Heteroaromatic sulfones react with cysteine via nucleophilic aromatic substitution, providing a mechanistically selective and irreversible scaffold for cysteine conjugation. Here we evaluate a library of heteroaromatic sulfides with different oxidation states, heteroatom substitutions, and a series of electron donating and electron-withdrawing substituents. Select substitutions profoundly influence reactivity and stability compared to conventional cysteine conjugation reagents, increasing the reaction rate by >3-orders of magnitude. The findings establish a series of synthetically accessible electrophilic scaffolds tunable across multiple tunable centers. New electrophiles and their corresponding alkyne-conjugates were profiled directly in cul-tured cells, achieving thiol saturation in a few minutes at sub-millimolar concentrations. Direct addition of desthiobiotin-functionalized probes to cultured cells simplified enrichment and elution to enable mass spectrometry discovery of >3000 reactive and/or accessible thiols labeled in their native cellular environments in a fraction of the standard analysis time. Surprisingly, only 1/2 of annotated cysteines were identified by both iodoacetamide-desthiobiotin and methylsulfonylbenzothiazole-desthiobiotin in replicate experiments, demonstrating complementary detection by mass spectrometry analysis. These probes offer advantages over existing cysteine alkylation reagents, including accelerated reaction rates, improved stability, and robust ionization for mass spectrometry applications. Overall, heteroaromatic sulfones provide modular tunability, shifted chromatographic elution times, and superior in-cell cysteine profiling for in-depth proteome-wide analysis and covalent ligand discovery.

中文翻译：

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可调杂芳族砜增强细胞内半胱氨酸分析

杂芳族砜通过亲核芳香取代与半胱氨酸反应，为半胱氨酸缀合提供机械选择性和不可逆支架。在这里，我们评估了具有不同氧化态、杂原子取代和一系列给电子和吸电子取代基的杂芳族硫化物库。与传统的半胱氨酸偶联试剂相比，选择取代对反应性和稳定性产生了深远的影响，将反应速率提高了 > 3 个数量级。研究结果建立了一系列可合成的可跨多个可调中心可调的亲电支架。新的亲电子试剂及其相应的炔烃偶联物直接在培养的细胞中进行分析，在几分钟内以亚毫摩尔浓度实现硫醇饱和。将脱硫生物素功能化探针直接添加到培养细胞中简化了富集和洗脱，从而能够在标准分析时间的一小部分内通过质谱发现在其天然细胞环境中标记的 >3000 个反应性和/或可接近的硫醇。令人惊讶的是，在重复实验中，只有 1/2 的注释半胱氨酸被碘乙酰胺-脱硫生物素和甲基磺酰基苯并噻唑-脱硫生物素鉴定，证明了质谱分析的互补检测。与现有的半胱氨酸烷基化试剂相比，这些探针具有优势，包括加快反应速率、提高稳定性以及适用于质谱应用的稳定电离。总体而言，杂芳族砜具有模块化可调性、色谱洗脱时间变化、