PMSF stands for Phenylmethylsulfonyl fluoride. It is used as an irreversible inhibitor of serine protease activity for example in protein purification or co-immunoprecipitation. It has no effect on other proteases that might be present. It can also inactivate some non-proteolytic enzymes that contain serine in the active site.
Molecular W.: 174.19
You can buy PMSF for example at Pierce or Sigma.
PMSF is not soluble in water, dissolve in isopropanol, ethanol or methanol. 200 mM stock solution (0.035 g/mL) is stable for months at 4°C, although storage at -20 is probably better. A common final concentration of PMSF is 1mM. PMSF is extremely toxic, and preparation of solutions should be done very carefully. PMSF is not stable in alkaline conditions, or in water. For disposal, add alkali in water and wait to dispose.
PMSF is extremely poisonous and should be handled carefully.