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How to deal with weak interactions in noncovalent complexes analyzed by electrospray mass spectrometry: Cyclopeptidic inhibitors of the nuclear receptor coactivator 1-STAT6

Touboul, David ; Maillard, Ludovic ; Grässlin, Anja ; Moumne, Roba ; Seitz, Markus ; Robinson, John ; Zenobi, Renato

In: Journal of the American Society for Mass Spectrometry, 2009, vol. 20, no. 2, p. 303-311

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    Titel
    • How to deal with weak interactions in noncovalent complexes analyzed by electrospray mass spectrometry: Cyclopeptidic inhibitors of the nuclear receptor coactivator 1-STAT6
    Autor
    • Touboul, David. Department of Chemistry and Applied Biosciences, ETH Zürich, ETH Honggerberg, HCI E 329, CH-8093, Zürich, Switzerland
    • Maillard, Ludovic. Institute of Organic Chemistry, University of Zürich, Zürich, Switzerland
    • Grässlin, Anja. Institute of Organic Chemistry, University of Zürich, Zürich, Switzerland
    • Moumne, Roba. Institute of Organic Chemistry, University of Zürich, Zürich, Switzerland
    • Seitz, Markus. Institute of Organic Chemistry, University of Zürich, Zürich, Switzerland
    • Robinson, John. Institute of Organic Chemistry, University of Zürich, Zürich, Switzerland
    • Zenobi, Renato. Department of Chemistry and Applied Biosciences, ETH Zürich, ETH Honggerberg, HCI E 329, CH-8093, Zürich, Switzerland
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Journal of the American Society for Mass Spectrometry, 2009, vol. 20, no. 2, p. 303-311. Springer-Verlag
    Andere elektronische Ausgabe
    Klassifikation
    • Chemie
    OAI-PMH-ID
    • oai:doc.rero.ch:312365
    Summary
    Mass spectrometry, and especially electrospray ionization, is now an efficient tool to study noncovalent interactions between proteins and inhibitors. It is used here to study the interaction of some weak inhibitors with the NCoA-1/STAT6 protein with K D values in the µM range. High signal intensities corresponding to some nonspecific electrostatic interactions between NCoA-1 and the oppositely charged inhibitors were observed by nanoelectrospray mass spectrometry, due to the use of high ligand concentrations. Diverse strategies have already been developed to deal with nonspecific interactions, such as controlled dissociation in the gas phase, mathematical modeling, or the use of a reference protein to monitor the appearance of nonspecific complexes. We demonstrate here that this last methodology, validated only in the case of neutral sugar-protein interactions, i.e., where dipole-dipole interactions are crucial, is not relevant in the case of strong electrostatic interactions. Thus, we developed a novel strategy based on half-maximal inhibitory concentration (IC50) measurements in a competitive assay with readout by nanoelectrospray mass spectrometry. IC50 values determined by MS were finally converted into dissociation constants that showed very good agreement with values determined in the liquid phase using a fluorescence polarization assay