title: Negative-ion electrospray ionization tandem mass spectrometry of N-phosphoryl amino acids and dipeptides.
abstract: The negative-ions of N-phosphoryl amino acids were studied by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The negative-ion ESI-MS/MS of N-phosphoryl amino acids showed characteristic fragmentation patterns different from those observed in the corresponding positive-ion ESI-MS/MS and negative-ion fast-atom bombardment mass spectra. For negative-ion ESI-MS/MS, a unique fragmentation from the N-terminal of N-phosphoryl amino acids or peptides containing a free beta-OH or CO(2)H group was observed to yield the characteristic fragment ion (RO)(2)P(O)O(-). The ease of the rearrangement depended on the position of the hydroxyl group in amino acids or peptides, and the N --> O rearrangement mechanism was proposed to involve the participation of the hydroxyl group. From previous solution-phase experiments and theoretical calculations, it was found that the beta-OH group was more active than gamma-OH, and the corresponding difference in negative-ion ESI-MS/MS was consistent with those previous findings.
authors.affiliation: Bioorganic Phosphorus Chemistry Laboratory, Department of Chemistry, School of Life Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
authors.forename: Zhong-Zhou
authors.initials: ZZ
authors.lastname: Chen
authors.forename: Shui-Bing
authors.initials: SB
authors.lastname: Chen
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.forename: Yan-Mei
authors.initials: YM
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Yu-Fen
authors.initials: YF
authors.lastname: Zhao
mesh_terms: D004151:Dipeptides / Q000032:analysis*; D006900:Hydroxylation; D019606:Phosphoamino Acids / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D004151:Dipeptides; D019606:Phosphoamino Acids