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Updated: May 31, 2026
11:53
Quantitative Proteomics Using Reductive Dimethylation for Stable Isotope Labeling
Published on: July 1, 2014
Isotope Decluttering Reduces Spectral Complexity while Maintaining Protein Structure
Sneha S Hakke1, Willem E M Noteborn2, Birol Cabukusta1
1Maastricht Multi-Modal Molecular Imaging Institute (M4i), Maastricht University, 6229 ER Maastricht, The Netherlands.
Analytical Chemistry
|May 29, 2026
Summary
Isotope depletion simplifies mass spectrometry (MS) analysis of large proteins and complexes by reducing isotopic complexity. This method enhances signal-to-noise ratio for accurate mass measurement and maintains structural integrity for detailed analysis.
Area of Science:
- Biochemistry
- Analytical Chemistry
- Structural Biology
Background:
- Accurate mass determination is crucial in mass spectrometry (MS) for molecular identification.
- Heavier isotopes increase spectral complexity and reduce signal-to-noise ratio (SNR), especially for large proteins and complexes.
- Current methods struggle with spectral complexity in large biomolecules.
Purpose of the Study:
- To investigate the impact of isotope depletion on mass spectrometry analysis of large protein complexes.
- To assess the structural integrity of isotope-depleted proteins and complexes.
- To evaluate isotope depletion as a method for improving MS-based protein identification.
Main Methods:
- Expression and purification of *Mycobacterium tuberculosis* protein complexes (EsxAB and BfrB) under isotope-depleted conditions.
- Application of isotope depletion to bacterioferritin B (BfrB), the largest reported complex analyzed under native conditions.
- Analysis of structural integrity using single-particle cryo-electron microscopy (cryo-EM).
Main Results:
- Isotope-depleted proteins and complexes exhibited simplified mass spectra with reduced isotopic distribution.
- Significant increase in the SNR of the monoisotopic peak was observed.
- Improved protein sequence coverage was achieved using native top-down MS.
- Cryo-EM confirmed that isotope depletion preserves protein structural integrity at atomic resolution.
Conclusions:
- Isotope depletion effectively simplifies mass spectra and enhances SNR for large proteins and complexes.
- This technique improves accuracy in mass measurement and protein identification via MS.
- Isotope depletion is a viable method for high-accuracy MS analysis without compromising protein structure.
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