HEPES

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Buffers are typically 1 M, prepared by neutralizing HEPES with sodium hydroxide.  HEPES is essentially insoluble until it is neutralized.
Buffers are typically 1 M, prepared by neutralizing HEPES with sodium hydroxide.  HEPES is essentially insoluble until it is neutralized.
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== Links ==
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* [http://en.wikipedia.org/wiki/Buffer_solution Wikipedia: buffer solution]
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* [http://www.scribd.com/doc/12568914/Common-Buffers-Media-And-Stock-Solutions CP: common buffers]
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* [http://www.science.smith.edu/departments/Biochem/Biochem_353/Common_Buffers.html List of common buffers from Smith College]
[[Category:Material]] and [[Category:Buffers]]
[[Category:Material]] and [[Category:Buffers]]

Revision as of 10:49, 2 November 2011

Chemical structure of HEPES = N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid);aka 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS number: 7365-45-9
Chemical structure of HEPES = N-(2-hydroxyethyl)
piperazine-N’-
(2-ethanesulfonic acid);
aka 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS number: 7365-45-9

HEPES is a common buffering chemical similar to Tris in Tris-HCl buffers and phosphates in PBS. Buffers are used to keep the pH at a certain value and can "buffer" the addition of small amounts of acids/bases.

A Good buffer [Good'66 PMID 5942950, Good'74 PMID 4206745, Blanchard'84 PMID 6717292].


Property of HEPES

Stable pH vs. temperature, no primary amine groups, no metal chelation, near physiologic pH range. HEPES is often used to maintain protein solubility in biochemical experiments.

  • pKa at 25C of 7.55 (7.31 at 37C)
  • a second pKa at pH 3 is not of interest
  • usable buffering range of 6.8 to 8.2
  • molecular weight 238.3
  • ΔpKa/ΔT = -.014
  • HEPES contains tertiary amines, which are reactive under certain conditions.
  • Chemical formula: C8H18N2O4S

Buffers are typically 1 M, prepared by neutralizing HEPES with sodium hydroxide. HEPES is essentially insoluble until it is neutralized.

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