HEPES

N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid); 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS NUMBER: 7365-45-9

A Good buffer Good66 Good74  Blanchard84. 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
 * &Delta;pKa/&Delta;T = -.014
 * HEPES contains tertiary amines, which are reactive under certain conditions.
 * See the structure of HEPES.
 * Chemical formula: C8H18N2O4S

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


 * 1) Good66 pmid=5942950
 * 2) Good74 pmid=4206745
 * 3) Blanchard84 pmid=6717292

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