title: Plasma desorption mass spectrometry of phosphopeptides: an investigation to determine the feasibility of quantifying the degree of phosphorylation.
abstract: The intact ion yields of phosphotyrosine, phosphothreonine and mono- and diphosphoserine residue-containing peptides have been compared with the non-phosphorylated sequences using plasma desorption mass spectrometry. Equimolar mixtures of the phosphorylated (Mp) and non-phosphorylated peptides (M) were also analysed. The positive mass spectra of these mixtures show a higher intensity of the [M + H]+ compared with the [Mp + H]+. In the negative mass spectrum, the bias towards the [M - H]- compared with the [Mp - H]- was reduced, but the spectra generally did not accurately reflect the stoichiometry.
authors.affiliation: University of Uppsala, Biomedical Centre, Sweden.
authors.forename: A G
authors.initials: AG
authors.lastname: Craig
authors.forename: A
authors.initials: A
authors.lastname: Engström
authors.forename: H
authors.initials: H
authors.lastname: Bennich
authors.forename: E
authors.initials: E
authors.lastname: Hoffmann-Posorske
authors.forename: H E
authors.initials: HE
authors.lastname: Meyer
mesh_terms: D000595:Amino Acid Sequence; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000032:analysis; D010748:Phosphopeptides / Q000032:analysis*; D010766:Phosphorylation; D010769:Phosphothreonine / Q000032:analysis; D019000:Phosphotyrosine; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D009842:Oligopeptides; D010748:Phosphopeptides; D010769:Phosphothreonine; D019000:Phosphotyrosine; D014443:Tyrosine; C037642:kemptide