Introduction: Cysteine is a versatile amino acid for selective chemical modification of proteins with both chemical and biological innovations, which plays a key role in different organic reactions.

Materials and Methods: Chemical modification of proteins is a rapidly expanding area in chemical biology. Selective installation of biochemical probes has led to a better understanding of natural protein modification and macromolecular function. In other cases, such as chemical alterations, the protein function has entirely changed. This review paper considers the organic reaction of cysteine, the reactivity of this α-amino acid containing sulfur, and several methodologies are also discussed. Herein, we focused on the reaction of cysteine and its application in organic synthesis, which includes addition, condensation, substitution, oxidation, and ring-opening reactions.

Results and Discussion: Hence monitoring of cysteine is pivotal through the preparation of some fluorescent probes to detect cysteine in high sensitivity. Also, a bibliometric analysis was carried out using Web of Science and Scopus databases that demonstrated significant contributions being observed in organic synthesis. Analysis of keywords revealed that research hotspots were cysteine, sensor, unclassified drug, and amino acid.

Conclusion: Therefore, it seems that future research focuses on using cysteine amino acids in various fields as natural products and organic reactions. This focused review highlights the enduring utility of cysteine in protein modification and sensor preparation, with a special focus on recent innovations in chemistry and biology associated with such modifications.

简介：半胱氨酸是一种多功能氨基酸，具有化学和生物创新，可用于蛋白质的选择性化学修饰，在不同的有机反应中起着关键作用。

材料和方法：蛋白质的化学修饰是化学生物学中一个快速扩展的领域。生化探针的选择性安装使人们更好地了解天然蛋白质修饰和大分子功能。在其他情况下，例如化学改变，蛋白质功能已经完全改变。这篇综述论文考虑了半胱氨酸的有机反应、这种含硫的 α-氨基酸的反应性，还讨论了几种方法。在此，我们重点研究了半胱氨酸的反应及其在有机合成中的应用，包括加成、缩合、取代、氧化和开环反应。

结果和讨论：因此，通过制备一些荧光探针以高灵敏度检测半胱氨酸，监测半胱氨酸至关重要。此外，使用 Web of Science 和 Scopus 数据库进行了文献计量分析，表明在有机合成中观察到了显着贡献。关键词分析显示，研究热点为半胱氨酸、传感器、未分类药物和氨基酸。

结论：因此，似乎未来的研究重点是将半胱氨酸氨基酸作为天然产物和有机反应在各个领域中使用。这篇重点综述强调了半胱氨酸在蛋白质修饰和传感器制备中的持久效用，特别关注与此类修饰相关的化学和生物学的最新创新。