Development of a biologically active secretin analogue incorporating a radioiodinatable photolabile p-(4-hydroxybenzoyl)phenylalanine in position 10

Maoqing Dong, Delia I. Pinon, Laurence J. Miller

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Photoaffinity labeling is a powerful approach for direct elucidation of residue-residue approximations as a ligand is bound to its receptor, providing important constraints for molecular modeling. Probes utilized for this need to incorporate photolabile sites of covalent attachment and an indicator, such as a radiolabel. Radioiodine provides a particularly useful high specific radioactivity label, but due to its size, can only be accommodated in limited positions within a peptide ligand. In this work, we attempted to develop a probe for the secretin receptor that would directly provide spatial approximation data for position 10 of secretin, its site of radiolabeling. This was achieved by incorporation into a secretin analogue of the radioiodinatable and photolabile benzophenone moiety, p-(4-hydroxybenzoyl)phenylalanine (OH-Bpa). An unintended additional modification of secretin in synthesizing this probe was the elimination of Gly4. This probe was shown to bind to the secretin receptor specifically and saturably (Ki=25.3±6.0 nM). It represented a full agonist, stimulating intracellular cAMP in a concentration-dependent manner (EC50=4.2±0.7 nM). It was also able to affinity label the secretin receptor in a specific and efficient manner. This probe should provide the opportunity to identify the region of the secretin receptor in spatial approximation with position 10, within the pharmacophore of secretin, leading to refinement of molecular conformational models of this agonist-bound receptor.

Original languageEnglish (US)
Pages (from-to)181-187
Number of pages7
JournalRegulatory Peptides
Volume109
Issue number1-3
DOIs
StatePublished - Nov 15 2002

Keywords

  • (Benzoyl)phenylalanine
  • (Hydroxybenzoyl)phenylalanine
  • Class II G protein-coupled receptor
  • Ligand-binding domain
  • Photoaffinity labeling
  • Secretin receptor

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Endocrinology
  • Clinical Biochemistry
  • Cellular and Molecular Neuroscience

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