What is the difference between Tris and HEPES buffer

Details:

In many biological and chemical experiments, buffer plays a very important role, because it can resist the action of a small amount of strong acids and bases and maintain the best pH value in the experimental system. There are many kinds of biological buffers, among which Zui commonly used are Tris buffer and HEPES buffer. Many people do not know the difference between them and where they are applicable Let's compare and summarize.

Biological buffer

HEPES buffer: HEPES belongs to the good's buffer series. It is widely used in a variety of biochemical reactions and cell culture media. The effective buffer range is 6.8-8.2. It is usually used for organelles and proteins with variability and pH sensitivity, as well as biochemical diagnostic kits, DNA / RNA extraction kits and PCR diagnostic kits. It has limited influence on biochemical reaction, can resist chemical action and enzymatic hydrolysis, and does not produce complex or precipitation with metal ions.

Preparation method: HEPES can be directly added to the prepared culture medium according to the required concentration, and then filtered and sterilized. Add 2.38g HEPES to every 1000ml culture medium, adjust the pH to 7.2 with LN NaOH after dissolution, and use after filtration and sterilization. At this time, the concentration of HEPES is 10   mmol/L。

Tris buffer: Tris is weakly alkaline, pKa is 8.1 at 25, and the effective buffer is 7.0~9.2. It is often used as buffer in electrophoresis and gel experiments, or as a solvent for nucleic acids and proteins. Only Tris HCl buffer system can prepare buffers with pH ranging from acidic to alkaline, and can form a variety of buffer systems with other substances. Its derived buffers te, TAE and tbe are often used for DNA stability, storage and extraction. It has little interference to the biochemical process and does not precipitate with calcium, magnesium ions and heavy metal ions. Affected by the solution concentration, it is diluted ten times and the pH change is greater than 0.1.

Preparation method:

Take 1L 0.1mol/l Tris HCl buffer as an example: dissolve 12.11g Tris alkali in 950 ~ 970ml deionized water, stir and drop 4N HCl to determine the pH value of the solution, and then add water to dissolve to 1L.

In conclusion, HEPES and Tris buffers are different in buffer range, application field, characteristics and preparation methods. In the specific experiment, the experimental conditions should be carefully analyzed and the appropriate buffer should be selected.