HEPES: Difference between revisions
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N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid); 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS NUMBER: 7365-45-9 | N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid); 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS NUMBER: 7365-45-9 | ||
A Good buffer <cite>Good66</cite><cite>Good74</cite><cite>Blanchard84</cite>. Stable pH vs. temperature, no amine groups, no metal chelation, near physiologic pH range. | A Good buffer <cite>Good66</cite><cite>Good74</cite><cite>Blanchard84</cite>. Stable pH vs. temperature, no primary amine groups, no metal chelation, near physiologic pH range. | ||
* pK<sub>a</sub> at 25C of 7.55 (7.31 at 37C) | * pK<sub>a</sub> at 25C of 7.55 (7.31 at 37C) | ||
| Line 8: | Line 8: | ||
* molecular weight 238.3 | * molecular weight 238.3 | ||
* ΔpK<sub>a</sub>/ΔT = -.014 | * ΔpK<sub>a</sub>/ΔT = -.014 | ||
*HEPES contains tertiary amines, which are reactive under certain conditions. See its structure in the [http://www.sigmaaldrich.com/catalog/search/ProductDetail/SIGMA/H3375 Sigma catalog]. | |||
*Chemical formula: C<sub>8</sub>H<sub>18</sub>N<sub>2</sub>O<sub>4</sub>S | |||
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. | ||
Revision as of 08:52, 5 May 2006
N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid); 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS NUMBER: 7365-45-9
A Good buffer [1][2][3]. Stable pH vs. temperature, no primary amine groups, no metal chelation, near physiologic pH range.
- 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. See its structure in the Sigma catalog.
- Chemical formula: C8H18N2O4S
Buffers are typically 1 M, prepared by neutralizing HEPES with sodium hydroxide. HEPES is essentially insoluble until it is neutralized.
- Good NE, Winget GD, Winter W, Connolly TN, Izawa S, and Singh RM. Hydrogen ion buffers for biological research. Biochemistry. 1966 Feb;5(2):467-77. DOI:10.1021/bi00866a011 |
- Good NE and Izawa S. Hydrogen ion buffers. Methods Enzymol. 1972;24:53-68. DOI:10.1016/0076-6879(72)24054-x |
- Blanchard JS. Buffers for enzymes. Methods Enzymol. 1984;104:404-14. DOI:10.1016/s0076-6879(84)04107-0 |
