Tunable heteroaromatic azoline thioethers (HATs) for cysteine profiling

Area of Science:

• Chemical Biology
• Organic Chemistry
• Biochemistry

Background:

• Cysteine modification is crucial for biochemical studies.
• Existing methods often lack selectivity, speed, or tracelessness.
• Development of novel chemical tools for cysteine labeling is needed.

Purpose of the Study:

• To develop novel, hydrolytically stable heteroaromatic azoline thioethers (HATs) for cysteine labeling.
• To demonstrate the selective, rapid, and efficient covalent modification of cysteine under physiological conditions.
• To showcase the traceless decoupling of HAT-cysteine conjugates and their umpolung capability.

Main Methods:

• Synthesis of hydrolytically stable heteroaromatic azoline thioethers (HATs).
• Application of HAT probes for covalent labeling of cysteine in peptides and proteins.
• Analysis of cysteine-azoline conjugate stability and traceless decoupling under reducing conditions.
• Demonstration of umpolung reactivity for cysteine modification with various nucleophiles.
• Mass spectrometry-based analysis to determine mass sensitivity enhancement.

Main Results:

• HAT probes provide highly selective, rapid, and efficient covalent labeling of cysteine.
• Cysteine-azoline conjugates are stable but can be tracelessly decoupled under reducing conditions.
• HAT probes exhibit umpolung capability, reversing nucleophilic cysteine to electrophilic dehydroalanine (Dha).
• Mass sensitivity of modified peptides and proteins is increased by 100-fold compared to classical methods.
• HAT probes enable specific cysteine modification within complex cell lysate mixtures.

Conclusions:

• HAT probes represent a versatile new class of reagents for selective cysteine modification.
• The traceless nature and umpolung capability of HATs offer unique advantages in chemical biology.
• HAT probes significantly enhance detection sensitivity, facilitating proteomic studies.