Activity-Based Probe Compounds for Cysteine Protease Labeling
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Solution Overview
Problem
There is a need for novel activity-based fluorescent probes that offer higher cellular uptake, target a broader spectrum of cysteine protease activities, and provide increased sensitivity of detection, particularly for cysteine proteases involved in cancer and other diseases.
Innovation Solution
Development of compounds with a phenoxymethyl ketone electrophile and a sulfonated quencher, such as Sulfo-QSY21, which are designed to target cysteine proteases with improved aqueous solubility and stability, enabling broader reactivity and enhanced in vivo labeling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fluorescent probes are used, then detection capability is provided, but cellular uptake is limited and sensitivity is insufficient
Solution Approach 1:
The patent modifies the chemical parameters of the probe by introducing a phenoxymethyl ketone electrophile and a sulfonated quencher (Sulfo-QSY21). These parameter changes increase hydrophilicity and enable broader reactivity with cysteine proteases, thereby improving both cellular uptake and detection sensitivity simultaneously.
Solution Approach 2:
The probe combines multiple functional components into a composite structure: a phenoxymethyl ketone electrophile for covalent binding to cysteine proteases, a sulfonated quencher (Sulfo-QSY21) for enhanced aqueous solubility and stability, and a fluorescent reporter. This composite design resolves the contradiction by integrating properties that collectively improve both cellular uptake and detection sensitivity.
2Adaptability or versatility
If probes with broader protease targeting are developed, then spectrum coverage increases, but probe stability decreases
Solution Approach 1:
The patent applies local quality by designing the phenoxymethyl ketone electrophile to specifically interact with the catalytic cysteine residue in the active site of proteases. This localized interaction provides broad protease targeting while the sulfonated quencher provides localized stability through enhanced aqueous solubility and resistance to non-specific binding.
Solution Approach 2:
The sulfonated quencher acts as an intermediary that mediates between the electrophilic warhead and the fluorescent reporter. It provides stability to the overall probe structure while allowing the electrophile to maintain broad reactivity with various cysteine proteases, thus resolving the contradiction between versatility and stability.
3Quantity of substance
If probe hydrophilicity is increased, then aqueous solubility improves, but molecular size increases
Solution Approach 1:
The patent changes the chemical parameter of the probe by incorporating a sulfonated quencher (Sulfo-QSY21), which introduces sulfonate groups that significantly increase aqueous solubility. This parameter change achieves improved solubility while the compact structure of the sulfonated group minimizes the increase in molecular size.
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 new probes demonstrate increased hydrophilicity, broader cysteine cathepsin labeling, and improved stability, resulting in enhanced contrast and sensitivity for non-invasive optical imaging of cancer, with a more than twenty-fold increase in tumor-specific fluorescence compared to previous probes.
Implementation Method 1
The ABPs can be distinguished from simple fluorogenic substrates by the permanent covalent bond that results from reaction of the ABP with the enzyme's active site catalytic residue
Implementation Method 2
optical probes that are recognized by enzyme targets in a biological sample often generate extremely specific signals if the fluorescence of the probe is only unleashed upon enzymatic reaction
Implementation Method 3
Development of compounds with a phenoxnymethyl ketone electrophile and a sulfonated quencher, such as Sulfo-QSY21, which are designed to target cysteine proteases with improved aqueous solubility and stability
Data Source
AI summary
Activity-based probe compounds for use in labeling a cysteine protease are provided. The compounds are targeted to the protease through a specific targeting element. The compounds additionally include a detectable element, such as a fluorescent label, a radiolabel, or a chelator. In some cases, the compounds additionally include a quenching element that is released upon reaction with the protease. Also provided are compositions comprising the compounds and methods for using the compounds, for example in labeling a protease in an animal and in visualizing a tumor in an animal.