Design of benzophenone-containing photoactivatable linear vasopressin antagonists: pharmacological and photoreactive properties.
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.
Ponthieux
Sylvie
S
CNRS UPR9023 and INSERM U469, IGF, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France.
Cabot
Joëlle
J
Mouillac
Bernard
B
Seyer
René
R
Barberis
Claude
C
Carnazzi
Eric
E
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
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