Phosphopeptides

The study of phosphorylation and phosphoproteins is important in signal transduction in eukaryotic cells.  Identifying the site of phosphorylation in phosphopeptides has been effectively accomplished using AP/MALDI.

Typical Spectra:

AP/MALDI-MS and MS/MS spectra of a phosphopeptide M.W. 748 Da (Sequence: Ac-Ile-Tyr(PO3H2)-Gly-Glu-Phe-NH2-(ammonium salt)

AP/MALDI spectra of Beta-Casein using Immobilized Metal Affinity Chromatography Ga (III) IMAC: Positive ion MS/MS of base peak 2062.9 Da shows loss of phosphate (-98 Da)

AP/MALDI spectra of Beta-Casein using Immobilized Metal Affinity Chromatography Ga (III) IMAC: Negative ion MS/MS of base peak 2061.4 Da shows loss of phosphate (-98 Da)

Relevant References:

Applications of AP-MALDI Ion Trap Mass Spectrometry for the Analysis of Phosphopeptides
NI Taranenko, VM Doroshenko , AK Shukla, MM Shukla
American Laboratory. 2004; May: 34-38.

Fragmentation of cationized phosphotyrosine containing peptides by atmospheric pressure MALDI/ion trap mass spectrometry 
SC Moyer, CE VonSeggern, RJ Cotter
J. Am. Soc. Mass Spectrom. 2003; 14: 581-592.

Fragmentation of Phosphopeptides by Atmospheric Pressure MALDI and ESI/Ion Trap Mass Spectrometry
SC Moyer, RJ Cotter, AS Woods
J. Am. Soc. Mass Spectrom.  2002; 13: 274-283.

Identification of Tyrosine Sulfation in Conus pennaceus Conotoxins z-PnIA and a-PnIB: Further Investigation of Labile Sulfo- and Phosphopeptides by Electrospray, Matrix-assisted Laser Desorption/Ionization (MALDI) and Atmospheric Pressure MALDI Mass Spectrometry
J-L Wolfender, F Chu, H Ball, F Wolfender, M Fainzilber , MA Baldwin , AL Burlingame
J. Mass Spectrom. 1999; 34; 447-454.

Using AP MALDI for Phosphopeptide Mining on an LCQ Deca XP+ Ion Trap Mass Spectrometer
SM Peterman, JJ Mulholland
ASMS 2003; TPM 228.

Negative and Positive AP-MALDI Analysis of Synthetic Phosphopeptides and Bovine Beta-Casein using Immobilized Metal Affinity Chromatography Ga(III) IMAC
NI Taranenko, AV Pashkova, VM Doroshenko
ASMS 2003; WPP 269.