Peptide Fragmentation and Surface Structural Analysis by Means of ToF-SIMS Using Large Cluster Ion Sources

Area of Science:

• Surface analysis
• Biophysics
• Analytical chemistry

Background:

• Accurate peptide and protein structural analysis is essential for biochip and biodevice development.
• A high-resolution technique for direct surface analysis of biomolecules is needed.

Purpose of the Study:

• Evaluate Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) for direct protein and peptide analysis on surfaces.
• Determine optimal conditions for peptide structural analysis using ToF-SIMS.

Main Methods:

• Utilized low-energy argon cluster ion beams for peptide and protein analysis.
• Investigated peptide fragmentation patterns dependent on primary ion beam energy.
• Analyzed ToF-SIMS specific fragment ions.

Main Results:

• ToF-SIMS with cluster ion beams provides partial structural information for peptides and proteins.
• Optimal energy range for peptide analysis using fragments and [M + H] ions is approximately 6–10 eV/atom.
• Extremely low energies (≤ 4 eV/atom) lead to side-chain moiety cleavage.

Conclusions:

• ToF-SIMS, particularly with cluster ion beams, is effective for analyzing peptide and protein structures on surfaces.
• Specific energy ranges are crucial for obtaining relevant structural information and avoiding excessive fragmentation.
• This technique offers complementary fragmentation data compared to conventional MS/MS.