HEPES: Difference between revisions
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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. | ||
== Links == | |||
* [http://en.wikipedia.org/wiki/Buffer_solution Wikipedia: buffer solution] | |||
* [http://www.scribd.com/doc/12568914/Common-Buffers-Media-And-Stock-Solutions CP: common buffers] | |||
* [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 08:49, 2 November 2011
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.
