FMK is widely used in biochemical research as an irreversible inhibitor of proteases. It is particularly valuable in studying enzyme mechanisms and pathways, as it forms covalent bonds with active site residues, effectively blocking enzyme activity. This property makes it a crucial tool for identifying and characterizing protease functions in various biological processes, including apoptosis, inflammation, and protein degradation. Additionally, FMK-based probes are utilized in activity-based protein profiling (ABPP) to map protease activity in complex biological systems, aiding in drug discovery and the development of targeted therapies. Its application extends to studying viral proteases, where it helps in understanding viral replication and designing antiviral drugs.