3-Isothioureidopropionic acid is primarily utilized in biochemical research as a reagent for studying enzyme activity and protein interactions. It is often employed in the modification of proteins and peptides, aiding in the investigation of their structure and function. Additionally, it serves as a precursor in the synthesis of various biologically active compounds, contributing to the development of pharmaceuticals and therapeutic agents. Its applications also extend to the field of organic synthesis, where it is used to create intermediates for further chemical transformations.