Picolinamidination of phosphopeptides for MALDI-TOF-TOF mass spectrometric sequencing with enhanced sensitivity.
Two orders of magnitude matrix-assisted laser desorption/ionization (MALDI) signal enhancement of phosphopeptides has been achieved by picolinamidination of N-terminal amine group and epsilon-amine group of lysine residues. Due to the presence of picolinamidination tag at the N-terminal amine of peptides, MS/MS spectra with a strong b-ion series was obtained, which greatly facilitated sequencing and identification of the phosphorylation site. Phosphorylation site of a phosphopeptide could be identified from MALDI TOF/TOF spectrum obtained from a tryptic or a chymotryptic phosphopeptide, which was not even detected in the positive ion mode, without signal enhancement by picolinamidination, due to the negative charge of the phosphate group in the presence of other peptides.
Kim
Jong-Seo
JS
Department of Chemistry, Seoul National University, Seoul, Korea.
Cui
Enshi
E
Kim
Hie-Joon
HJ
D000577:Amides / Q000737:chemistry*; D008832:Microchemistry / Q000379:methods*; D010449:Peptide Mapping / Q000379:methods*; D010748:Phosphopeptides / Q000737:chemistry*; D020539:Sequence Analysis, Protein / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
D000577:Amides; D010748:Phosphopeptides