In-Source Atmospheric Pressure-Electron Capture Dissociation (AP-ECD)

A New Tool for Mass Spectrometric Analysis of Peptides and Proteins

Advantages

  • The device is suitable for coupling to any suitable mass analyzer, and may be retrofit to existing spectrometers. Thereby providing a low-cost option for ECD experiments and characterization of PTMs.
  • Sensitivity compatible with routine proteomic sequencing experiments.

Technology Details

Characterization of both the primary sequence and the post-translational modifications (PTMs) of peptides and proteins are central activities in diverse areas of biomedical research. Due to their lability PTMs are difficult to characterize using standard mass spectrometry fragmentation techniques.  Electron Capture (ECD) and Electron Transfer Dissociation (ETD) have emerged as powerful mass spectroscopic techniques for probing PTMs. Both ECD and ETD are normally performed using sophisticated, late-model ion trapping instruments, which have only recently become commercially available. Hence, the vast majority of the mass spectrometers used for protein/peptide analysis worldwide were not originally designed to perform either ECD or ETD, seriously restricting their utility in the analysis of PTMs.

The technology is a new, practical, in-source atmospheric pressure (AP)-ECD method, that is suitable for use with mass spectrometers not otherwise equipped with ECD or ETD capabilities. The method utilizes a commercial atmospheric pressure photoionization (APPI) source, in conjunction with a novel nebulizer to provide electrospray-like ionization capabilities.  

Example spectra of substance P (10 µM at 500 nl/min) obtained by (a) spray ionization only, and (b) in-source AP-ECD with the PID lamp on are shown below.