An optimized solid phase synthesis strategy- including on-resin lactamization-of astressin, its retro-, inverso-, and retro-inverso isomers as corticotropin releasing factor antagonists

• Published in: Biopolymers 2002-02, Vol.63 (2), p.141-149
• Main Authors: Rijkers, Dirk T. S., den Hartog, Jack A. J., Liskamp, Rob M. J.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; antagonists; beta-Galactosidase - genetics; beta-Galactosidase - metabolism; Cells, Cultured; Circular Dichroism; Corticotropin-Releasing Hormone - antagonists & inhibitors; Corticotropin-Releasing Hormone - chemical synthesis; Corticotropin-Releasing Hormone - chemistry; Corticotropin-Releasing Hormone - metabolism; Corticotropin-Releasing Hormone - pharmacology; cyclic peptides; Genes, Reporter; Glutamic Acid - chemistry; Humans; Lactams - chemistry; Lysine - chemistry; Mice; mimetics; Molecular Sequence Data; Peptide Fragments - chemical synthesis; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Peptide Fragments - pharmacology; peptide synthesis; Peptides - chemical synthesis; Protein Conformation; Protein Structure, Secondary; Receptors, Corticotropin-Releasing Hormone - metabolism; Resins, Plant - chemistry; retro-inverso peptides; Stereoisomerism; Water - chemistry
• ISSN: 0006-3525; 1097-0282
• DOI: 10.1002/bip.10052

This report describes an optimized solid phase synthesis strategy for astressin and new derivatives thereof. The synthesis is based on 9‐fluorenylmethyloxycarbonyl/allyl/tert‐butyl chemistry. The glutamic acid and lysine residue, which together form the cyclic constraint by coupling of their side chains, were protected by allyl functionalities during the synthesis of the linear peptide. Allyl removal by Pd(0) and the construction of the lactam bridge have been performed on‐resin after completion of the chain assembly. This synthetic methodology resulted in high chemical yields (58–72%) and excellent purities of the crude peptides. The peptides were tested for their binding at the corticotropin releasing factor receptor, type 1, and their corticotropin releasing factor antagonistic activity. Furthermore, astressin and its analogs were studied by CD in order to determine the secondary structure in solution. Since the linear form of astressin and also the cyclic inverso isomer were found to be fully inactive, it can be concluded that a cyclic constraint and a right‐handed α‐helix, respectively, are of utmost importance for these peptides to act as corticotropin releasing factor antagonists. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 141–149, 2002