Low-Toxicity Sulfonium-Based Probes for Cysteine-Specific Profiling in Live Cells

Area of Science:

• Biochemistry
• Chemical Biology
• Proteomics

Background:

• Cysteine is a low-abundance amino acid crucial for protein function, post-translational modifications, and drug development.
• Identifying reactive cysteine residues is essential for understanding protein regulation and disease mechanisms.
• Current chemical proteomic probes have limitations in specificity, stability, or cellular compatibility.

Purpose of the Study:

• To develop novel chemical proteomic probes for comprehensive assessment of reactive-cysteine-containing proteins in human cells.
• To introduce a new class of sulfonium-based probes for specific labeling of reactive cysteine residues.
• To evaluate the performance of these probes compared to conventional methods.

Main Methods:

• Synthesis and characterization of a set of cysteine-reactive sulfonium-based (C-Sul) probes.
• Assessment of probe stability, cellular uptake, and specificity toward reactive cysteines.
• Comparison of C-Sul probes with iodoacetamide-based probes regarding cell viability and proteomic profiling compatibility.
• Application of C-Sul probes for quantitative proteomic profiling of reactive cysteine residues.

Main Results:

• Water-soluble C-Sul probes exhibit significantly enhanced stability and cellular uptake.
• C-Sul probes demonstrate high specificity for reactive cysteines.
• Unlike iodoacetamide, C-Sul probes show no inhibitory effects on cell viability.
• C-Sul probes are compatible with quantitative proteomic profiling under biorelevant conditions.

Conclusions:

• C-Sul probes represent a novel and effective chemical proteomic tool for labeling reactive cysteine residues.
• These probes overcome limitations of conventional methods, enabling proteomic analysis under physiologically relevant conditions.
• C-Sul probes are proposed as optimal tools for cysteine profiling in basic research and drug development.