Protease Assay Substrate with Beta-Sheet Spacers
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Solution Overview
Problem
Current methods for measuring thrombin generation in blood samples are limited, as they cannot accurately detect physiologically active thrombin due to fluorescence signal quenching in whole blood and fail to distinguish between free and bound thrombin, particularly thrombin bound to alpha-2-macroglobulin.
Innovation Solution
A novel substrate with a detectable label linked to a cleavage sequence by C-terminal and N-terminal spacers forming a beta sheet, which emits different signals before and after cleavage, allowing for the measurement of protease activity and coagulation monitoring in biological samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluorogenic substrates are used to measure thrombin generation in whole blood, then thrombin generation can be detected, but fluorescence signal is quenched by red blood cells making measurement inaccurate
Solution Approach 1:
The patent uses an optical clearant agent as an intermediary substance that selectively binds to hemoglobin in red blood cells. This clearant displaces hemoglobin from the fluorogenic substrate, preventing quenching of the fluorescence signal while allowing thrombin to continue cleaving the substrate for detection. The clearant acts as a mediator between the thrombin substrate system and the red blood cells, eliminating the harmful quenching effect.
2Measurement precision
If conventional fluorogenic substrates are used, then thrombin generation can be measured, but free and bound thrombin cannot be distinguished
Solution Approach 1:
The patent applies local quality by making the substrate responsive to different local conditions. The fluorogenic substrate is designed to exhibit different fluorescence characteristics when cleaved by free thrombin versus bound thrombin, allowing differentiation of thrombin states. The substrate's fluorescent properties change locally based on the enzymatic environment, providing information about both free and bound thrombin activity simultaneously.
3Measurement precision
If sample preparation steps are added to remove interference, then measurement accuracy improves, but assay complexity and time increase
Solution Approach 1:
The patent employs a self-service mechanism where the optical clearant agent automatically binds to hemoglobin and clears the interference without requiring manual sample preparation steps. The clearant is added to the whole blood sample and performs the clearance function in situ, eliminating the need for separate centrifugation, filtration, or plasma separation steps. This self-clearing approach maintains accuracy while simplifying the overall assay procedure.
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 method effectively determines the presence and generation of activated proteases like thrombin in whole blood, distinguishing between free and bound thrombin, and provides accurate monitoring of coagulation, even in the presence of anticoagulants, without requiring sample preparation.
Implementation Method 1
the detectable label emits a first signal associated with the substrate and second signal associated with a cleaved product
Implementation Method 2
C-terminal and N-terminal spacers that form a beta sheet
Implementation Method 3
a cleavage sequence for the protease... determining the activity of the protease by measuring the change in the first or second signal over time
Data Source
AI summary
A method of determining generation of an activated protease in a biological sample is provided. The method comprises the steps of exposing a biological sample to a substrate for the activated protease, wherein the substrate comprises a detectable label linked to a cleavage sequence for the activated protease by C-terminal and N-terminal spacers that form a beta-sheet, and wherein the detectable label emits a first signal associated with the substrate and second signal associated with a cleaved product; and determining the generation of the activated protease by measuring the change in the first or second signal over time.