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Highly selective and rapid enrichment of phosphorylated peptides using gallium oxide‐coated magnetic microspheres for MALDI‐TOF‐MS and nano‐LC‐ESI‐MS/MS/MS analysis
Author(s) -
Li Yan,
Lin Huaqing,
Deng Chunhui,
Yang Pengyuan,
Zhang Xiangmin
Publication year - 2008
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.200700454
Subject(s) - phosphopeptide , chromatography , chemistry , casein , microsphere , oxide , electrospray , mass spectrometry , gallium , nuclear chemistry , peptide , chemical engineering , organic chemistry , biochemistry , engineering
In this work, we present, to our knowledge, the first demonstration of the utility of iron oxide magnetic microspheres coated with gallium oxide for the highly selective enrichment of phosphopeptide prior to mass spectrometric analysis. These microspheres that we prepared not only have a shell of gallium oxide, giving them a high‐trapping capacity for the phosphopeptides, but also their magnetic property enables easy isolation by positioning an external magnetic field. Tryptic digest products of phosphoproteins including β‐casein, ovalbumin, casein, as well as five protein mixtures were used as the samples to exemplify the feasibility of this approach. In very short time (only 0.5 min), phosphopeptides sufficient for characterization by MALDI‐TOF‐MS were selectively enriched by the Ga 2 O 3 ‐coated Fe 3 O 4 microspheres. The performance of the Ga 2 O 3 ‐coated Fe 3 O 4 microspheres were further compared with Fe 3+ ‐immobilized magnetic silica microspheres, commercial Fe 3+ ‐IMAC resin, and TiO 2 beads for enrichment of peptides originating from tryptic digestion of β‐casein and BSA with a molar ratio of 1:50, and the results proved a stronger selective ability of Ga 2 O 3 ‐coated Fe 3 O 4 microspheres over the other materials. Finally, the Ga 2 O 3 ‐coated Fe 3 O 4 microspheres were successfully utilized for enrichment of phosphopeptides from digestion products of rat liver extract. All results show that Ga 2 O 3 ‐coated Fe 3 O 4 microsphere is an effective material for selective isolation and concentration of phosphopeptides.