Book Description

Mass spectrometry-based techniques have emerged as powerful analytical tools to investigate the structure of proteins from the primary to quaternary levels. The advancement of mass spectrometry instrumentation and methods has allowed researchers to go beyond just measuring an analyte’s mass-to-charge ratio, but to also probe gas-phase dissociation behaviors and conformations of peptides, proteins, and protein complexes. The primary structure of a protein refers to the linear sequence of amino acids linked together via peptide bonds. The presence, and the order, of specific amino acids in a peptide can strongly influence how a peptide fragments in the gas-phase. Particular amino acids can direct where along the peptide backbone fragmentation is favored and the structure of the fragment ions formed. One method for probing the structure of peptide fragment ions is infrared multiphoton dissociation (IRMPD) mass spectrometry coupled with theoretical quantum chemical calculations. This approach is used to investigate the role of peptide bond conformation on the structure of b2+ fragment ions formed from proline and dimethylproline-containing peptides (Chapter 3). Additionally, IRMPD is used to study the fragmentation patterns of proline containing pentapeptides into b3+ ions (Chapter 4). Native mass spectrometry (nMS) analyzes the intact structures of proteins and protein complexes and offers complementary information to traditional biophysical methods, such as NMR or cryo-EM. Tandem mass spectrometry, specifically surface-induced dissociation (SID), provides information on protein complex connectivity, stoichiometry, and gas-phase structural rearrangement. SID is utilized to monitor deviation from native structure for protein complexes generated from submicrometer nanoelectrospray capillaries (Chapter 5), as well as to provide insight into connectivity of protein complexes selected by trapped ion mobility spectrometry (Chapter 6). In addition to SID, ion mobility spectrometry provides information on the gas-phase shape or conformation of biomolecules. Here, ion mobility spectrometry is utilized to separate multiple conformers of proline-containing peptides (Chapter 3), compare the collision cross sections of protein complexes generated from submicrometer and micrometer sized nanoelectrospray capillaries (Chapter 5), and select protein complexes and isomeric peptides prior to dissociation on an ultrahigh resolution mass spectrometry platform (Chapter 6). Finally, the development and optimization of Trapped Ion Mobility Spectrometry (TIMS) for native mass spectrometry applications is applied to the widely available timsTOF Pro mass spectrometry platform to promote the dissemination of native ion mobility technology.