title: Design of benzophenone-containing photoactivatable linear vasopressin antagonists: pharmacological and photoreactive properties.
abstract: We designed and synthesized new photoactivatable linear vasopressin analogues containing benzophenone photophores. All compounds were monitored and purified using RP-HPLC and characterized by mass spectrometry. Affinity and selectivity were determined in CHO cells expressing either human V(1a), V(1b) or V(2) receptor subtypes. Within the series, compounds 6 (PhCH(2)CO-lBpa-Phe-Gln-Asn-Arg-Pro-Arg-Tyr(3I)-NH(2)) and 9 (PhCH(2)CO-dBpa-Phe-Gln-Asn-Arg-Pro-Arg-Tyr(3I)-NH(2)), containing a benzoylphenylalanine residue (Bpa), were selected and their antagonistic properties determined (K(inact) = 1.87 and 0.35 nM, respectively). The dissociation constant of the most potent candidate (compound 9) was further calculated from saturation experiments using the (125)I derivative (K(d) = 0.07 +/- 0.01 nM). Photolabeling experiments using radioactive compound 9 as a probe were specific and UV-dependent and allowed the identification of two bands at molecular masses around 85-90 kDa and 46 kDa, respectively, as previously described by Phalipou et al., using two photoreactive linear azidopeptide antagonists. The results suggest therefore that compound 9 is a potent new tool for the accurate mapping of the human V(1a) receptor antagonist binding site.
authors.affiliation: CNRS UPR9023 and INSERM U469, IGF, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Ponthieux
authors.forename: Joëlle
authors.initials: J
authors.lastname: Cabot
authors.forename: Bernard
authors.initials: B
authors.lastname: Mouillac
authors.forename: René
authors.initials: R
authors.lastname: Seyer
authors.forename: Claude
authors.initials: C
authors.lastname: Barberis
authors.forename: Eric
authors.initials: E
authors.lastname: Carnazzi
mesh_terms: D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001577:Benzophenones / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007457:Iodine Radioisotopes; D007700:Kinetics; D008027:Light; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D019920:Photoaffinity Labels / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011869:Radioligand Assay; D017483:Receptors, Vasopressin / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D001577:Benzophenones; D007457:Iodine Radioisotopes; D009842:Oligopeptides; D019920:Photoaffinity Labels; D017483:Receptors, Vasopressin; C500852:benzylcarbonyl-4-benzoylphenylalanyl-phenylalanyl-glutaminyl-asparaginyl-arginyl-prolyl-arginyl-3-iodotyrosinamide