Targeted Trigger Mass Spectrometry for Low-Abundance Peptide Detection
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Solution Overview
Problem
Current mass spectrometry methods are not sensitive enough to detect low-abundance HLA-associated peptides presented on tumor cells, which are potential targets for cancer therapies, due to their low expression levels, limiting the effectiveness of antibody therapeutics and immunotherapies.
Innovation Solution
A novel 'targeted trigger' mode of mass spectrometry is introduced, where a labeled peptide is added to the sample, allowing the system to toggle between discovery and targeted modes based on peptide detection, increasing sensitivity and enabling the identification and sequencing of low-abundance peptides by extending scan duration when the labeled peptide is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mass spectrometry analysis is used to detect HLA-associated peptides, then the system can identify peptides in the sample, but the sensitivity is insufficient to detect low-abundance peptides expressed at very low levels on tumor cells
Solution Approach 1:
A labeled peptide (intermediary substance) is added to the sample to serve as a trigger. When the labeled peptide is detected by the mass spectrometer, it activates a signal that extends the scan duration for subsequent peptides, thereby enhancing the detection sensitivity for low-abundance HLA-associated peptides that would otherwise go undetected.
Solution Approach 2:
The labeled peptide is introduced into the sample before mass spectrometry analysis to pre-condition the detection system. This preliminary action ensures that when low-abundance peptides are present, the system is primed to extend scan duration and improve sensitivity specifically for peptides of interest, rather than uniformly increasing scan time for all peptides.
2Measurement precision
If the scan duration is extended to improve detection sensitivity, then low-abundance peptides can be detected, but the analysis time increases
Solution Approach 1:
The mass spectrometer operates in periodic cycles, alternating between standard scan duration and extended scan duration. The scan duration is dynamically adjusted based on periodic detection of the labeled peptide trigger, allowing the system to achieve high sensitivity when needed while maintaining faster analysis during periods when extended scanning is not required.
Solution Approach 2:
The scan duration is made dynamic rather than static. The system automatically adjusts the scan duration based on real-time detection of the labeled peptide, extending scan time only when the trigger is present and returning to standard scan duration when it is absent, thereby optimizing both sensitivity and analysis time.
3Measurement precision
If the system processes all peptides with uniform high sensitivity, then detection accuracy improves, but processing speed and productivity decrease
Solution Approach 1:
High detection sensitivity is applied locally and selectively only to peptides associated with the labeled peptide trigger, rather than uniformly to all peptides in the sample. This localized approach maintains high productivity for the majority of peptides while achieving superior detection accuracy for the specific low-abundance peptides of interest.
Solution Approach 2:
The scan duration parameter is dynamically changed based on the presence of the labeled peptide trigger. When the trigger is detected, the system switches to extended scan duration mode for enhanced sensitivity; when absent, it maintains standard scan duration, thereby optimizing the balance between detection accuracy and analysis throughput.
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 significantly enhances the detection of low-copy number peptides, allowing for the identification of novel peptide targets and improving the sensitivity of peptide detection, thereby facilitating the development of more effective cancer therapies and vaccines.
Implementation Method 1
processing the mixed sample with an LC-MS/MS system, comprising: i) processing the mixed sample in discovery mode to detect and identify one or more of the unlabeled isolated peptides and the one or more labeled peptides in the mixed sample
Data Source
AI summary
Systems and methods for determining amino acid sequences of peptides that bind to MHC-I or HLA-I complex or MHC-II or HLA-II complex are provided. One embodiment includes isolating peptides from MHC or HLA class I or class II-peptide complexes and adding one or more known labeled peptides of interest to form a sample containing labeled peptides and unlabeled isolated peptides. The method also includes analyzing the sample with an LC-MS/MS system to obtain sequence data of the peptides, and increasing the sensitivity of the LC-MS/MS system when the labeled peptide is detected by the LC-MS/MS system. The method then concludes with determining the amino acid sequence of the unlabeled peptides in an m/z range that includes the m/z of the labeled peptide. The system can be triggered to increase the sensitivity in or near the m/z of the labeled peptide using an algorithm or computer program.