HEPES

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HEPES
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chemical structure of HEPES
Names
Preferred IUPAC name
2-[4-(2-Hydroxyethyl)piperazin-1-yl]ethane-1-sulfonic acid
Other names
HEPES
Identifiers
3D model (JSmol)
883043
ChEBI
ChemSpider
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EC Number
  • 230-907-9
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RTECS number
  • TL6809000
UNII
  • {{#property:P3117}}Lua error in Module:EditAtWikidata at line 29: attempt to index field 'wikibase' (a nil value).
  • 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) checkY
    Key: JKMHFZQWWAIEOD-UHFFFAOYSA-N checkY
  • 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
  • OCCN1CC[NH+](CCS(=O)([O-])=O)CC1
Properties
C8H18N2O4S
Molar mass 238.3012 g/mol
Appearance white crystalline powder
Density Not applicable
Melting point >234-238°C (453-457K)
40 g/100 ml (20°C)
Acidity (pKa) 3 (pKa1),
7.5 (pKa2)[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Eye Irritant
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319, H335
P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P312, P321, P322, P330, P332+P313, P337+P313, P362, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
1
0
1
Flash point Non-flammable
Safety data sheet (SDS) [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic sulfonic acid buffering agent. It is 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:

  • pKa1 (25 °C) = 3
  • pKa2 (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.

See also

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References

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