biochemistry Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, a ...

, phenylmethylsulfonyl fluoride (PMSF) is a

serine protease Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins. Serine serves as the nucleophilic amino acid at the (enzyme's) active site. They are found ubiquitously in both eukaryotes and prokaryotes. Serin ...

inhibitor (serine hydrolase inactivator) commonly used in the preparation of cell lysates. PMSF does not inactivate all

s. The effective concentration of PMSF is between 0.1 - 1 mM. The half-life is short in aqueous solutions (110 min at pH 7, 55 min at pH 7.5, and 35 min at pH 8, all at 25 °C). At 4˚C, pH 8, PMSF is almost completely degraded after 1 day. Stock solutions are usually made up in anhydrous

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

isopropanol Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable, organic compound with a pungent alcoholic odor. Isopropyl alcohol, an organic polar molecule, is miscible in water, ethanol, an ...

, or

corn oil Corn oil (North American) or maize oil (British) is oil extracted from the germ of corn (maize). Its main use is in cooking, where its high smoke point makes refined corn oil a valuable frying oil. It is also a key ingredient in some margarin ...

and diluted immediately before use. PMSF reacts specifically with the active site

serine Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − ...

residue in serine hydrolases. It does not bind to any other serine residues in the protein. This is a result of the hyperactivity of that serine residue caused by the specific environmental conditions in the enzyme's active site (

catalytic triad A catalytic triad is a set of three coordinated amino acid residues that can be found in the active site of some enzymes. Catalytic triads are most commonly found in hydrolase and transferase enzymes (e.g. proteases, amidases, esterases, aminoac ...

). Because PMSF bonds covalently to the enzyme, the complex can be viewed by X-ray crystallography; it can therefore be used as a chemical label to identify an essential active site serine in an enzyme. :Enzyme(active)Ser-O-H + F-SO₂CH₂C₆H₅ → EnzymeSer-O-SO₂CH₂C₆H₅ + HF :Serine protease + PMSF → Irreversible enzyme-PMS complex + HF The

median lethal dose In toxicology, the median lethal dose, LD50 (abbreviation for " lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a given substance. The value of LD50 for a substance is the dose re ...

between 150–215 mg/kg (

acetylcholine esterase Acetylcholinesterase ( HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme that catalyzes the breakdown of ac ...

inactivator). PMSF should be handled only inside a fume hood and while wearing gloves.

DMSO Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula . This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and is ...

is sometimes recommended as solvent for stock solutions, but should not be used as it makes intact skin permeable to PMSF.

Stability

The stability of PMSF in aqueous solutions is low, as it undergoes hydrolysis with water. PMSF is reportedly stable for ~6 months at -20˚C in

, and 9 months at room temperature in 100%

Insensitive serine enzymes

Some proteins structure limit the accessibility of comparatively bulky PMSF, and therefore PMSF is inactive against these serine enzymes like palmitoyl-protein thioesterase. Alternative sulfonyl fluoride reagents like p-APMSF and HDSF, have altered access to native folded protein structures, and may react with serine enzymes that PMSF cannot efficiently react with. This altered selectivity between sulfonyl fluoride reagents has been used to classify and isolate particular types of serine enzymes.

References

External links

* The

MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibito ...

online database for

peptidase A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do ...

s and their

inhibitor Inhibitor or inhibition may refer to: Biology * Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity * Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotransmi ...

s
PMSF
{{DEFAULTSORT:Pmsf Protease inhibitors Serine protease inhibitors Sulfonyl halides

Stability

Insensitive serine enzymes

See also

References

External links