Hepes

HEPES
Names
	Preferred IUPAC name 2-[4-(2-Hydroxyethyl)piperazin-1-yl]ethane-1-sulfonic acid
	Other names HEPES
Identifiers
CAS Number	7365-45-9 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	883043
ChEBI	CHEBI:42334 ;
ChemSpider	22278 ;
EC Number	230-907-9;
PubChem CID	23831;
RTECS number	TL6809000;
UNII	RWW266YE9I ;
	InChI InChI=1S/C8H18N2O4S/c11-7-5-9-1-3-10(4-2-9)6-8-15(12,13)14/h11H,1-8H2,(H,12,13,14) Key: JKMHFZQWWAIEOD-UHFFFAOYSA-N ; InChI=1/C8H18N2O4S/c11-7-5-9-1-3-10(4-2-9)6-8-15(12,13)14/h11H,1-8H2,(H,12,13,14) Key: JKMHFZQWWAIEOD-UHFFFAOYAC;
	SMILES OCCN1CC[NH+](CCS(=O)([O-])=O)CC1;
Properties
Chemical formula	C8H18N2O4S
Molar mass	238.3012 g/mol
Appearance	white crystalline powder
Density	Not applicable
Melting point	>234-238°C (453-457K)
Solubility in water	40 g/100 ml (20°C)
Acidity (pKa)	3 (pKa1),; 7.5 (pKa2)
Hazards
Main hazards	Eye Irritant
Safety data sheet	[1]
GHS pictograms
GHS Signal word	Warning
GHS hazard statements	H315, H319, H335
GHS precautionary statements	P261, P264, P270, P271, P280, P301+312, P302+352, P304+312, P304+340, P305+351+338, P312, P321, P322, P330, P332+313, P337+313, P362, P363, P403+233, P405, P501
NFPA 704 (fire diamond)	0 1 1
Flash point	Non-flammable
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	verify (what is ?)
	Infobox references

HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic sulfonic acid buffering agent; one of the twenty 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 aerobic respiration) when compared to bicarbonate buffers, which are also commonly used in cell culture. ^[2] Lepe-Zuniga et al. reported an unwanted photochemical process wherein HEPES catalyzes a reaction with riboflavin when exposed to ambient light to produce hydrogen peroxide.^[3]^[4] This is not a problem in bicarbonate-based cell culture buffers. It is therefore strongly advised to keep solutions containing both HEPES and riboflavin in darkness as much as possible to prevent oxidation.

HEPES has the following characteristics:

pK_a1 (25 °C) = 3
pK_a2 (25 °C) = 7.5
Useful pH range = 2.5 to 3.5 or 6.8 to 8.2

HEPES has negligible metal ion binding,^[5] making it a good choice as a buffer for enzymes which might be inhibited by metal chelation.

References

↑ "Phase Coexistence in Single-Lipid Membranes Induced by Buffering Agents". Langmuir 30 (33): 9880-9885. 2014. doi:10.1021/la5018938.
↑ "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. 2002. doi:10.1016/S0011-2240(02)00104-9. PMID 12445548.
↑ "Toxicity of light-exposed Hepes media". Journal of Immunological Methods 103 (1): 145. October 1987. 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.
↑ "Analysis of the cytotoxic effects of light-exposed HEPES-containing culture medium". In Vitro Cellular & Developmental Biology 21 (5): 282–7. May 1985. doi:10.1007/BF02620943. PMID 4019356. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+7722-84-1.
↑ "Hopax Fine Chemicals - Biological buffers and their interactions with metal ions". https://www.hopaxfc.com/en/blog/biological-buffers-and-their-interactions-with-metal-ions.

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Original source: https://en.wikipedia.org/wiki/HEPES. Read more

[1] "Phase Coexistence in Single-Lipid Membranes Induced by Buffering Agents". Langmuir 30 (33): 9880-9885. 2014. doi:10.1021/la5018938.

[2] "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. 2002. doi:10.1016/S0011-2240(02)00104-9. PMID 12445548.

[pmid3655381-3] "Toxicity of light-exposed Hepes media". Journal of Immunological Methods 103 (1): 145. October 1987. 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.

[pmid4019356-4] "Analysis of the cytotoxic effects of light-exposed HEPES-containing culture medium". In Vitro Cellular & Developmental Biology 21 (5): 282–7. May 1985. doi:10.1007/BF02620943. PMID 4019356. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+7722-84-1.

[5] "Hopax Fine Chemicals - Biological buffers and their interactions with metal ions". https://www.hopaxfc.com/en/blog/biological-buffers-and-their-interactions-with-metal-ions.

Hepes

See also

References