Phosphorylation Analysis by MALDI-TOF MS (2) Phosphopeptide Sequence Analysis Using Seamless PSD

Introduction

Recently, mass spectrometry is being applied to the analysis of phosphopeptide and phosphorylation sites in proteins. Phosphorylation sites are determined using various types of MS/MS (techniques used for detecting fragment ions derived from ions of interest). In almost all cases, however, the instrument configuration used has been based on electrospray ionization (ESI). Here we introduce the phosphorylation site analysis technique based on seamless PSD (sPSD) by MALDI. In the CID method (Collision-Induced Dissociation) used in MALDI-MS/MS amino acid sequence analysis, phosphorylation site information is difficult to obtain due to the marked desorption of the fragile phosphate group caused by collision with the inert gas. However, when sPSD is used in the analysis, the obtained spectra clearly indicate some degree of suppressed phosphate desorption, which is attributed to the absence of inert gas.

July 8, 2009 GMT