DEVELOPMENT OF GAS-PHASE ION/ION REACTIONS FOR CHARACTERIZING PROTEIN AND PEPTIDE IONS

Mass spectrometry-based gas-phase ion/ion reactions have grown considerably in the last decade. Their applications range from structural elucidation, instrument calibration, and spectral deconvolution. One field that has been amenable to these methods is proteomic studies. Proteins and peptides have grown as candidates for biomarkers and vaccines. Proteins are vastly different with mass ranging from 1 kDa to well over 1 MDa and various types of post translational modifications. The structural heterogeneity that proteins can exhibit demonstrates the need for high resolution mass spectrometry methods. The combination of native mass spectrometry and soft ionization sources allow for preservation of structures seen in solution as analytes enter the gas phase. By developing methods that probe these structures, the information gathered can be related to the native structures in solution. Here I show, gas phase ion/ion reactions that can be utilized for location of salt bridge structures, gas-phase crosslinking of homo and heterodimer protein complexes, and mass determination of large (>800 kDa) protein complexes. These methods allow for greater control, faster data acquisition, and minimal sample preparation. These methods were developed on modified Sciex TripleTOF 5600 and 4000 QTRAP tandem mass spectrometers.