Ion Mobility-Mass Spectrometry as a Tool for the Structural Characterization of Peptides Bearing Intramolecular Disulfide Bond(s)

Disulfide bonds are post-translationnal modifications that can be crucial for the stability and the biological activities of natural peptides. Considering the importance of these disulfide bond-containing peptides, the development of new techniques in order to characterize these modifications is of great interest. For this purpose, collision cross cections (CCS) of a large data set of 118 peptides (displaying various sequences) bearing zero, one, two, or three disulfide bond(s) have been measured in this study at different charge states using ion mobility-mass spectrometry. From an experimental point of view, CCS differences (Delta CCS) between peptides bearing various numbers of disulfide bonds and peptides having no disulfide bonds have been calculated. The Delta CCS calculations have also been applied to peptides bearing two disulfide bonds but different cysteine connectivities (Cys1-Cys2/Cys3-Cys4; Cys1-Cys3/Cys2-Cys4; Cys1-Cys4/Cys2-Cys3). The effect of the replacement of a proton by a potassium adduct on a peptidic structure has also been investigated.