Negative-ion electrospray ionization tandem mass spectrometry of N-phosphoryl amino acids and dipeptides.
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.
Chen
Zhong-Zhou
ZZ
Bioorganic Phosphorus Chemistry Laboratory, Department of Chemistry, School of Life Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
Chen
Shui-Bing
SB
Chen
Yi
Y
Li
Yan-Mei
YM
Chen
Jing
J
Zhao
Yu-Fen
YF
D004151:Dipeptides / Q000032:analysis*; D006900:Hydroxylation; D019606:Phosphoamino Acids / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization; D016339:Spectrometry, Mass, Fast Atom Bombardment
D004151:Dipeptides; D019606:Phosphoamino Acids