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Statistical Framework for Identifying Differences in Similar Mass Spectra: Expanding Possibilities for Isomer
Hoi-Ting Wu1, Dylan L Riggs1, Yana A Lyon1
1Department of Chemistry, University of California, Riverside, California 92521, United States.
Analytical Chemistry
|May 2, 2023
Summary
This study introduces a novel framework for comparing mass spectra based on peak intensity differences, enabling confident identification of peptide isomers. The method accurately distinguishes between similar molecules, even when fragmentation patterns lack unique mass-to-charge ratios.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Spectrometry
Background:
- Isomeric molecules present significant analytical challenges due to their structural similarity.
- Traditional mass spectrometry (MS) and tandem-MS often yield similar fragmentation patterns for isomers, hindering differentiation.
- Subtle differences in peak intensities within mass spectra can contain valuable information for isomer identification.
Purpose of the Study:
- To develop a statistical framework for comparing mass spectra based on peak intensity variations.
- To enable confident identification and characterization of peptide isomers using this novel approach.
- To demonstrate the utility of the method across various dissociation techniques and instrumental settings.
Main Methods:
- A framework was developed to compare mass spectra by analyzing differences in peak intensities.
- Statistical probabilities were calculated to determine if spectra originate from distinct analytes.
- The method was validated using various peptide isomers, including d/l amino acid substitutions and Leu/Ile.
Main Results:
- The framework successfully identified various peptide isomers, including those with subtle structural differences.
- The method proved robust across different tandem-MS dissociation techniques (CID, HCD, ETD, RDD).
- Quantification of isomeric mixtures was achieved with highly linear and reproducible calibration curves.
Conclusions:
- This intensity-based spectral comparison framework provides a reliable method for isomer identification.
- The approach is adaptable to diverse instrumental parameters and data acquisition methods (direct infusion, LC-MS).
- The developed framework has broad applicability beyond isomer characterization to other analyses involving similar mass spectra.
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