Spatial Proteomics by Parallel Accumulation-Serial Fragmentation Supported MALDI MS/MS Imaging: A First Glance Into...

Area of Science:

• Proteomics
• Mass Spectrometry Imaging

Background:

• Matrix-assisted laser desorption/ionization (MALDI) imaging offers rapid, cost-effective peptide measurements in spatial proteomics.
• In situ peptide identification remains a significant challenge in MALDI imaging.

Purpose of the Study:

• To integrate trapped ion mobility spectrometry (TIMS)-based parallel accumulation-serial fragmentation (PASEF) into MALDI imaging.
• To enable multiplexed MS/MS imaging for enhanced peptide identification.

Main Methods:

• Performed MALDI TIMS MS1 survey measurements.
• Generated precursor lists with mass over charge and ion mobility values.
• Utilized a dual TIMS system for precursor trapping, elution, and analysis in a quadrupole time-of-flight device.
• Enabled multiplexed MALDI MS/MS imaging and identified precursors via peptide-to-spectrum matching.

Main Results:

• Presented the first multiplexed MALDI TIMS MS/MS imaging (iprm-PASEF) of tryptic peptides.
• Demonstrated applicability on two distinct tissue specimens in four-plex and five-plex setups.
• Successfully identified precursors using MASCOT and corroborated findings with LC-MS/MS and fragment colocalization analyses.

Conclusions:

• Introduced a novel pipeline (iprm-PASEF) for multiplexed, spatial identification of tryptic peptides in MALDI imaging.
• This represents a significant advancement towards integrating MALDI imaging into spatial proteomics.