The similarities and differences of biological buffer CAPS and CHES

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N-Cyclohexyl-3-aminopropanesulfonic, abbreviated as CAPS, Chinese name is 3-cyclohexylaminopropanesulfonic acid; 2-(Cyclohexylamino)ethanesulfonic acid, abbreviated as CHES, Chinese name is 2-cyclohexylaminoethanesulfonic acid, both biochemical and molecular Buffer reagents commonly used in experiments. Judging from the Chinese names, you might think that comparing them is very similar. Let's take a look at the similarities and differences between them.

Similarities between CAPS and CHES

Both CAPS (CAS 1135-40-6) and CHES are zwitterionic buffers, and their buffering range is in the alkaline range, which is higher than the commonly used physiological range. Although they are not introduced by Good et al., they are sometimes referred to as Good's Buffers. None of them complexes with metal ions.

The structural differences between CAPS and CHES

The molecular formulas of CAPS and CHES are C9H19NO3S and C8H17NO3S, respectively. They have the same cyclohexylamino structure, but the carbon chain length is different, as shown in the figure below:

CHES has a pKa value of 9.5 at 25°C and a pH buffer range of 8.6 to 10.0; CAPS has a pKa value of 10.4 at 25°C and a buffer range of 9.7 to 11.1. The longer sulfonic acid carbon chain makes it more basic than CHES.

Differences in the application of CAPS and CHES

CAPS application:

(1) Transfer buffer for diffusion blotting and electro-blotting; binding buffer and eluent for cation exchange chromatography; running buffer for capillary electrophoresis; buffer for enzyme assay

(2) Effective crystallization solutions of various proteins;

(3) Support alkaline phosphatase activity and inhibit the growth of Aeromonas. pH value 10.5;

(4) Suitable for the detection of bicinchoninic acid (BCA).

Application of CHES:

(1) Enzymatic reaction buffer;

(2) Various types of capillary electrophoresis samples and running buffers;

(3) It has high affinity to the iodoacetic acid binding site of liver alcohol dehydrogenase, and protects the enzyme from being inactivated by iodoacetic acid;

(4) Compared with other buffers, it has the largest phosphodiesterase activity;

(5) Inhibit the vigor of Micrococcus luteus at pH 9.5.

In summary, CAPS and CHES have certain similarities in structure and properties. For example, the buffer range is alkaline, both are zwitterionic buffers, and do not react with metal ions, etc., but there are also many differences in applications. , CAPS is more alkaline than CHES, and the applicable experiments are also different. Therefore, it is necessary to analyze carefully before use and choose the most suitable buffer. Desheng is a direct manufacturer of buffering agents. TRIS, CAPS and CHES have always had stable cooperative customers. The reason is that Desheng recognizes Desheng’s quality and service. Now Desheng’s products are slowly going abroad, and more and more With internationalization, Desheng will be stronger in the future.