title: Distinction of alpha- and beta-aspartyl and alpha- and gamma-glutamyl peptides by fast atom bombardment/tandem mass spectrometry.
abstract: A fast atom bombardment/collisional activation/linked-scan at constant B/E (tandem mass spectrometric) method is described which can distinguish between alpha- and beta-aspartyl and alpha- and gamma-glutamyl underivatized peptides. The method is based upon differences in loss of CO from aspartyl or glutamyl B-fragment ions (IB) in these isomers which are rationalized from the stability of the resultant A-fragment ions (IA). It was observed that the ratio of IB:IA which was used in this determination was dependent upon the collision cell pressure. The higher the collision cell pressure, the larger the difference between the IB:IA ratios for these linkages.
authors.affiliation: Research Laboratories, Ortho Pharmaceutical Corporation, Raritan, New Jersey.
authors.forename: J R
authors.initials: JR
authors.lastname: Lloyd
authors.forename: M L
authors.initials: ML
authors.lastname: Cotter
authors.forename: D
authors.initials: D
authors.lastname: Ohori
authors.forename: D L
authors.initials: DL
authors.lastname: Doyle
mesh_terms: D001224:Aspartic Acid; D005971:Glutamates; D013058:Mass Spectrometry; D010455:Peptides / Q000302:isolation & purification*
chemical_list: D005971:Glutamates; D010455:Peptides; D001224:Aspartic Acid