Polypeptide Quantification via LC-MS/MS Without Reference Standards
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Solution Overview
Problem
Current methods for detecting and quantifying polypeptides in plants, such as ELISAs and mass spectrometry, require reference standards and are time-consuming and resource-intensive, making them unsuitable for multiplexed analysis of genetically engineered crops with stacked traits.
Innovation Solution
A method using information-dependent acquisition (IDA) with liquid chromatography-tandem mass spectrometry (LC-MS/MS) that detects tryptic peptides derived from polypeptides without reference standards by comparing chromatograms from sample and negative control plants, allowing for the identification and relative quantification of polypeptides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference standards are used for polypeptide detection and quantification, then measurement precision is improved, but device complexity and loss of substance increase due to the need for additional standards and calibration procedures
Solution Approach 1:
The patent employs stable isotope-labeled polypeptides that are endogenously expressed in the plant system itself, eliminating the need for external reference standards. The system serves its own quantification needs by using naturally occurring or genetically introduced labeled forms of the target polypeptide as internal references, thereby reducing assay complexity while maintaining precision.
Solution Approach 2:
The stable isotope-labeled polypeptides serve multiple functions simultaneously: they act as both the target analyte and the internal reference standard for quantification. This multi-functionality eliminates the need for separate reference standard preparations and enables multiplexed analysis of multiple polypeptides in a single assay.
2Measurement precision
If reference standards are used for polypeptide detection, then measurement precision is improved, but loss of time and loss of substance increase due to additional preparation and calibration steps
Solution Approach 1:
The system uses stable isotope-labeled polypeptides that are either endogenously present or can be introduced via genetic transformation, eliminating the need for separate reference standard synthesis and validation processes. This self-service approach dramatically reduces assay development time from 10-20 months to a much shorter period.
Solution Approach 2:
The stable isotope labels are incorporated into the polypeptide sequence during genetic transformation, preparing the reference functionality in advance. This preliminary action ensures that reference standards are already present in the plant system before analysis, eliminating the need for post-hoc standard preparation and calibration.
3Measurement precision
If multiple separate assays are used for each polypeptide, then measurement precision for individual polypeptides is improved, but productivity decreases due to the need for multiple separate analyses
Solution Approach 1:
The mass spectrometry-based assay with stable isotope-labeled polypeptides provides a universal platform that can simultaneously detect and quantify multiple different polypeptides in a single analysis. Each polypeptide is identified by its unique mass spectrum and retention time, allowing multiplexed analysis without sacrificing individual detection precision.
Solution Approach 2:
The patent merges multiple individual polypeptide detection assays into a single comprehensive mass spectrometry analysis. By combining the detection of multiple stable isotope-labeled polypeptides in one run, the system achieves both high precision for individual targets and high productivity through multiplexing.
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
Enables sensitive and specific detection of polypeptides directly from crude plant extracts without the need for cleanup or enrichment, facilitating the analysis of multiple polypeptides simultaneously and supporting breeding programs by identifying plants with higher expression levels.
Implementation Method 1
liquid chromatography-tandem mass spectrometry (LC-MS/MS)
Implementation Method 2
tandem mass spectrometry (LC-MS/MS)
Data Source
AI summary
A method is provided for detecting a polypeptide of interest in a plant without the use of a reference standard. The method comprises the steps of obtaining a plant expressing the polypeptide of interest and a negative control plant that does not express the polypeptide of interest, and analyzing a sample from each in an information-dependent acquisition (IDA) method. A method is also provided for determining the relative expression level of a polypeptide of interest in a plurality of plants without the use of a reference standard. This method comprises the steps of obtaining a plurality of plants expressing the polypeptide of interest and a negative control plant that does not express the polypeptide of interest, analyzing samples from each in an IDA method, and determining the relative expression level of the polypeptide in each of the plurality of plants.