Targeted MS-3 Peptide Quantification via Y-Ion Segmentation
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Solution Overview
Problem
Conventional MS-3 analysis lacks sensitivity for targeted peptide quantification, requiring large dwell times and prior knowledge of fragmentation behavior, limiting its application in multiplexed analyses of hundreds or thousands of peptides.
Innovation Solution
A general-purpose targeted MS-3 method is developed, isolating and fragmenting y-type first-generation fragment ions with m/z values greater than the precursor, generating second-generation y-type fragment ions with m/z values less than the precursor, and using these for quantification, allowing for qualitative and quantitative analysis without prior knowledge of fragmentation behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MS-3 analysis is used for targeted peptide quantification, then structural information can be obtained through multiple fragmentation stages, but sensitivity is insufficient and large dwell times are required
Solution Approach 1:
The patent segments the fragmentation process into two distinct stages: first generating y-type ions through initial fragmentation, then selectively fragmenting only those y-type ions in a second stage. This segmentation allows the method to focus computational and analytical resources on the most informative fragment ions, thereby improving sensitivity while reducing the time required compared to conventional MS-3 analysis that processes all fragment ions equally
Solution Approach 2:
The method performs preliminary identification and selection of y-type ions before the second fragmentation stage. By pre-identifying which fragment ions are of interest (those with m/z greater than the precursor) and preparing them for selective further fragmentation, the system optimizes the subsequent analysis step, improving overall sensitivity while minimizing the dwell time required for the critical second fragmentation and detection phase
2Adaptability or versatility
If conventional MS-3 analysis is applied to multiplexed analyses of hundreds or thousands of peptides, then comprehensive peptide identification can be achieved, but the analysis efficiency is limited due to required prior knowledge of fragmentation behavior
Solution Approach 1:
The patent develops a universal MS-3 method that applies to all peptides regardless of their specific fragmentation behavior. By focusing on y-type ions (which are consistently produced across different peptides) and using their characteristic m/z relationships with precursors, the method creates a general-purpose approach that can be applied to multiplexed analyses of hundreds or thousands of peptides without requiring peptide-specific optimization, thereby improving both adaptability and productivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances sensitivity and selectivity in peptide analysis, reducing dwell times and enabling efficient multiplexed MS-3 analysis of peptides, even when specific fragmentation data is not available.
Implementation Method 1
selecting single mass-to-charge (m/z) values and subjecting the precursor ions to fragmentation
Implementation Method 2
subject the precursor ion to energetic collisions with a neutral gas so as to analyze the mass of the resulting fragment ions
Implementation Method 3
the collision cell may be operated as an ion trap, wherein fragment ions are resonantly excited to promote further CID
Data Source
AI summary
A method comprises: obtaining a precursor mass-to-charge value, (m/z)p, of a target precursor ion having formula [M+2A]2+, M being a peptide molecule and A being one or more adducts; generating ions from a sample by an ion source; purifying and fragmenting ions comprising the (m/z)p, thereby generating a plurality of MS-2 species; co-purifying and co-fragmenting a selected subset of the MS-2 species, thereby generating a plurality MS-3 species, wherein each selected MS-2 species is a y-type ion species comprising a respective (m/z)f that is greater than (m/z)p; mass analyzing the MS-3 species and selecting a subset thereof, each selected MS-3 species comprising a respective (m/z)g that satisfies a mass-to-charge selection criterion; and determining a quantity of the peptide from a summation of mass spectral intensities corresponding to the selected MS-3 species.