HPPD Peptide Biomarkers for Selective Protein Quantification
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Solution Overview
Problem
Current immunoassays struggle to selectively detect and quantify target proteins in complex biological samples, particularly in crop plants, due to limitations such as cross-reactivity and inability to recognize post-translational modifications, leading to unreliable quantification and differentiation between similar proteins.
Innovation Solution
Development of labeled surrogate peptides and their transition ions for use in mass spectrometry, specifically designed through empirical analysis and in silico digestion, to selectively detect and quantify p-hydroxyphenylpyruvate dioxygenase (HPPD) proteins in crop plants, using stable isotope-labeled amino acids and optimized peptide parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If immunoassays are used for protein detection, then specificity and sensitivity can be achieved, but cross-reactivity with similar proteins and inability to recognize post-translational modifications reduce reliability
Solution Approach 1:
The patent replaces the immunoassay system (antibody-based mechanical recognition) with a mass spectrometry system (physical measurement of peptide mass and sequence). This substitution eliminates cross-reactivity issues inherent in antibody-protein interactions and enables direct detection of specific peptide sequences regardless of post-translational modifications, thereby improving both specificity and reliability of protein quantification.
Solution Approach 2:
The patent changes the detection parameter from antibody binding affinity (qualitative/quantitative signal) to peptide mass-to-charge ratio and sequence composition (physical constants). This parameter change allows precise identification of specific peptide sequences and their modifications, eliminating the cross-reactivity problems of immunoassays and enabling accurate quantification even in complex biological samples.
2Measurement precision
If multiple proteins are analyzed using immunoassays, then separate tests are required for each protein, but this increases time consumption and reduces throughput
Solution Approach 1:
The patent merges the analysis of multiple proteins into a single mass spectrometry run by detecting their respective peptide fragments simultaneously. The mass spectrometer can identify and quantify multiple peptide sequences in one analysis, eliminating the need for separate immunoassays for each protein and dramatically increasing throughput while maintaining precise detection capabilities.
Solution Approach 2:
The mass spectrometry system serves as a universal detection platform that can analyze multiple different proteins and peptide sequences in a single experiment. This multi-functionality allows simultaneous quantification of various target proteins without requiring protein-specific reagents or separate test protocols, thereby improving productivity while preserving measurement precision.
3Reliability
If antibodies are used for protein detection, then detection can be performed, but antibodies require purification steps to enhance sensitivity and reduce background
Solution Approach 1:
The patent substitutes the antibody-based detection system with direct mass spectrometry detection of peptide fragments. This elimination of the antibody component removes the need for antibody purification steps and reduces assay complexity, while maintaining or improving detection reliability through direct physical measurement of peptide sequences without biological reagent variability.
4Measurement precision
If ELISA systems are used for protein quantification, then quantification can be performed, but subtle changes to target proteins such as post-translational modifications are not detected
Solution Approach 1:
The patent replaces ELISA quantification with mass spectrometry-based peptide analysis. This substitution enables detection of subtle protein changes including post-translational modifications because the technique directly measures peptide mass, sequence, and structural characteristics. Any modification to the protein or its peptides is directly observable through mass shift or sequence variation, preserving critical biological information that ELISA cannot detect.
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
The method provides precise and selective detection and quantification of HPPD proteins in complex biological matrices, reducing endogenous background interference and enabling high-throughput analysis across various crop samples.
Implementation Method 1
analyzed by liquid chromatography coupled to a mass spectrometer
Implementation Method 2
The field of MS-based analysis has resulted in an important advancement of targeted protein analysis
Implementation Method 3
resolving the peptide fragment mixture from step g via liquid chromatography
Data Source
AI summary
The invention relates generally to peptide biomarkers with specific ionization characteristics to directly quantify one or more target HPPD proteins in biological samples, including crop plant samples, by liquid chromatography coupled tandem mass spectrometry multiple reaction monitoring (MRM). The peptide biomarkers in combination with MRM-based methods may be used to quantify a single target protein or multiple target proteins within a crop plant, such as maize, utilizing selected peptide biomarkers either alone or in combination. The present disclosure allows for broad based, reliable quantitation in different biological matrices, including plant matrices. Also provided are different peptide biomarker combinations that can be used to perform the methods of the invention.