Sequencing of Phosphopeptide using Post-Decay Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

Abstract

A simple method of solid-phase derivatization and sequencing of phosphopeptide has been developed for rapid using post-decay (PSD) matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The phosphopeptide are chemically modified by 4-sulfophenyl isothiocyanate. The derivatization traction introduces a negative sulfonic acid group at the N-terminus of a phosphopeptide, which can increase the efficiency of post-decay fragmentation and enable the selective detection of only a single series of fragment ions (y-ions). In this study, we applied this approach to screen Cx31 phosphorylation sites using HT1080 cells stable expressing a myctagged Cx31. Serine 234 of the Cx31 was determined to be a site of phosphorylation.