N-acryloylindole probes for selective cysteine profiling
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Solution Overview
Problem
Conventional cysteine-reactive probes, such as iodoacetamide alkyne (IAA), suffer from side reactions with other nucleophilic amino acids, low biostability, and high toxicity, limiting their application in cysteine profiling, especially in live cells due to slow reactivity and poor selectivity.
Innovation Solution
Development of N-acryloylindoles (NAIs) with an acrylamide warhead activated by the indole nitrogen, which are further functionalized with an alkyne handle to create N-acryloylindole-alkynes (NAIAs) as cysteine-reactive probes, offering faster reaction kinetics and improved selectivity and biostability, enabling labeling of cysteines in both cell lysates and live cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If iodoacetamide alkyne (IAA) is used as a cysteine probe, then cysteine labeling can be achieved, but side reactions with other nucleophilic amino acids occur and selectivity is poor
Solution Approach 1:
The patent changes the chemical parameters of the cysteine probe by replacing the iodoacetamide group with an acrylamide group. This parameter change fundamentally alters the reaction mechanism from alkyl halide substitution to Michael addition, improving cysteine selectivity while maintaining labeling reliability. The acrylamide group's electrophilic character is tuned to specifically react with thiol groups over other nucleophilic amino acids.
Solution Approach 2:
The patent introduces local quality enhancement by adding electron-withdrawing groups (such as fluorine atoms or additional carbonyl groups) at specific positions on the acrylamide scaffold. This local modification increases the electrophilicity of the acrylamide carbon specifically at the reaction site, enhancing both reactivity toward cysteine and selectivity against other amino acids without affecting the overall probe structure.
2Reliability
If iodoacetamide alkyne (IAA) is used for cysteine profiling, then cysteine capture is possible, but reactivity is slow requiring large excess of probe
Solution Approach 1:
The patent changes the kinetic parameters of the probe by switching from iodoacetamide to acrylamide chemistry. The acrylamide group undergoes Michael addition with thiols, which has inherently faster second-order rate constants compared to the SN2 reaction of iodoacetamide. This parameter change enables rapid labeling at physiological concentrations without requiring large probe excess.
Solution Approach 2:
The patent enhances the dynamic response of the probe by designing the acrylamide group to be highly reactive under physiological conditions. The electron-withdrawing substituents on the acrylamide scaffold dynamically increase the electrophilic character during the reaction, accelerating the labeling kinetics and enabling complete cysteine capture within practical timeframes at low probe concentrations.
3Productivity
If high concentration of IAA is used for adequate labeling, then cysteine labeling efficiency improves, but cellular toxicity increases and biostability decreases
Solution Approach 1:
The patent changes the concentration parameter requirement by switching to acrylamide chemistry, which achieves complete labeling at much lower probe concentrations (nanomolar to low micromolar range) compared to iodoacetamide. This parameter change eliminates the need for high probe concentrations that cause cellular toxicity, while maintaining high labeling efficiency through the inherent reactivity of the acrylamide-thiol Michael addition.
Solution Approach 2:
The patent replaces the unstable iodoacetamide group with the more biostable acrylamide group. The acrylamide probe is chemically more stable in biological environments, resisting hydrolysis and other degradation pathways that limit iodoacetamide biostability. This allows the probe to maintain its labeling capability throughout the experimental duration without decomposing or losing efficacy.
4Stability of the object's composition
If acrylamide compounds are used for cysteine profiling, then biostability is improved, but reactivity in aqueous buffer solution is low
Solution Approach 1:
The patent introduces local quality enhancement by adding electron-withdrawing groups (such as fluorine atoms or additional carbonyl groups) at specific positions on the acrylamide scaffold. This local modification increases the electrophilicity of the acrylamide carbon specifically at the reaction site, enhancing both reactivity toward cysteine and selectivity against other amino acids without affecting the overall probe structure.
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
NAIAs demonstrate enhanced reactivity and selectivity for cysteines over other amino acids, allowing for effective cysteine profiling and imaging in both in vitro and live-cell contexts, with reduced cellular toxicity and improved stability, expanding the pool of ligandable cysteines and proteins that can be targeted for therapeutic applications.
Implementation Method 1
excellent selectivity for the thiol group on cysteine through the thiol-Michael addition reaction
Data Source
AI summary
The subject invention pertains to a new class of compounds, N-acryloylindole (NAIs), and methods of using NAIs as cysteine-reactive probes for proteome-wide cysteine profiling and imaging of thiol oxidative modifications. NAIs are capable of imaging oxidized thiols in cells facing oxidative stress by confocal fluorescence microscopy. NAIs can capture populations of cysteines, particularly those involved in gene expression and regulation.