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Development of Photoactivatable Allosteric Modulators for the Chemokine Receptor CXCR3
Author(s) -
Admas Tizita Haimanot,
Bernat Viachaslau,
Heinrich Markus R.,
Tschammer Nuska
Publication year - 2016
Publication title -
chemmedchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.817
H-Index - 100
eISSN - 1860-7187
pISSN - 1860-7179
DOI - 10.1002/cmdc.201500573
Subject(s) - allosteric regulation , chemistry , photoaffinity labeling , cxcr3 , g protein coupled receptor , allosteric modulator , receptor , ligand (biochemistry) , radioligand , trifluoromethyl , stereochemistry , biophysics , biochemistry , combinatorial chemistry , chemokine receptor , chemokine , biology , organic chemistry , alkyl
The CXCR3 receptor, a class A G protein‐coupled receptor (GPCR), is involved in the regulation and trafficking of various immune cells. CXCR3 antagonists have been proposed to be beneficial for the treatment of a wide range of disorders including but not limited to inflammatory and autoimmune diseases. The structure‐based design of CXCR3 ligands remains, however, hampered by a lack of structural information describing in detail the interactions between an allosteric ligand and the receptor. We designed and synthesized photoactivatable probes for the structural and functional characterization, using photoaffinity labeling followed by mass spectrometry, of the CXCR3 allosteric binding pocket of AMG 487 and RAMX3, two potent and selective CXCR3 negative allosteric modulators. Photoaffinity labeling is a common approach to elucidate binding modes of small‐molecule ligands of GPCRs through the aid of photoactivatable probes that convert to extremely reactive intermediates upon photolysis. The photolabile probe N ‐[({1‐[3‐(4‐ethoxyphenyl)‐4‐oxo‐3,4‐dihydropyrido[2,3‐ d ]pyrimidin‐2‐yl]ethyl}‐2‐[4‐fluoro‐3‐(trifluoromethyl)phenyl]‐ N ‐{1‐[4‐(3‐(trifluoromethyl)‐3 H ‐diazirin‐3‐yl]benzyl}piperidin‐4‐yl)methyl]acetamide ( 10 ) showed significant labeling of the CXCR3 receptor (80 %) in a [ 3 H]RAMX3 radioligand displacement assay. Compound 10 will serve as an important tool compound for the detailed investigation of the binding pocket of CXCR3 by mass spectrometry.