Gas-phase ion/ion and dissociation reactions in a quadrupole ion trap: Protein and peptide cation dissociation and reactions with metal -ligand anions
Abstract
Investigations of the behavior of gaseous polypeptide cations when subjected to manipulation by collision-induced dissociation (CID) and ion/ion reactions in a quadrupole ion trap mass spectrometer are performed. In these studies, the unique capability of the ion trap to serve as both a reaction vessel and a mass analyzer is utilized as well as the ability to perform tandem-in-time experiments. If gas-phase protein ion fragmentation is to be used as a general tool for protein characterization and identification, an exploration of variables influencing the fragmentation observed from CID of multiply-charged protein ions is required. The first part of the current thesis work includes the systematic examination of factors expected to impact fragmentation behavior of multiply-protonated, intact protein ions. The results from the investigations within indicate that the fragmentation observed is more dependent on parent ion charge state and properties of the protein, such as post-translational modifications, than collisional activation conditions. The ability to form a variety of peptide/protein ions with various cationizing reagents in the gas phase is attractive both for the study of intrinsic interactions of metal ions with polypeptides and for maximizing the structural information available from tandem mass spectrometry experiments. As part of the current thesis work, methodologies involving gas-phase ion/ion reactions for generating and manipulating metal containing polypeptide ions are described. Properties of the metal anionic reagent and the peptide affect the types of reaction products observed. These approaches afford a high degree of flexibility in forming metal containing polypeptide ions and facilitate comparisons of CID behavior of polypeptide ions formed by a variety of techniques. Thus far, there are no major differences in the fragmentation observed from ion trap collisional activation of the same nominal ion formed via different methods.
Degree
Ph.D.
Advisors
McLuckey, Purdue University.
Subject Area
Analytical chemistry
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