2mercaptoethanol

2-mercaptoethanol, also called beta-mercaptoethanol (BME), is a small organosulfur compound used widely as a reducing agent in biochemistry. Its chemical formula is HO-CH2-CH2-SH, and it consists of a hydroxyl group attached to a two-carbon chain bearing a thiol group. At room temperature it is a colorless, volatile liquid with a distinctive malodorous odor.

It is miscible with water and many organic solvents. It is easily oxidized in air to form the disulfide (HO-CH2-CH2-S-S-CH2-CH2-OH). The thiol has a pKa around 9.6, so in neutral solutions it exists partly as the thiolate ion, which participates in redox reactions and enables reduction of disulfide bonds.

In biochemistry, 2-mercaptoethanol is used as a reducing agent to break disulfide bonds in proteins and nucleic acid preparations, helping to denature proteins and maintain cysteine residues in a reduced state. In SDS-PAGE sample buffers it is commonly used at about 5-10% v/v to ensure complete unfolding of proteins; it is often replaced by dithiothreitol (DTT) in some protocols due to odor and handling considerations.

Safety and handling: It is toxic and a skin, eye, and respiratory irritant. Vapors are highly odorous and can be detected at very low concentrations. It should be handled in a fume hood with appropriate PPE; store refrigerated in a tightly sealed container away from oxidizers, and dispose of according to regulations. It is flammable and reactive with oxidizers.