AEBSF or 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride is a water-soluble, irreversible serine protease inhibitor with a molecular weight of 239.5 Da. It inhibits proteases like chymotrypsin, kallikrein, plasmin, thrombin, and trypsin. The specificity is similar to the inhibitor PMSF, nevertheless AEBSF is more stable at low pH values. Typical usage is 0.1 - 1.0 mM. AEBSF or 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride is a water-soluble, irreversible serine protease inhibitor with a molecular weight of 239.5 Da. It inhibits proteases like chymotrypsin, kallikrein, plasmin, thrombin, and trypsin. The specificity is similar to the inhibitor PMSF, nevertheless AEBSF is more stable at low pH values. Typical usage is 0.1 - 1.0 mM. Both AEBSF and PMSF are sulfonyl fluorides and are sulfonylating agents. Sulfonyl fluorides act by reacting with the hydroxy group of the active site serine residue to form a sulfonyl enzyme derivative. This derivative may be stable for long periods of time except at high pH.