NT-proBNP Quantification with Affinity Purification and LC-MS/MS
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Solution Overview
Problem
Current assays for determining N-terminal pro-hormone BNP (NT-proBNP) concentrations lack standardization, leading to significant variations in results and complicating diagnostic decisions, particularly in heart failure diagnosis, due to differences in antibodies used and the lack of a primary reference standard material.
Innovation Solution
A method involving affinity purification, enzymatic digestion, and liquid chromatography-mass spectrometry analysis is employed to isolate and quantify NT-proBNP, using specific antibodies that target non-glycosylated epitopes and labeled peptide standards, enabling accurate detection and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional immunoassay methods are used for NT-proBNP determination, then the assay can be performed with commercially available reagents, but significant variations in results occur due to lack of standardization and different antibody specificities
Solution Approach 1:
The patent changes the measurement parameter from antibody-based binding affinity to mass-to-charge ratio detected by mass spectrometry. This fundamental parameter change eliminates variability introduced by different antibody specificities and assay conditions, providing a unified measurement standard across all laboratories.
Solution Approach 2:
The patent replaces the mechanical/chemical binding system of immunoassays with a physical detection system based on mass spectrometry. By substituting antibody-antigen binding with direct mass measurement of peptide fragments, the method eliminates the need for standardized antibodies while achieving superior measurement precision.
2Quantity of substance
If glycosylated NT-proBNP forms are measured using conventional assays, then the assay detects circulating forms, but glycosylation causes confusion about relevant forms and affects measurement accuracy
Solution Approach 1:
The patent segments the NT-proBNP molecule into characteristic peptide fragments through proteolytic digestion. By measuring specific peptide sequences rather than the entire glycosylated protein, the method avoids interference from glycosylation variants while maintaining detection of all NT-proBNP forms.
Solution Approach 2:
The patent introduces proteolytic enzymes as intermediaries that convert complex glycosylated NT-proBNP into simplified peptide fragments. These enzyme-digested peptides serve as reliable intermediaries for quantification, eliminating the complexity introduced by glycosylation while preserving the original molecule's identity information.
3Measurement precision
If a primary reference standard material is established using the disclosed method, then measurement precision and standardization improve, but the device complexity and method sophistication increase
Solution Approach 1:
The patent performs preliminary proteolytic digestion of NT-proBNP into characteristic peptide fragments before mass spectrometry analysis. This preliminary action simplifies the subsequent measurement by converting complex glycosylated proteins into smaller, more easily detected peptides with unique mass signatures, establishing a standardized reference approach.
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 a robust and reliable reference for NT-proBNP quantification, reducing variations and improving sensitivity, allowing for standardized diagnostic assays and calibration of existing methods, thereby enhancing the accuracy of heart failure diagnosis.
Implementation Method 1
extracting and isolating NT-proBNP from the sample using an affinity purification method
Implementation Method 2
subjecting said isolated NT-proBNP and peptide standard to enzymatic digestion
Implementation Method 3
detecting at least one peptide in the resulting mixture, using liquid chromatography-mass spectrometry analysis
Implementation Method 4
detecting at least one peptide in the resulting mixture, using liquid chromatography-mass spectrometry analysis with subsequent mass spectrometric detection
Data Source
AI summary
A reference method for quantifying the total amount of NT-proBNP in a sample, independent of its degree of glycosylation, involving LC-MS/MS analysis of a sample that has been subjected to affinity purification and subsequent digestion.