Differentiation of Aspartic and Isoaspartic Acids Using Electron Transfer Dissociation

• Published in: Journal of the American Society for Mass Spectrometry 2006-01, Vol.17 (1), p.15-19
• Main Authors: O’Connor, Peter B., Cournoyer, Jason J., Pitteri, Sharon J., Chrisman, Paul A., McLuckey, Scott A.
• Format: Article
• Language: English
• Subjects: Acids; Aminoacids, peptides. Hormones. Neuropeptides; Analytical, structural and metabolic biochemistry; ASPARTIC ACID; Aspartic Acid - chemistry; ATOMIC AND MOLECULAR PHYSICS; Beta decay; Biological and medical sciences; Chemistry; Diagnostic systems; Differentiation; DISSOCIATION; ELECTRON CAPTURE; ELECTRON TRANSFER; Electrons; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Indicators and Reagents; IONS; Isoaspartic Acid - chemistry; Mass Spectrometry; MASS SPECTROSCOPY; Organic chemistry; Peptides - chemistry; Proteins; Reactivity and mechanisms; Residues; TRAPS
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1016/j.jasms.2005.08.019

Electron-transfer dissociation allows differentiation of isoaspartic acid and aspartic acid residues using the same c + 57 and z − 57 peaks that were previously observed with electron capture dissociation. These peaks clearly define both the presence and the position of isoaspartic acid residues and they are relatively abundant. The lower resolution of the ion trap instrument makes detection of the aspartic acid residue’s diagnostic peak difficult because of interference with side-chain fragment ions from arginine residues, but the aspartic acid residues are still clearly observed in the backbone cleavages and can be inferred from the absence of the isoaspartic acid diagnostic ions.