Synthesis and characterization of arylamine derivatives of rauwolscine as molecular probes for α<inf>2</inf>-adrenergic receptors

Stephen M. Lanier, Robert M. Graham, Hans Ju¨rgen Hess, Alex Grodski, Mary G. Repaske, Jodi M. Nunnari, Lee E. Limbird, Charles J. Homcy

Research output: Contribution to journalArticle

Abstract

The selective α<inf>2</inf>-adrenergic receptor antagonist rauwolscine was structurally modified to yield a series of arylamine carboxamide derivatives, which were investigated as potential molecular probes for the localization and structural characterization of α<inf>2</inf>-adrenergic receptors. The arylamine carboxamides differ in the number of carbon atoms separating the reactive phenyl moiety from the fused ring structure of the parent compound, rauwolscine carboxylate. Competitive inhibition studies with [<sup>3</sup>H]rauwolscine in rat kidney membranes indicate that the affinity for the carboxamide derivatives is inversely related to the length of the carbon spacer arm with rauwolscine 4-aminophenyl carboxamide (zero carbon spacer arm; rau-AMPC) exhibiting the highest affinity (K<inf>d</inf> = 2.3 ± 0.2 nM). Radioiodination of rau-AMPC yields a ligand, <inf>125</inf>I-rau-AMPC, which binds to rat kidney α<inf>2</inf>-adrenergic receptors with high affinity, as determined by both kinetic analysis (K<inf>d</inf> = k<inf>2</inf>/k<inf>1</inf> = 0.016 min<sup>-1</sup>/2.1 × 10<sup>-7</sup> min <sup>-1</sup>= 0.76 nM) and equilibrium binding studies (K<inf>d</inf> = 0.78 ± 0.16 nM). 125Irau-AMPC was quantitatively converted to the photolabile arylazide derivative 17α-hydroxy-20ayohimban-16β-(N-4-azido-3-[<sup>125</sup>I]iodophenyl)carboxamide (<sup>125</sup>I-rau-AZPC). In a partially purified receptor preparation from porcine brain, this compound photolabels a major (M<inf>r</inf> = 62,000) peptide. The labeling of this peptide is inhibited by adrenergic agonists and antagonists with a rank order of potency consistent with an a<inf>2</inf>-adrenergic receptor binding site. Both <sup>125</sup>I-rau-AMPC and the photolabile arylazide derivative, <sup>l25</sup>I-rau-AZPC, should prove useful as molecular probes for the structural and biochemical characterization of α<inf>2</inf>-adrenergic receptors.

Original languageEnglish (US)
Pages (from-to)III-120-III-124
JournalHypertension
Volume9
Issue number6, Part 2
StatePublished - 1987
Externally publishedYes

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Molecular Probes
Yohimbine
Adrenergic Receptors
Adrenergic Antagonists
Carbon
Kidney
Adrenergic Agonists
Peptides
Swine
Binding Sites
Ligands
Membranes
Brain
17-hydroxy-20-yohimban-16-(N-(4-azido-3-iodo)phenyl)carboxamide

Keywords

  • Photoaffinity label
  • Porcine brain
  • Rauwolscine
  • α<inf>2</inf>-adrenergic receptors

ASJC Scopus subject areas

  • Internal Medicine

Cite this

Lanier, S. M., Graham, R. M., Hess, H. J., Grodski, A., Repaske, M. G., Nunnari, J. M., ... Homcy, C. J. (1987). Synthesis and characterization of arylamine derivatives of rauwolscine as molecular probes for α<inf>2</inf>-adrenergic receptors. Hypertension, 9(6, Part 2), III-120-III-124.

Synthesis and characterization of arylamine derivatives of rauwolscine as molecular probes for α<inf>2</inf>-adrenergic receptors. / Lanier, Stephen M.; Graham, Robert M.; Hess, Hans Ju¨rgen; Grodski, Alex; Repaske, Mary G.; Nunnari, Jodi M.; Limbird, Lee E.; Homcy, Charles J.

In: Hypertension, Vol. 9, No. 6, Part 2, 1987, p. III-120-III-124.

Research output: Contribution to journalArticle

Lanier, SM, Graham, RM, Hess, HJ, Grodski, A, Repaske, MG, Nunnari, JM, Limbird, LE & Homcy, CJ 1987, 'Synthesis and characterization of arylamine derivatives of rauwolscine as molecular probes for α<inf>2</inf>-adrenergic receptors', Hypertension, vol. 9, no. 6, Part 2, pp. III-120-III-124.
Lanier SM, Graham RM, Hess HJ, Grodski A, Repaske MG, Nunnari JM et al. Synthesis and characterization of arylamine derivatives of rauwolscine as molecular probes for α<inf>2</inf>-adrenergic receptors. Hypertension. 1987;9(6, Part 2):III-120-III-124.
Lanier, Stephen M. ; Graham, Robert M. ; Hess, Hans Ju¨rgen ; Grodski, Alex ; Repaske, Mary G. ; Nunnari, Jodi M. ; Limbird, Lee E. ; Homcy, Charles J. / Synthesis and characterization of arylamine derivatives of rauwolscine as molecular probes for α<inf>2</inf>-adrenergic receptors. In: Hypertension. 1987 ; Vol. 9, No. 6, Part 2. pp. III-120-III-124.
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abstract = "The selective α2-adrenergic receptor antagonist rauwolscine was structurally modified to yield a series of arylamine carboxamide derivatives, which were investigated as potential molecular probes for the localization and structural characterization of α2-adrenergic receptors. The arylamine carboxamides differ in the number of carbon atoms separating the reactive phenyl moiety from the fused ring structure of the parent compound, rauwolscine carboxylate. Competitive inhibition studies with [3H]rauwolscine in rat kidney membranes indicate that the affinity for the carboxamide derivatives is inversely related to the length of the carbon spacer arm with rauwolscine 4-aminophenyl carboxamide (zero carbon spacer arm; rau-AMPC) exhibiting the highest affinity (Kd = 2.3 ± 0.2 nM). Radioiodination of rau-AMPC yields a ligand, 125I-rau-AMPC, which binds to rat kidney α2-adrenergic receptors with high affinity, as determined by both kinetic analysis (Kd = k2/k1 = 0.016 min-1/2.1 × 10-7 min -1= 0.76 nM) and equilibrium binding studies (Kd = 0.78 ± 0.16 nM). 125Irau-AMPC was quantitatively converted to the photolabile arylazide derivative 17α-hydroxy-20ayohimban-16β-(N-4-azido-3-[125I]iodophenyl)carboxamide (125I-rau-AZPC). In a partially purified receptor preparation from porcine brain, this compound photolabels a major (Mr = 62,000) peptide. The labeling of this peptide is inhibited by adrenergic agonists and antagonists with a rank order of potency consistent with an a2-adrenergic receptor binding site. Both 125I-rau-AMPC and the photolabile arylazide derivative, l25I-rau-AZPC, should prove useful as molecular probes for the structural and biochemical characterization of α2-adrenergic receptors.",
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