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Tandem mass spectrometry for the determination of the intrinsic interactions of metal ions with and the sequence of peptides
Abstract
The major part of this dissertation deals with the interactions of metal ions and peptides in the metal-bound peptides and bis(peptide) complexes. The study of those complexes by tandem mass spectrometry reveals that alkaline earth and alkali metal ions are intrinsically able to induce peptide deprotonation and form gas-phase complexes that do not occur in solution. Transition metal ion/peptide complexes, on the other hand, do form in solution and in the gas phase. The solution-phase complexes differ from those observed in the gas phase; both the relative acidity of the ligands and the ligand affinity of the metal ions affect the metal bonding structures of the complexes. Peptide side chains become vulnerable to collisional activation under the influences of the complexing metal ion; in fact, doubly charged metal ions chelate to aromatic side chains directly in the metal-cationized peptides. The second part of the dissertation discusses the application of mass spectrometry to the structure characterization of peptides. The sequence of five synthetic phenylalanine-containing peptides was established by interpretation of the CAD spectra of their (M + H)$\sp+$ ions. Three natural frog peptides and their synthetic analogues were studied in order to establish structure identities. A novel structure is proposed for the water loss product; it is formed by the cyclization of an aspartic side chain acid. Further, alpha aspartyl peptides can be distinguished from beta aspartyl isomers on the basis of the relative abundance of the b$\sb{\rm n}$ and a$\sb{\rm n}$ ions that are produced from the decomposition of the aspartic residue.
Subject Area
Analytical chemistry
Recommended Citation
Hu, Peifeng, "Tandem mass spectrometry for the determination of the intrinsic interactions of metal ions with and the sequence of peptides" (1993). ETD collection for University of Nebraska-Lincoln. AAI9331419.
https://digitalcommons.unl.edu/dissertations/AAI9331419