2-Mercaptoethanol

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2-Mercaptoethanol

IUPAC name[hide]

2-Sulfanylethan-1-ol[citation needed]

Other names[hide]

2-Hydroxy-1-ethanethiol[citation needed]

β-Mercaptoethanol[citation needed]

Thioglycol[citation needed]

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 SMILES

[show]

InChI

[show]

Properties

Molecular formula C

2H

6SO

−1

Molar mass 78.133 g mol

−3

Density 1.114 g cm

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 P260, P273, P280, P284,P301+310, P302+350

statements

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

1,2-Ethanedithiol

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Except where noted otherwise, data are given for materials in their standard

state (at 25 °C, 100 kPa)

Infobox references

2-Mercaptoethanol (also β-mercaptoethanol, BME, 2BME, 2-ME or β-met) is the chemical

compound with the formula HOCH2CH2SH. 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.

 1 Preparation

 2 Reactions

 3 Applications

o 3.1 Reducing proteins

o 3.2 Preventing protein oxidation

o 3.3 Denaturing ribonucleases

 4 Safety

 5 References Preparation

2-Mercaptoethanol may be prepared by the action of hydrogen sulfide on ethylene oxide:[1]

Reactions

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

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.[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 used 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.

Although 2-mercaptoethanol has a higher volatility than DTT, it is more stable: 2- mercaptoethanol's half-life is more than 100 hours at pH 6.5 and 4 hours at pH 8.5; DTT's half-life is 40 hours at pH 6.5 and 1.5 hours at pH 8.5.[5][6] Preventing protein oxidation

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. It is used in several enzyme assays as a standard buffer.[7] 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.[8] Safety

2-Mercaptoethanol is considered toxic, 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.[9]

References

^ 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.

1. ^ "1,3-Dithiolanes, 1,3-Dithianes". Organic Chemistry Portal. Archived from

the original on 17 May 2008. Retrieved 27 May 2008.

2. ^ "2-Mercaptoethanol". Chemicalland21.com. Archived from the original on

5 October 2006. Retrieved 8 October 2006.

3. ^ Aitken CE, Marshall RA, Puglisi JD (2008). "An oxygen scavenging

system for improvement of dye stability in single-molecule fluorescence experiments". Biophys J 94 (5): 1826–

35.doi:10.1529/biophysj.107.117689. PMC 2242739. PMID 17921203.

4. ^ Yeh, J. I. "Additives and microcalorimetric approaches for optimization of

crystallization" in Protein Crystallization, 2nd Edition (Ed: T. Bergfors) 2009, International University Line, La Jolla, CA. ISBN 978-0-9720774-4-6.

5. ^ Stevens R., Stevens L., Price N.C. (1983). "The Stabilities of Various

Thiol Compounds used in Protein Purifications". Biochemical Education 11 (2): 70. doi:10.1016/0307-4412(83)90048-1.

6. ^ Verduyn, C., van Kleef, R., Frank, J., Schreuder, H., van Dijken, J.P. and

Scheffers, W.A. (1985) Biochem. J. 226, 669-677. 7. ^ Nelson, David R.; Lehninger, Albert L; Cox, Michael (2005). Lehninger

principles of biochemistry. New York: W.H. Freeman. p. 148. ISBN 0-7167- 4339-6.

8. ^ "Material Safety Data Sheet". JT Baker. Retrieved 31 July 2011.