2-Mercaptoethanol

2-Mercaptoethanol (also β-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:^[1]

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Biochemical properties

Proteins are denatured by 2-mercaptoethanol via its ability to cleave disulfide bonds:

cysS-Scys + 2 HOCH₂CH₂SH → 2 cysSH + HOCH₂CH₂S-SCH₂CH₂OH

By breaking the S-S bonds, the quaternary structure of the protein is disrupted.^[2] 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.^[3] In microgram quantities, 2-mercaptoethanol has been observed to have a number of possibly beneficial effects on laboratory mice.^[4]

Organic chemistry

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

References

1. ^ Knight, J. J. "2-Mercaptoethanol" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
2. ^ Chemicalland: 2-mercaptoethanol
3. ^ Yu, B.P.; Kang, C.M., Han, J.S., Kim, D.S. "Can antioxidant supplementation slow the aging process?" Biofactors 1998, Volume 7: pages93-101. "Can antioxidant supplementation slow the aging process?
4. ^ Effect of 2-mercaptoethanol on some metabolic indices of ageing of CBA/Ca inbred mice