title: Synthesis of protected secretin 16-27 on a Merrifield resin. Examination of ammonolysis conditions for preparing carboxamide terminal protected peptides suitable for fragment condensation.
abstract: The partially protected dodecapeptide to secretin, H-Ser(Bzl)-Ala-Arg(Tos)-Leu-Gln-Arg(Tos)-Leu-Leu-Gln-Gly-Leu-Val-NH2 (protected secretin 16-27) was prepared using a standard Merrifield resin and solid phase synthesis methods. For comparative purposes the unprotected peptide also was prepared on a benz-hydrylamine resin. Contrary to previous reports, the valine C-terminal peptide can be cleaved from the resin and the amide obtained in high yield. A variety of conditions were examined to accomplish the cleavage of the peptide from the resin in its carboxamide terminal form. The best conditions found were trans-esterification followed by ammonolysis in a mixed solvent system. A thin-layer chromatography system which clearly separates the methyl ester and carboxamide terminal secretin 16-27 was developed.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001559:Benzhydryl Compounds; D002855:Chromatography, Thin Layer; D004951:Esterification; D010446:Peptide Fragments; D012116:Resins, Plant; D012633:Secretin / Q000031:analogs & derivatives* / Q000032:analysis / Q000138:chemical synthesis
chemical_list: D000596:Amino Acids; D001559:Benzhydryl Compounds; D010446:Peptide Fragments; D012116:Resins, Plant; D012633:Secretin