2-Mercaptoethanol

2-Mercaptoethanol

Names
IUPAC name 2-Hydroxy-1-ethanethiol
Other names 2-Mercaptoethanol Thioglycol β-Mercaptoethanol
Identifiers
CAS Number	60-24-2 N
3D model (JSmol)	Interactive image
ECHA InfoCard	100.000.422
CompTox Dashboard (EPA)	DTXSID4026343
SMILES SCCO
Properties
Chemical formula	C2H6OS
Molar mass	78.13 g mol−1
Density	1.11 g cm−3
Melting point	−100 °C
Boiling point	157-158 °C
Refractive index (nD)	1.4996
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

2-Mercaptoethanol (also β-mercaptoethanol, BME, 2BME or β-met) 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 scavenging 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.

Preparation

2-Mercaptoethanol may be prepared by the action of hydrogen sulfide on ethylene oxide:

Reactions

2-Mercaptoethanol reacts with aldehydes and ketones to give the corresponding oxathiolanes. This makes 2-mercaptoethanol useful as a protecting group.

Applications

Reducing proteins

Some proteins can be 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, both the tertiary structure and the quaternary structure of some proteins can be disrupted. Because of its ability to disrupt the structure of proteins, it was used in the analysis of proteins, for instance, to ensure that a protein solution contains monomeric protein molecules, instead of disulfide linked dimers or higher order oligomers. However, since 2-mercaptoethanol forms adducts with free cysteins in addition to its toxicity and smell, nowadays the more powerful reductive dithiothreitol (DTT) is employed especially in SDS-PAGE.

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

Denaturing Ribonucleases

2-Mercaptoethanol is used in some RNA isolation procedures to eliminate ribonuclease released during cell lysis. Numerous disulfide bonds make ribonucleases very stable enzymes, so 2-mercaptoethanol is used to reduce these disulfide bonds and irreversibly denature the proteins. This prevents them from digesting the RNA during its extraction procedure.

Safety

2-Mercaptoethanol is considered a toxin, causing irritation to the nasal passageways and respiratory tract upon inhalation, irritation to the skin, vomiting and stomach pain through ingestion, and potentially death if severe exposure occurs.