PMSF
PMSF (phenylmethylsulfonyl fluoride)
To prepare a 100 mM solution, add 17.4 mg of PMSF per milliliter of isopropanol. Store at −20°C.
PMSF is inactivated in aqueous solutions. The rate of inactivation increases with increasing pH and is faster at 25°C than at 4°C. The half-life of a 20 mM aqueous solution of PMSF is ~35 min at pH 8.0. This short half-life means that aqueous solutions of PMSF can be safely discarded after they have been rendered alkaline (pH >8.6) and stored for several hours at room temperature.
An alternative to PMSF (4-[2-aminoethyl]-benzenesulfonylfluoride, hydrochloride; Pefabloc SC) is available. Pefabloc is an irreversible serine protease inhibitor, and is used at the same concentration as PMSF, but is nontoxic and stable in aqueous buffer solutions.
