Sodium methanethiosulfonate is widely used in biochemical research, particularly in protein studies. It serves as a modifying agent for cysteine residues in proteins, enabling the introduction of specific functional groups or labels. This chemical is valuable in site-directed mutagenesis and protein engineering, allowing researchers to investigate protein structure, function, and interactions. Additionally, it is employed in the study of enzyme mechanisms and the development of bioconjugates for therapeutic and diagnostic applications. Its ability to selectively modify thiol groups makes it a key tool in understanding redox processes and cellular signaling pathways.