IGF-2 Variant Quantitation Using Multi-m/z Mass Spectrometry
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Solution Overview
Problem
Existing high-resolution LC-MS methods fail to accurately quantify insulin-like growth factor 2 (IGF-2) variants due to amino acid substitutions caused by polymorphisms, which alter mass and are not detected by peak intensity at a specific mass-to-charge ratio, leading to incomplete quantitation.
Innovation Solution
A method using high-resolution/high-accuracy mass spectrometry with specific m/z ratios (1089.8±0.5 and 1090.23±0.5) to detect and quantify novel IGF-2 variants, combined with purification techniques like HPLC and SPE, and ionization modes such as electrospray ionization, to identify and measure IGF-2 variants in samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution LC-MS is used to quantify peptides based on peak intensity at a specific mass-to-charge ratio, then quantitation of wild type protein is achieved, but polymorphic variants with amino acid substitutions are not detected due to mass changes
Solution Approach 1:
The mass spectrum is segmented into multiple monitoring regions corresponding to different mass-to-charge ratios. Instead of monitoring only a single m/z ratio for wild type protein, the method monitors multiple discrete m/z ratios (e.g., 1089.8±0.5, 1090.23±0.5) to detect both wild type and polymorphic variants simultaneously, thereby preventing loss of information about variant forms
Solution Approach 2:
The method changes the monitoring parameter from a single fixed mass-to-charge ratio to multiple discrete mass-to-charge ratios. By adjusting the m/z ratio parameters in the mass spectrometry analysis, the system can identify and quantify different protein forms (wild type and variants) based on their distinct mass characteristics
2Ease of manufacture
If conventional mass spectrometry monitors only wild type protein at a specific m/z ratio, then quantitation is simplified, but detection of novel variants with extra amino acids is missed
Solution Approach 1:
The mass spectrometry method is designed to serve multiple functions simultaneously: it can detect and quantify both the wild type protein and multiple polymorphic variants (including novel variants with extra amino acids) using the same analytical system. By monitoring multiple mass-to-charge ratios, the method provides universal detection capability across different protein forms without requiring separate analysis protocols
3Adaptability or versatility
If amino acid substitutions due to polymorphisms are present in larger polypeptides, then protein diversity increases, but mass changes 'hide' the polymorphic variants from detection
Solution Approach 1:
The method adds a dimensional approach to mass spectrometry analysis by monitoring multiple discrete mass-to-charge ratio dimensions simultaneously. Instead of focusing on a single m/z dimension for wild type protein, the analysis spans multiple m/z dimensions (e.g., 1089.8±0.5, 1090.23±0.5), allowing polymorphic variants with different mass characteristics to be visualized and detected in this expanded dimensional space
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 precise detection and quantitation of IGF-2 variants, overcoming the limitations of conventional methods by accurately identifying and measuring polymorphic forms, enhancing the sensitivity and specificity of IGF-2 analysis.
Implementation Method 1
ionizing IGF-2 in the sample to produce one or more ions detectable by mass spectrometry
Implementation Method 2
detecting one or more of the ions comprising an ion with a mass-to-charge ratio of 1089.8±0.5 by mass spectrometry
Implementation Method 3
the sample may be purified by high performance liquid chromatography (HPLC) prior to ionization
Implementation Method 4
the sample may be purified by solid phase extraction (SPE) prior to ionization
Data Source
AI summary
Methods are provided for detecting and/or quantifying insulin-like growth factor-2 (IGF-2) variant(s) in a sample. Methods provided herein are further directed to using the detected ion or ions to determine the presence of IGF2 variant(s) in the sample.