What is the difference between biological buffer Tris and HEPES

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 acid and alkali, and maintain the best pH value in the experimental system. There are many kinds of biological buffers, among which Tris buffer and HEPES buffer are commonly used. Many people don't know the difference between them and where they are suitable for Let's make a comparison and summary.

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, with an effective buffer range of 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 is resistant to chemical action and enzymatic hydrolysis, and does not produce complexes or precipitates with metal ions.

Preparation method: HEPES can be directly added into the prepared culture medium according to the required concentration, and then filtered for sterilization. 2.38g HEPES can be added into every 1000ml culture medium, and adjusted to pH 7.2 with LN NaOH after dissolving, and then filtered for 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 buffer solutions with pH ranging from acidic to alkaline, and can form a variety of buffer systems with other substances. The derived buffers te, TAE and tbe are often used for DNA stability, storage and extraction. It does not precipitate with calcium, magnesium and heavy metal ions. It is affected by the concentration of the solution, diluted ten times, and pH changes more 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, add 4N HCl to measure the pH value of the solution under stirring, 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, we should carefully analyze the experimental conditions and choose the appropriate buffer.