title: Differentiation of aspartic and isoaspartic acids using electron transfer dissociation.
abstract: 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.
authors.affiliation: Mass Spectrometry Resource, Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, 2118, Boston, MA, USA. poconnor@bu.edu.
authors.forename: Peter B
authors.initials: PB
authors.lastname: O'Connor
authors.affiliation: Mass Spectrometry Resource, Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, 2118, Boston, MA, USA.
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Cournoyer
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana, USA.
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Pitteri
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana, USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Chrisman
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: McLuckey
mesh_terms: D001224:Aspartic Acid / Q000737:chemistry*; D004583:Electrons; D007202:Indicators and Reagents; D026581:Isoaspartic Acid / Q000737:chemistry*; D013058:Mass Spectrometry; D010455:Peptides / Q000737:chemistry
chemical_list: D007202:Indicators and Reagents; D026581:Isoaspartic Acid; D010455:Peptides; D001224:Aspartic Acid