Use of polyethylenimine-modified magnetic nanoparticles for highly specific enrichment of phosphopeptides for mass spectrometric analysis.
Phosphopeptides have been isolated and concentrated by use of polyethyleneimine (PEI)-modified magnetic nanoparticles as an extremely specific affinity probe. The particles specifically captured phosphopeptides from a tryptic digest of a protein mixture that contained 0.07% (mole/mole) phosphoproteins, which is the highest specificity obtained to date. The time required for enrichment of the phosphopeptides was 1 min only. PEI-modified magnetic nanoparticles carry positive charges over a wide range of pH-between 3 and 11. This feature means the particles are effectively dispersed in solution during phosphopeptide capture. Mass spectrometric analysis revealed the very high efficiency of enrichment of phosphopeptides that contain both single and multiply-phosphorylated sites. The detection limit in the analysis of phosphopeptides obtained from both bovine α-casein and β-casein by matrix-assisted laser desorption/ionization mass spectrometry was 5 fmol. This approach was also used to enrich the phosphopeptides in a protein digest obtained from non-fat milk.
Department of Chemistry, National Dong Hwa University, Taiwan, ROC.
Cheng-Tung
CT
Chen
Lee-Yih
LY
Wang
Yen-Peng
YP
Ho
D000327:Adsorption; D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000737:chemistry; D002417:Cattle; D008969:Molecular Sequence Data; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification*; D011094:Polyethyleneimine / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D002364:Caseins; D010748:Phosphopeptides; D011094:Polyethyleneimine