2-Mercaptoethanol

2-Mercaptoethanol (also &beta;-mercaptoethanol) is the chemical compound with the formula HOCH2CH2SH. It is a hybrid of ethylene glycol, HOCH2CH2OH, and 1,2-ethanedithiol, HSCH2CH2SH. ME or βME, as it is commonly abbreviated, is used to reduce disulfide bonds and can act as a biological antioxidant by scavaging hydroxyl radicals (amongst others). It is widely used because the hydroxyl group confers solubility in water and lowers the volatility. Due to its diminished vapor pressure, its odour, while unpleasant, is less objectionable than related thiols.

ME is prepared by the action of hydrogen sulfide on ethylene oxide:


 * [[Image:2-mercaptoethanol-preparation-2D-skeletal.svg|400px|Reaction scheme for the preparation of 2-mercaptoethanol from ethylene oxide and hydrogen sulfide]]

Biochemical properties
Proteins are denatured by 2-mercaptoethanol via its ability to cleave disulfide bonds:
 * cysS-Scys +  2 HOCH2CH2SH   →   2 cysSH  +  HOCH2CH2S-SCH2CH2OH


 * [[Image:Disulfide-bond-cleavage-by-2-mercaptoethanol-2D-skeletal.svg|400px|Reaction scheme for the cleavage of disulfide bonds by 2-mercaptoethanol]]

By breaking the S-S bonds, the quaternary structure of the protein is disrupted. Because of its ability to disrupt the quaternary structure of proteins, it is used in the analysis of proteins.

2-Mercaptoethanol is often used interchangeably with dithiothreitol (DTT) or the odorless tris(2-carboxyethyl)phosphine (TCEP) in biological applications.

Biomedical consequences
2-Mercaptoethanol is one of the few chemicals that extends the maximum as well as the median life span of mice. In microgram quantities, 2-mercaptoethanol has been observed to have a number of possibly beneficial effects on laboratory mice.

Organic chemistry
ME reacts with aldehydes and ketones to give the corresponding oxathiolanes:


 * [[Image:Oxathiolane-formation-with-2-mercaptoethanol-2D-skeletal.svg|400px|Reaction scheme for the formation of oxathiolanes by reaction of 2-mercaptoethanol with aldehydes or ketones]]