Effect of phenylalanine on the fragmentation of deprotonated peptides |
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Authors: | Harrison Alex G |
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Institution: | Department of Chemistry, University of Toronto, Ontario, Canada. aharriso@utoronto.ca |
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Abstract: | The fragmentation reactions of a variety of deprotonated dipeptides and tripeptides containing phenylalanine have been studied using energy-resolved collision-induced dissociation, isotopic labeling and MS/MS/MS experiments. The benzyl a-group has a substantial effect on the fragmentation reactions observed. When the phenylalanine is in the C-terminal position of dipeptides or tripeptides a major fragmentation reaction is elimination of neutral cinnamic acid to from a deprotonated amino acid amide (c1 ion) for dipeptides and a deprotonated dipeptide amide (c2 ion) for tripeptides. Fragmentation of the M - H]- ions of tripeptides with phenylalanine in the central position also results in substantial formation of the deprotonated amide of the N-terminal amino acid residue. When the phenylalanine residue is in the N-terminal position elimination of C7H8 from the M - H - CO2]- ion and formation of the benzyl anion become important fragmentation pathways. Sequence ions frequently observed are the y1 ions, "b2 ions and a3-Nt ions. |
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