Granzyme B Cleavable Peptide Probe for Cytotoxicity Detection
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Solution Overview
Problem
Current methods for detecting granzyme B activity in CD8+ T cells are limited, as existing probes cannot distinguish between active and inactive forms of the enzyme, and have low catalytic efficiency, making them unsuitable for accurately monitoring cytotoxic activity in cancer treatment responses.
Innovation Solution
Development of a probe comprising a granzyme B-cleavable hexapeptide sequence (P4-P3-P2-P1-X1-X2) conjugated with a detectable moiety, where P4 is I or V, P3 is E or Q, P2 is any amino acid, P1 is D, X1 is A, S, W, or R, and X2 is G or R, which generates a cleaved peptide detectable by a change in signal or physicochemical properties upon cleavage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing probes (antibodies, fusion proteins, IEPD-based constructs) are used for detecting granzyme B, then detection capability is provided, but they cannot distinguish between active and inactive forms of the enzyme and have low catalytic efficiency
Solution Approach 1:
The patent modifies the peptide sequence parameters by extending the IEPD tetrapeptide to a hexapeptide format (P4-P3-P2-P1-X1-X2) with specific amino acid constraints. This structural parameter change enables the probe to achieve both high catalytic efficiency (kcat/KM > 1×10^5) and the ability to distinguish active from inactive granzyme B forms through fluorescence signal changes upon cleavage
Solution Approach 2:
The probe combines multiple functional components into a composite structure: a granzyme B-cleavable hexapeptide sequence conjugated to a detectable moiety (such as a fluorophore). This composite design integrates the recognition function (peptide sequence) with the detection function (detectable moiety), enabling simultaneous high catalytic efficiency and detection specificity
2Quantity of substance
If standard methods (LDH, MTS, 51Cr release assays) are used for monitoring CD8+ T cell cytotoxicity, then bulk cytotoxicity can be measured, but T cell-specific anticancer responses cannot be distinguished
Solution Approach 1:
The patent extracts the specific functional element (granzyme B enzyme) that mediates T cell cytotoxicity from the bulk cell population measurement. By using a granzyme B-cleavable hexapeptide probe, the method isolates and measures only the granzyme B-specific activity, thereby distinguishing T cell-specific anticancer responses from bulk cytotoxicity
Solution Approach 2:
The granzyme B-cleavable hexapeptide probe acts as an intermediary molecule that specifically interacts with active granzyme B enzyme. This intermediary enables the translation of enzymatic activity into a detectable signal (fluorescence change), providing a precise readout of T cell cytotoxic function without measuring bulk cytotoxicity
3Measurement precision
If probes with limited catalytic efficiency (Vmax in pmol min−1 range, kcat/KM around mM−1 s−1) are used, then detection is possible, but accurate monitoring of cytotoxic activity in cancer treatment responses is hindered
Solution Approach 1:
The patent dramatically improves catalytic efficiency by changing the peptide structure from tetrapeptide to hexapeptide format with optimized amino acid sequences. The resulting probes achieve kcat/KM values greater than 1×10^5, representing a significant parameter improvement over existing probes with kcat/KM around mM−1 s−1, enabling accurate monitoring of cytotoxic activity
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 probe achieves high specificity and sensitivity for granzyme B, with a KM of less than 30 μM and a Kcat/KM value of greater than 1×10^5, enabling accurate detection of enzymatically active granzyme B and distinguishing it from inactive forms, thus facilitating the assessment of cancer cell death and immunotherapy efficacy.
Implementation Method 1
the probe comprising a granzyme B cleavable peptide conjugated or bound to a detectable moiety, wherein the granzyme B cleavable peptide comprises, consists essentially of, or consists of a hexapeptide sequence... The peptide is cleaved between the P1 and X1 amino acid residues
Data Source
AI summary
The present disclosure relates to the development of novel cleavable peptide probes for use in detecting granzyme B, as well as methods for using the probes in medical and biological settings. The probes may comprise a fluorescent moiety conjugated or bound to the peptide, and quencher moiety conjugated or bound to the peptide and upon cleavage of the peptide, the fluorescent moiety becomes dequenched.