its melanocyte-stimulating activity.