Distinct classes of multi-subunit heterogeneity: analysis using Fourier Transform methods and native mass
1Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, OR 97403-1253, USA. jprell@uoregon.edu.
The Analyst
|May 28, 2020
Summary
This study introduces a new Fourier Transform (FT)-based method to analyze complex biological mixtures using mass spectrometry. The approach effectively differentiates and quantifies heterogeneity in multi-subunit protein complexes and lipid assemblies.
Area of Science:
- Biophysical Chemistry
- Analytical Chemistry
- Biochemistry
Background:
- Native electrospray mass spectrometry (native MS) is crucial for determining the stoichiometry of polydisperse biological complexes.
- Analyzing subunit stoichiometry in complexes with multiple different subunits is challenging due to overlapping mass-to-charge (m/z) distributions.
- Existing Fourier Transform (FT)-based methods can determine lipid composition but struggle with detailed statistical analysis of mixed-subunit populations.
Purpose of the Study:
- To develop a theoretical framework for analyzing common classes of heterogeneity in mixed-subunit analytes.
- To demonstrate the application of FT-based mass spectrometry methods for differentiating and analyzing these complex mixtures.
- To provide a robust classification scheme for studying analyte heterogeneity in mass spectrometry.
Main Methods:
- Theoretical description of three classes of heterogeneity: superpositions, convolutions, and multinomial distributions.
- Application of FT-based analysis to model datasets representing these distributions.
- Validation using real biological samples: mixed-lipid Nanodiscs, copolymers, and ubiquitin isotope distributions.
Main Results:
- Successfully differentiated and analyzed mass spectra corresponding to superposition, convolution, and multinomial distributions.
- Demonstrated the practical application of the FT method to real-world biological samples, including protein-lipid Nanodiscs and ubiquitin.
- Established a classification scheme for analyzing heterogeneity in mixed-subunit analytes.
Conclusions:
- The presented FT-based method and classification scheme offer a powerful approach for analyzing complex, heterogeneous biological assemblies.
- This methodology enhances the capability of mass spectrometry to determine subunit stoichiometry and composition in polydisperse systems.
- The findings are broadly applicable to mass spectrometry and other techniques dealing with overlapping periodic signals from analyte mixtures.
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