title: Ion Mobility-Mass Spectrometry Differentiates Protein Quaternary Structures Formed in Solution and in Electrospray Droplets.
abstract: Electrospray ionization coupled to mass spectrometry is a key technology for determining the stoichiometries of multiprotein complexes. Despite highly accurate results for many assemblies, challenging samples can generate signals for artifact protein-protein binding born of the crowding forces present within drying electrospray droplets. Here, for the first time, we study the formation of preferred protein quaternary structures within such rapidly evaporating nanodroplets. We use ion mobility and tandem mass spectrometry to investigate glutamate dehydrogenase dodecamers and serum amyloid P decamers as a function of protein concentration, along with control experiments using carefully chosen protein analogues, to both establish the formation of operative mechanisms and assign the bimodal conformer populations observed. Further, we identify an unprecedented symmetric collision-induced dissociation pathway that we link directly to the quaternary structures of the precursor ions selected.
authors.affiliation: Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States.
authors.forename: Linjie
authors.initials: L
authors.lastname: Han
authors.affiliation: Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States.
authors.forename: Brandon T
authors.initials: BT
authors.lastname: Ruotolo
mesh_terms: D013058:Mass Spectrometry / Q000379:methods*; D020836:Protein Structure, Quaternary; D021241:Spectrometry, Mass, Electrospray Ionization