Distinction Between Phosphorylated and Sulfated Peptides by Matrix Assisted Laser Desorption Ionization Reflector Mass Spectrometry at the Sub Picomole Level

Abstract

Publisher Summary This chapter describes distinction between phosphorylated and sulfated peptides by matrix-assisted laser desorption ionization (MALDI) reflector mass spectrometry at the sub-picomole level. The reflector MALDI technique can be used for the identification of sulfated and phosphorylated peptides and their distinction in sub-picomole amounts. Metastable ion spectra can be used to localize the modification in the peptide sequence. The nature of the MALDI process permits the performance of several experiments using the same target. This fact allows for the development of sequential diagnostic tests by changing the parameters of the instrument such as measuring in the linear versus the reflector modes. As it uses only sub-picomole amounts of sample, the MALDI technique is the ideal counterpart to Edman sequencing in the structural elucidation of modified peptides. The methods developed might be a part of a MALDI measurement strategy that could be performed with great advantage on a peptide prior to its application to the Edman sequencer.