Fluorescent modification for peptide sequencing by postsource decay-matrix assisted laser desorption/ionization-mass...

Area of Science:

• Biochemistry
• Analytical Chemistry
• Molecular Biology

Background:

• Peptide sequencing is crucial for understanding protein function, particularly in viral proteins like those in influenza.
• Matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) is a powerful tool for peptide analysis.
• Postsource decay (PSD) fragmentation in MALDI-MS can be challenging for complete peptide sequence interpretation due to low ion observation.

Purpose of the Study:

• To investigate a method for improving peptide sequence analysis using MALDI-TOF-MS.
• To enhance the sensitivity and interpretability of postsource decay (PSD) fragment spectra for peptides.
• To demonstrate the utility of fluorescent modification for comprehensive peptide sequencing.

Main Methods:

• Sequential analysis of a peptide (CDYEGRLI) related to influenza virus nucleic proteins.
• Application of postsource decay (PSD) fragmentation with matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS).
• Modification of the peptide using a 4(5)-(iodoacetamide) fluorescent reagent to improve fragmentation analysis.

Main Results:

• Standard MALDI-TOF-MS with PSD fragmentation yielded insufficient fragment ions for complete sequence interpretation.
• Fluorescent modification of the peptide significantly improved the sensitivity of the MALDI-PSD fragment spectrum.
• Nearly all sequential b-series fragment ions were clearly observed in the modified peptide's spectrum, allowing for complete sequence determination.

Conclusions:

• Fluorescent modification is advantageous for the total sequencing of peptides by MALDI-MS.
• This method enhances the reliability and completeness of peptide sequence analysis.
• The findings support the use of fluorescent labeling to overcome limitations in MALDI-TOF-MS peptide sequencing.