Parallel VEGF-A Splice Variant Quantification via Mass Spectrometry
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Solution Overview
Problem
Current methods for quantifying protein variants, such as ELISA, face challenges including the need for specific antibodies, high costs, time-consuming processes, and inability to simultaneously measure multiple variants, leading to inaccurate reflection of medicinal effects in cancer treatment.
Innovation Solution
A method using mass spectrometry for parallel quantification of protein variants, involving protease digestion and detection of specific peptides, allows for simultaneous analysis of multiple variants without separating them, applicable to proteins like VEGF-A, enabling accurate measurement of individual variants in a sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ELISA is used to quantify protein variants, then specific antibodies can be used for detection, but the cost increases and multiple variants cannot be measured simultaneously
Solution Approach 1:
The patent replaces the antibody-based immunological detection system (ELISA) with a mass spectrometry-based detection system. This substitution eliminates the need for multiple specific antibodies for different variants, as mass spectrometry can distinguish variants based on their mass-to-charge ratio differences arising from alternative splicing, thereby reducing system complexity while maintaining measurement precision
Solution Approach 2:
The mass spectrometry system serves as a universal detection platform that can simultaneously quantify multiple protein variants (VEGF-A121, VEGF-A145, VEGF-A165, VEGF-A189, and their b-variants) using a single detection method, whereas ELISA requires separate antibody pairs for each variant, demonstrating multi-functionality that reduces the number of required reagents and simplifies the overall system
2Measurement precision
If ELISA is used to quantify protein variants, then detection can be performed, but the process becomes time-consuming
Solution Approach 1:
The patent combines the quantification of multiple protein variants into a single mass spectrometry run, where all variants are detected and quantified simultaneously based on their unique mass spectra. This merging of multiple detection tasks into one unified process dramatically reduces the total measurement time compared to performing separate ELISA assays for each variant while maintaining accurate detection
Solution Approach 2:
The patent employs preliminary proteolytic digestion of the protein samples into peptides before mass spectrometry analysis. This preliminary action breaks down the large protein molecules into smaller peptides that can be rapidly analyzed by mass spectrometry, significantly reducing the analysis time while preserving the variant-specific information needed for accurate quantification
3Ease of operation
If total VEGF-A amount is measured, then quantification is simplified, but the reflection of medicinal effects becomes inaccurate
Solution Approach 1:
The patent segments the total VEGF-A measurement into individual quantification of each splicing variant (VEGF-A121, VEGF-A145, VEGF-A165, VEGF-A189, and their b-variants). By measuring each variant separately using mass spectrometry, the method maintains quantification simplicity through automated analysis while accurately reflecting medicinal effects, as different variants have different biological activities that are lost in total amount measurements
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 provides accurate and efficient quantification of protein variants, enabling personalized cancer treatment strategies by distinguishing between angiogenesis-promoting and inhibiting effects, thus optimizing chemotherapy and radiotherapy approaches.
Implementation Method 1
detection using mass spectrometry of a peptide obtained by protease digestion of the protein
Implementation Method 2
protease digestion and detection of specific peptides
Data Source
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AI summary
There are numerous proteins having different in vivo effects depending on variants. In order to gain a more accurate understanding of an in vivo effect of a protein, when the protein in a sample is quantified, it is necessary to measure an amount of each variant that can be present. Provided is a method for performing parallel quantification of variants of a protein having 2 or more variants using mass spectrometry. The method includes: protease-digesting a protein in a sample; detecting, using mass spectrometry, among peptides obtained by the protease digestion, peptides having amino acid sequences specific to the variants without separating the peptides; and determining amounts of the variants in the sample based on results of the detection.