title: Energetics and structural characterization of isomers using ion mobility and gas-phase H/D exchange: Learning from lasso peptides.
abstract: State-of-the-art characterization of proteins using MS namely relies on fragmentation methods that allow exploring featured dissociative reaction pathways. These pathways are often initiated by a series of potentially informative mass-constant conformational changes that are nonetheless frequently overlooked by lack of adequate investigation techniques. In the present study, we propose a methodology to readily address both structural and energetic aspects of stereoisomerization reactions using ion mobility coupled with MS. To this end, a commercial spectrometer was used as a reactor comprising an energy resolved collisional activation step intended at promoting controlled conformational changes and a structural assignment step dedicated to the identification of the generated isomers. This identification relies on ion mobility and other on-line coupled techniques, namely an originally designed gas-phase H/D exchange experiment. We here apply this methodology to characterize the isomerization kinetics of capistruin, a 19-residue long lasso-folded peptide. We expect this approach to bring insights into the physical origin of global dissociation thresholds monitored in MS/MS experiments and to set a promising basis for quantitative investigations of the stability of different molecular folds.
authors.affiliation: Mass Spectrometry Laboratory, Department of Chemistry, University of Liege, Liege, Belgium.
authors.forename: Emeline
authors.initials: E
authors.lastname: Hanozin
authors.affiliation: Mass Spectrometry Laboratory, Department of Chemistry, University of Liege, Liege, Belgium.
authors.forename: Denis
authors.initials: D
authors.lastname: Morsa
authors.affiliation: Mass Spectrometry Laboratory, Department of Chemistry, University of Liege, Liege, Belgium.
authors.forename: Edwin
authors.initials: E
authors.lastname: De Pauw
mesh_terms: D000595:Amino Acid Sequence; D041961:Deuterium Exchange Measurement / Q000379:methods*; D007536:Isomerism; D013058:Mass Spectrometry / Q000379:methods*; D010455:Peptides / Q000737:chemistry*; D015203:Reproducibility of Results; D013816:Thermodynamics
chemical_list: D010455:Peptides; C533129:capistruin
keywords: Capistruin; Energy calibration; Enthalpy; Entropy; Relay mechanism; Technology