HEPES

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HEPES
Identifiers
CAS number7365-45-9 YesY
PubChem23831
ChemSpider22278 YesY
UNIIRWW266YE9I YesY
ChEBICHEBI:42334 YesY
RTECS numberTY2900000
Jmol-3D imagesImage 1
Properties
Molecular formulaC8H18N2O4S
Molar mass238.3 g mol−1
Appearancewhite crystalline powder
DensityNot applicable
Melting point

>234-238°C (453-457K)

Solubility in water40 g/100 ml (20°C)
Acidity (pKa)3 and 7.55
Hazards
MSDSExternal MSDS
R-phrasesR36, R37, R38.
S-phrasesS26, S36.
Main hazardsIrritant.
NFPA 704
NFPA 704.svg
0
1
1
Flash pointNon-flammable.
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
 
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HEPES
Identifiers
CAS number7365-45-9 YesY
PubChem23831
ChemSpider22278 YesY
UNIIRWW266YE9I YesY
ChEBICHEBI:42334 YesY
RTECS numberTY2900000
Jmol-3D imagesImage 1
Properties
Molecular formulaC8H18N2O4S
Molar mass238.3 g mol−1
Appearancewhite crystalline powder
DensityNot applicable
Melting point

>234-238°C (453-457K)

Solubility in water40 g/100 ml (20°C)
Acidity (pKa)3 and 7.55
Hazards
MSDSExternal MSDS
R-phrasesR36, R37, R38.
S-phrasesS26, S36.
Main hazardsIrritant.
NFPA 704
NFPA 704.svg
0
1
1
Flash pointNon-flammable.
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid ) is a zwitterionic organic chemical buffering agent; one of the twelve Good's buffers. HEPES is widely used in cell culture, largely because it is better at maintaining physiological pH despite changes in carbon dioxide concentration (produced by cellular respiration) when compared to bicarbonate buffers, which are also commonly used in cell culture. The dissociation of water decreases with falling temperature, but the dissociation constants (pK) of many other buffers do not change much with temperature. HEPES is like water in that its dissociation decreases as the temperature decreases. This makes HEPES a more effective buffering agent for maintaining enzyme structure and function at low temperatures.[1] Lepe-Zuniga et al. reported a phototoxicity of HEPES when exposed to ambient light by the production of hydrogen peroxide,[2][3] which is not a problem in bicarbonate-based cell culture buffers. It is therefore strongly advised to keep HEPES-containing solutions in darkness as much as possible. Fears that HEPES may serve as a nutrient source for aerobic bacteria have been shown to be unfounded.[citation needed]


"Good's buffers" such as HEPES are attributed with the following characteristics:

See also

References

  1. ^ Baicu SC, Taylor MJ. (2002). "Acid-base buffering in organ preservation solutions as a function of temperature: new parameters for comparing buffer capacity and efficiency". Cryobiology 45 (1): 33–48. doi:10.1016/S0011-2240(02)00104-9. PMID 12445548.
  2. ^ Lepe-Zuniga JL, Zigler JS, Gery I (October 1987). "Toxicity of light-exposed Hepes media". J. Immunol. Methods 103 (1): 145. doi:10.1016/0022-1759(87)90253-5. PMID 3655381. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+7722-84-1.
  3. ^ Zigler JS, Lepe-Zuniga JL, Vistica B, Gery I (May 1985). "Analysis of the cytotoxic effects of light-exposed HEPES-containing culture medium". In Vitro Cell. Dev. Biol. 21 (5): 282–7. doi:10.1007/BF02620943. PMID 4019356. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+7722-84-1.
  4. ^ http://www.invitrogen.com/site/us/en/home/Products-and-Services/Applications/Cell-Culture/Mammalian-Cell-Culture/reagents/hepes.html

External links

http://www.invitrogen.com/site/us/en/home/Products-and-Services/Applications/Cell-Culture/Mammalian-Cell-Culture/reagents/hepes.html