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Enhanced Ionization of Phosphopeptide Using Ammonium Phosphate as Matrix Additive by MALDI‐MS
Author(s) -
ZHANG Ying,
LU HaoJie,
YANG PengYuan
Publication year - 2008
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.200890336
Subject(s) - phosphopeptide , chemistry , dibasic acid , phosphate , mass spectrometry , monobasic acid , ammonium , ammonium phosphate , electrospray ionization , ionization , chromatography , matrix assisted laser desorption/ionization , inorganic chemistry , ion , desorption , organic chemistry , adsorption , biochemistry , peptide , fertilizer
A new method based upon adding ammonium phosphate as a matrix additive to enhance the ionization efficiency of phosphopeptide in matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) was described. Furthermore, influences of different phosphate salts at various concentrations on the ionization efficiency of phosphopeptide were investigated systematically, finding that the signal intensity for phosphopeptide 48FQ[pS]EEQQQTEDELQDK63 digested from β ‐casein were 5 to 8 times increased in an optimized condition with 10 mmol/L ammonium monobasic phosphate or 3 to 4 times increased with 10 mmol/L ammonium dibasic phosphate as additive to matrix 2,5‐dihydroxybenzoic acid, respectively. Compared with the most optimized matrix system that was currently reported for special ionization of phosphopeptides, the signal intensity of this phosphopeptide was also enhanced by twice when introducing 5 mmol/L ammonium dibasic phosphate into matrix 2,4,6‐trihydroxyacetophenone. In addition, the mechanism was also discussed, assuming that the cooperation function of ammonium cation and phosphate anion was of great importance in enhancing the ionization efficiency of phosphopeptide in MALDI‐MS.