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Lim K.S.,Seoul National University | Lee H.,Seoul National University | Kim S.E.,Seoul National University | Ha T.-H.,Seoul National University | And 9 more authors.
European Journal of Medicinal Chemistry | Year: 2013

A series of carbonate analogues of 5′-halogenated RTX have been investigated in order to examine the effect of the carbonate group as a linker and the role of halogens in the reversal of activity from agonism to antagonism for rat and human TRPV1 heterologously expressed in Chinese hamster ovary cells. The carbonate analogues showed similar activities to the corresponding RTX derivatives in rat TRPV1 but lower potency in human TRPV1. 5-Halogenation converted the agonists to partial agonists or full antagonists and the extent of antagonism reflected the order of I > Br > Cl > F, with a somewhat greater extent of antagonism for the derivatives of the 4-amino RTX surrogates compared to the corresponding derivatives of RTX itself. The carbonate analogues of I-RTX (60) and 5-bromo-4-amino-RTX (66) were potent and full antagonists with Ki(ant) = 2.23 and 2.46 nM, respectively, for rat TRPV1, which were ca. 5-fold more potent than I-RTX (2) under our conditions. The conformational analysis of the I-RTX-carbonate (60) indicated that its bent conformation was similar to that of I-RTX, consistent with compound 60 and I-RTX showing comparable potent antagonism. © 2013 Elsevier Masson SAS. All rights reserved. Source

Lee Y.,National Leading Research Laboratory NLRL of Molecular Modeling and Drug Design | Lee Y.,Ewha Womans University | Choi S.,National Leading Research Laboratory NLRL of Molecular Modeling and Drug Design | Choi S.,Ewha Womans University | Hyeon C.,Korea Institute for Advanced Study
Proteins: Structure, Function and Bioinformatics | Year: 2014

G-protein coupled receptors (GPCRs), a major gatekeeper of extracellular signals on plasma membrane, are unarguably one of the most important therapeutic targets. Given the recent discoveries of allosteric modulations, an allosteric wiring diagram of intramolecular signal transductions would be of great use to glean the mechanism of receptor regulation. Here, by evaluating betweenness centrality (CB) of each residue, we calculate maps of information flow in GPCRs and identify key residues for signal transductions and their pathways. Compared with preexisting approaches, the allosteric hotspots that our CB-based analysis detects for A2A adenosine receptor (A2AAR) and bovine rhodopsin are better correlated with biochemical data. In particular, our analysis outperforms other methods in locating the rotameric microswitches, which are generally deemed critical for mediating orthosteric signaling in class A GPCRs. For A2AAR, the inter-residue cross-correlation map, calculated using equilibrium structural ensemble from molecular dynamics simulations, reveals that strong signals of long-range transmembrane communications exist only in the agonist-bound state. A seemingly subtle variation in structure, found in different GPCR subtypes or imparted by agonist bindings or a point mutation at an allosteric site, can lead to a drastic difference in the map of signaling pathways and protein activity. The signaling map of GPCRs provides valuable insights into allosteric modulations as well as reliable identifications of orthosteric signaling pathways. © 2013 Wiley Periodicals, Inc. Source

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