| 2-Mercaptoethanol | |
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2-Sulfanylethan-1-ol |
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Other names
2-Hydroxy-1-ethanethiol β-Mercaptoethanol |
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| Identifiers | |
| CAS number | 60-24-2 |
| PubChem | 1567 |
| ChemSpider | 1512 |
| EC number | 200-464-6 |
| UN number | 2966 |
| DrugBank | DB03345 |
| KEGG | C00928 |
| MeSH | Mercaptoethanol |
| ChEBI | CHEBI:41218 |
| ChEMBL | CHEMBL254951 |
| RTECS number | KL5600000 |
| Beilstein Reference | 773648 |
| Gmelin Reference | 1368 |
| 3DMet | B00201 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C2H6SO |
| Molar mass | 78.133 g mol−1 |
| Exact mass | 78.013935504 g mol−1 |
| Density | 1.114 g cm−3 |
| Melting point |
−100 °C, 173 K, -148 °F |
| Boiling point |
157 °C, 430 K, 314 °F |
| log P | -0.23 |
| Vapor pressure | 100 Pa (at 20 °C) |
| Acidity (pKa) | 9.643 |
| Basicity (pKb) | 4.354 |
| Refractive index (nD) | 1.4996 |
| Hazards | |
| MSDS | msds.chem.ox.ac.uk |
| GHS pictograms | |
| GHS signal word | DANGER |
| GHS hazard statements | H301, H310, H315, H317, H318, H330, H410 |
| GHS precautionary statements | P260, P273, P280, P284, P301+310, P302+350 |
| EU classification | T N |
| R-phrases | R20/22, R24, R34, R51/53 |
| S-phrases | S26, S36/37/39, S45, S61 |
| Flash point | 68 °C |
| Explosive limits | 18% |
| Related compounds | |
| Related compounds | Ethylene glycol |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
2-Mercaptoethanol (also β-mercaptoethanol, BME, 2BME, 2-ME 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.
Contents |
2-Mercaptoethanol may be prepared by the action of hydrogen sulfide on ethylene oxide:[1]
2-Mercaptoethanol reacts with aldehydes and ketones to give the corresponding oxathiolanes. This makes 2-mercaptoethanol useful as a protecting group.[2]
Some proteins can be denatured by 2-mercaptoethanol via its ability to cleave disulfide bonds:
By breaking the S-S bonds, both the tertiary structure and the quaternary structure of some proteins can be disrupted.[3] 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 cysteines and is somewhat more toxic, dithiothreitol (DTT) is more generally employed especially in SDS-PAGE. DTT is also a more powerful reducing agent with a redox potential (at pH 7) of -0.33 V, compared to -0.26 V for 2-mercaptoethanol.[4]
2-mercaptoethanol is often used interchangeably with dithiothreitol (DTT) or the odorless tris(2-carboxyethyl)phosphine (TCEP) in biological applications.
2-mercaptoethanol is more stable than DTT (2-ME: t1/2>100h at pH6.5, t1/2=4h at pH8.5; DTT: t1/2=40h at pH6.5, t1/2=1.5h at pH8.5; Stevens et al., 1983), but has a higher volatility.[5]
2-Mercaptoethanol and related reducing agents (e.g., DTT) are often included in enzymatic reactions to inhibit the oxidation of free sulfhydryl residues, and hence maintain protein activity.
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.[6]
2-Mercaptoethanol is considered a toxicant, 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.[7]