Mass spectrometric investigation of metal/peptide and metal/protein interactions

One theme of this dissertation is the interaction of ions Ca{dollar}sp{lcub}2+{rcub}{dollar} ions with peptides and proteins. The study of the intrinsic Ca{dollar}sp{lcub}2+{rcub}{dollar}-affinities of synthetic peptides that are analogues of Ca{dollar}sp{lcub}2+{rcub}{dollar}-binding site III of rabbit skeletal troponin C were evaluated by tandem mass spectrometry by using the kinetic method and found to be in a different order than that for peptides in solution. The same peptides were studied by tandem mass spectrometry, and Ca{dollar}sp{lcub}2+{rcub}{dollar}-binding sites were found to involve the acidic amino acids and their amides.; Mass spectrometry methods were then extended to investigation of the interaction of calcium with calmodulin and its subsequent binding to peptides. The interactions of calmodulin with Ca{dollar}sp{lcub}2+{rcub}{dollar} and then with peptides were studied by electrospray ionization mass spectrometry, and conformational changes of calmodulin were assessed by hydrogen/deuterium exchange.; The second part of the dissertation discusses the interactions of iron with cysteine-containing peptides that were probed by fast atom bombardment and tandem mass spectrometry. The interaction of iron with cysteine-containing peptides was found to be sufficiently strong and specific that it is preserved upon activation, giving information on the location of the cysteine residue in the peptide chain and the nature of the bonding of Fe{dollar}sp{lcub}2+{rcub}{dollar} to cysteine-containing peptides.