S-Phenylsulfonylcysteine (SPSC) is primarily utilized in biochemical research as a tool to study enzyme mechanisms and protein interactions. It serves as a specific inhibitor for certain enzymes, particularly those involved in cysteine metabolism, aiding in understanding their function and regulation. SPSC is also employed in proteomics to investigate post-translational modifications of proteins, especially those involving cysteine residues. Additionally, it has applications in the development of therapeutic agents targeting diseases where cysteine-related enzymes play a critical role, such as cancer and neurodegenerative disorders. Its ability to modulate enzyme activity makes it a valuable compound in drug discovery and biochemical studies.