PMSF (phenylmethylsulfonyl fluoride) is a small molecule inhibitor of serine proteases, including trypsin, chymotrypsin, thrombin, and papain. PMSF binds covalently to the serine residue in the catalytic site of the enzyme, causing its irreversible inhibition. Although broad-acting, one drawback of this inhibitor is its limited solubility and brief half-life. Hence it is recommended to use solvents such as methanol, ethanol, or isopropanol to dissolve the compound before usage. PMSF does not inhibit all serine proteases and is often included in an inhibitor cocktail to extend the range of its proteolytic activity. PMSF is often added to lysates and extracts to protect proteins from degradation. Visit the supplier page for more information.