Synthesis of the nonacosapeptide corresponding to mammalian glucagon.

Abstract

The nonacosapeptide corresponding to the entire amino acid sequence of mammalian glucagon was synthesized via the corresponding sulfoxide, [Met (O)27]-glucagon. For synthesis of the protected nonacosapeptide six subunits were prepared to serve for building blocks. The condensations of subunits were achieved by the HONB-DCC method. Finally, all the protecting groups of the protected peptide were removed by the treatment with methanesulfonic acid-anisole to give [Met (O)27]-glucagon. The sulfoxide was then treated with 3% aqueous thioglycolic acid to give mammalian glucagon. The product was successfully crystallized from dilute aqueous sodium chloride solution. The N to O acyl migration of serine and threonine residues with methanesulfonic acid treatment was studied in detail.