Pure glucagon antagonists: Biological activities and camp accumulation using phosphodiesterase inhibitors

Bassem Y. Azizeh, Brian A. Van Tine, Dev Trivedi, Victor J. Hruby

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Five new glucagon analogues have been designed, synthesized, characterized and their biological activities tested. The investigation was centered on modifications in the N-terminal region in particular, residues at Thr5, Phe6 and Tyr10 positions, with the goal of obtaining pure glucagon antagonists in our newly developed high sensitivity cAMP accumulation assay. The structures of the designed compounds are: [des-His1, des-Phe6. Glu9 ]glucagon-NH2 (1); [des-His1, des-Phe6, Glu9, Phe10] glucagon-NH2 (2): [des-His1, Tyr5, des-Phe6, Glu9] glucagon NH2 (3): [des-His1, Phe5, des-Phe6, Glu9]glucagon-NH2 (4) and [des-His1, des-Phe6, Glu9, D- Arg18]glucagon-NH2 (5). The binding potencies IC50 values in (nM) were 48.0, 27.4, 26.0, 20.0 and 416.0, respectively. All of these analogues when tested in the classical adenylate cyclase assay demonstrate antagonist properties, and in competition experiments, all caused a right-wardshift of the glucagon stimulated adenylate cyclase dose-response curve. The pA2 values for these analogues were 8.20 (1); 6.25 (2): 6.10 (3); 6.25 (4); and 6.08 (5), respectively. A newly revised assay has been developed to determine the intracellular cAMP accumulation levels in hepatocytes at the highest possible sensitivity. Four of the five glucagon analogues in this report (analogues 1, 2, 4 and 5), did not activate the adenylate cyclase in the presence of Rolipram up to a maximal physiological concentration of 1 μM, and thus are pure antagonists.

Original languageEnglish (US)
Pages (from-to)633-641
Number of pages9
JournalPeptides
Volume18
Issue number5
DOIs
StatePublished - Aug 12 1997

Keywords

  • Adenylate cyclase
  • Amrinone
  • Glucagon antagonists
  • Hepatocytes
  • IBMX
  • Phosphodiesterase inhibitors
  • Receptor binding
  • Rolipram
  • Structure-activity relationships
  • cAMP accumulation

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Endocrinology
  • Cellular and Molecular Neuroscience

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