(S)-2-Acetamido-3-mercaptopropanoic acid is primarily used in biochemical research as a precursor or intermediate in the synthesis of more complex molecules. It plays a significant role in the study of enzyme mechanisms, particularly those involving cysteine proteases, due to its thiol group which can interact with active sites of enzymes. This compound is also utilized in the development of pharmaceuticals, especially in the design of drugs that target specific enzymatic pathways. Additionally, it serves as a building block in peptide synthesis, where its unique structure can be incorporated into peptides to modify their properties or functions. Its applications extend to the field of biotechnology, where it is used in the preparation of modified proteins and enzymes for various industrial processes.