3,4-dichloroisocoumarin

**3,4-Dichloroisocoumarin** is a synthetic small molecule that acts as a potent irreversible inhibitor of serine proteases. It covalently binds to the active site serine residue in the catalytic triad of these enzymes and thereby blocks their activity. This compound has been widely used in biochemical research to functionally characterize the catalytic activities of various proteases—including factor D (a component of the complement system), trypsin-like enzymes, elastase and other esterases[9][8][5]. Its mechanism-based inhibition makes it valuable for studying enzyme structure and function as well as for probing apoptotic pathways (e.g., blocking internucleosomal DNA cleavage in thymocytes)[5]. It is not approved for clinical use and is primarily available for laboratory research applications[2][7].

Other names

3,4-dichloroisocoumarin3,4-dichloroisochromen-1-one3,4-dichloro-1H-isochromen-1-one3,4-dichloroisochromén-1-one3,4-dichloroisocoumarin serine protease inhibitor51050-59-0