Sequencing Grade Tandem Mass Spectrometry for Top-Down Proteomics Using Hybrid Electron Capture Dissociation Methods...

Area of Science:

• Proteomics
• Analytical Chemistry
• Biochemistry

Background:

• Electron capture dissociation (ECD) offers superior characterization of large peptides and proteins, preserving labile post-translational modifications.
• Traditional ECD is limited to high magnetic field Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS).

Purpose of the Study:

• To demonstrate the use of an electromagnetostatic ECD cell for performing ECD and hybrid ECD methods on a benchtop quadrupole-Orbitrap mass spectrometer.
• To enable facile installation and independent ion manipulation for various fragmentation techniques.

Main Methods:

• An electromagnetostatic ECD cell was designed to replace the transfer octapole in a quadrupole-Orbitrap mass spectrometer.
• Experiments involved Electron Capture Dissociation (ECD), UV photodissociation (ECuvPD), and collisional activation (EChcD) on ubiquitin and carbonic anhydrase II.
• Fragmentation propensities were benchmarked for ECD, ECuvPD, and EChcD.

Main Results:

• ECD provided extensive sequence coverage for ubiquitin and carbonic anhydrase II (29 kDa), indicating pseudo-activated ion conditions.
• High numbers of d- and w-ions facilitated differentiation of isobaric isoleucine and leucine residues.
• Achieved 93% sequence coverage for carbonic anhydrase II using ECD, 95% with ECuvPD, and 91% with EChcD.

Conclusions:

• The electromagnetostatic ECD cell enables comprehensive protein characterization up to 29 kDa on a benchtop instrument.
• This technology expands the accessibility of advanced protein sequencing and characterization methods.
• Demonstrated high sequence coverage for model proteins and monoclonal antibody subunits.