A Conformation-Specific\nApproach to Native Top-down\nMass Spectrometry

Native\ntop-down mass spectrometry is a powerful approach for characterizing\nproteoforms and has recently been applied to provide similarly powerful\ninsights into protein conformation. Current approaches, however, are\nlimited such that structural insights can only be obtained for the\nentire conformational landscape in bulk or without any direct conformational\nmeasurement. We report a new ion-mobility-enabled method for performing\nnative top-down MS in a conformation-specific manner. Our approach\nidentified conformation-linked differences in backbone dissociation\nfor the model protein calmodulin, which simultaneously informs upon\nproteoform variations and provides structural insights. We also illustrate\nthat our method can be applied to protein–ligand complexes,\neither to identify components or to probe ligand-induced structural\nchanges.