Pseudo-Electropherogram Reconstruction for Protein PTM Analysis
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Solution Overview
Problem
Current protein mass spectrometry techniques struggle to accurately analyze protein heterogeneity due to post-translational modifications (PTMs) and protein aggregates, especially in complex mixtures, limiting the identification of labile PTMs and protein sequence coverage.
Innovation Solution
The method involves reconstructing a pseudo intact mass spectrum from peptide-level mass spectrometry data, allowing users to select and exclude modification groups, and comparing it with experimentally derived data to identify PTMs and protein aggregates, using software to generate theoretical distributions and overlays for enhanced analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If intact protein mass spectrometry is used to capture protein heterogeneity and detect degradation products, then the ability to identify PTMs and degradation products is improved, but measurement precision deteriorates in complex protein mixtures
Solution Approach 1:
The patent applies segmentation by dividing the intact protein into peptide fragments through proteolytic digestion. This allows the complex protein to be analyzed as smaller, more manageable peptide components that can be individually identified with high precision using bottom-up mass spectrometry, while still enabling inference of the overall protein structure and heterogeneity characteristics.
2Measurement precision
If bottom-up peptide-level analysis is used to achieve high accuracy protein identification, then measurement precision is improved, but the ability to identify labile PTMs and capture protein heterogeneity deteriorates
Solution Approach 1:
The patent uses peptide sequence coverage as an intermediary to bridge bottom-up and top-down approaches. By achieving high-confidence peptide identifications through bottom-up analysis and using these to constrain and inform intact protein analysis, the method transfers the precision advantages of peptide-level analysis to the protein-level heterogeneity and PTM detection capabilities of intact analysis.
3Adaptability or versatility
If intact protein analysis is used to detect degradation products and PTMs, then adaptability is improved, but device complexity increases due to requirements for ion trapping mass spectrometers and multiple ion selection steps
Solution Approach 1:
The patent extracts the complex ion trapping and multiple selection steps from the analysis workflow by using simpler bottom-up mass spectrometry for peptide identification. The method takes out the need for complex intact protein manipulation while retaining the ability to detect PTMs and degradation products through peptide-level analysis and computational reconstruction of protein characteristics.
Data Source
AI summary
Methods and apparatuses for the identification and/or characterization of properties of a macromolecule based on mass spectrometry data. Specifically, described herein are methods and apparatuses for converting peptide-level data into a pseudo-intact mass spectra. Also described herein are methods and apparatuses for converting peptide-level data into a pseudo-electropherogram. The methods may be well suited for analyzing proteins and protein complexes, including estimating properties of post-translational modifications of the proteins and protein complexes. Methods may include generating a theoretical graph or spectrum based on peptide-level mass spectrometry data. In some embodiments, the theoretical graph may be a theoretical intact mass spectrum or a theoretical charge distribution spectrum.