title: Comparison of the positive and negative ion electrospray mass spectra of some small peptides containing pyroglutamate.
abstract: The positive ion electrospray mass spectra of [M+H](+) and the negative ion electrospray mass spectra of [M-H](-) ions of selected pyroglutamate containing peptides both provide sequencing data. The negative ion spectra show the normal alpha and beta backbone cleavages in addition to delta and gamma backbone cleavages initiated by the side chains of Glu and Phe residues. For example, the [M-H](-) ion of pGlu Pro Gln Val Phe Val-NH(2) shows delta and gamma peaks at m/z 224 (delta, Gln3), 244 (gamma, Phe4), 451 (delta, Phe4), 471 (gamma, Gln3). Some of the negative ion spectra show unusual grandaughter peaks that originate by alpha and beta, or delta and gamma backbone cleavages of a beta(1) cleavage ion.
authors.affiliation: Department of Chemistry, The University of Adelaide, South Australia 5005.
authors.forename: Pinmanee
authors.initials: P
authors.lastname: Boontheung
authors.forename: Craig S
authors.initials: CS
authors.lastname: Brinkworth
authors.forename: John H
authors.initials: JH
authors.lastname: Bowie
authors.forename: Russell V
authors.initials: RV
authors.lastname: Baudinette
mesh_terms: D000818:Animals; D005260:Female; D007614:Macropodidae / Q000378:metabolism*; D010455:Peptides / Q000032:analysis*; D011761:Pyrrolidonecarboxylic Acid / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D010455:Peptides; D011761:Pyrrolidonecarboxylic Acid