The diffirent of PIPES and HEPES.

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Good's buffer is a kind of buffer system specially designed for life science research. It does not participate in or interfere with biochemical processes. Here we introduce two commonly used Good's buffers, PIPES and HEPES.


The pH buffer range of PIPES is 6.1-7.5, insoluble in water and soluble in NaOH solution. PIPES is different from the buffer containing bis (2-hydroxyethyl) amino groups (such as Bis-tris, Bicine), which can not form stable complexes with most metal ions. It is suitable for buffer containing metal ions in solution system. According to previous studies, PIPES can be used to purify tubulin by using cellulose phosphate chromatography, and to purify recombinant GTP binding protein ARF1 and ARF2 by gel filtration as a buffer to crystallize ketoenzyme from E. coli. In addition, because PIPES can form free radicals, it is not suitable for redox system. Low concentration of PIPES buffer should be used in cation exchange chromatography because PIPES has relatively high ionic strength and its pKa value is concentration dependent.


The pH buffer range of HEPES is 6.8-8.2, which is soluble in water and does not form stable complexes with metal ions. In most cases, it does not interfere with biochemical processes. HEPES is often used in cell culture media of various types of organisms. In protein research, PIPES is often used as a component and wash of binding buffer in cation exchange chromatography. In DNA research, PIPES is used as buffer for calcium phosphate and DNA precipitate formation system, as well as for AFM and electroporation experiments. In addition, HEPES interferes with the reaction between DNA and restriction enzymes, and is not suitable for Lowry's method to determine protein content.

In summary, PIPES and HEPS belong to Good's buffer. They can not form stable complexes with metal ions and are suitable for solution systems containing metal ions. But there are some differences between them. In terms of solubility, PIPES is insoluble in water, while HEPES has good water solubility; in terms of buffer range, PIPES is acidic to neutral, HEPES is neutral to alkaline, which is mainly due to the structural differences between them. PIPES has two sulfonic groups, and HEPES contains one sulfonic group and one alkaline group. Hydroxyl group. In addition, PIPES and HEPES have some limitations in the application of some systems. Therefore, when choosing the buffer, we need to consider the suitability of the experimental system and the difference of their properties.