Buffer is a type of substance that maintains the pH of the reaction system, usually composed of weak acids, weak bases and their salts or amphoteric substances, such as CO2 in photosynthesis, bicarbonate in human plasma, etc. are substances with buffering capacity, which is necessary for cellular metabolic reactions. In the field of biochemical detection, the most commonly used are Tris buffer and phosphate buffer, and there are certain differences between the two.
1. Buffer range
The buffering range of Tris buffer is 5.0~9.2, there are differences according to different acids of Tris.
Commonly used pH in biochemical tests are 6.8, 7.4, 8.0, 8.8. Tris buffers are used more and more in biochemical research, and there is a tendency to exceed phosphate buffers. For example, Tris buffers have been used in SDS-polyacrylamide gel electrophoresis, and phosphates are rarely used.
The buffer range of phosphate PBS buffer is 1~12, adjusted according to the ratio of different phosphate acid salts.
Phosphate is one of the most traditional and extensive buffers in biochemistry. Phosphoric acid has two acid salts. They are second-order dissociation and have two dissociation constants. Therefore, the pH range of the buffers they make is very wide. Generally, potassium salt is better than sodium salt, and its solubility is high. SDS-polyacrylamide gel electrophoresis buffer can not use potassium salt, potassium salt of SDS will precipitate.
2. Application areas
Tris is a tromethamine as an amino buffer base that does not contain sodium. It does not bring sodium and potassium ions into the system and does not affect the osmotic pressure. It can also be added with saline to adjust the salt balance if necessary. It has little effect on the biochemical process, and it does not form precipitates with calcium, enzymes and heavy metal ions, and does not affect the activities of kinases, phosphatases, dehydrogenases and other enzymes. Usually used for DNA, RNA and protein related experiments, commonly used buffer systems are: Tris-HCl buffer, TBS buffer, TE buffer, TAE buffer, TBE buffer, Tris glycine buffer, Tris phosphate buffer, etc. It should be noted that the pH value of Tris is greatly affected by temperature, and it is necessary to control the temperature; the Tris solution is alkaline, it will absorb CO2, and pay attention to sealing.
Although phosphate buffers have a wider buffering range, the buffering capacity above pH 7.5 is smaller. Tris itself is better when it is alkaline. Phosphate itself can dissociate cations and has a salt balance effect, which will not break the organism. Protein structure and biological characteristics, phosphate PBS buffer is usually used for cell experiments. However, precipitation with calcium, magnesium ions and heavy metal ions will also inhibit the activity of certain enzymes.
Nowadays, the application of Tris buffer is more and more, there is a tendency to exceed phosphate buffer, Desheng Technology is also focusing on the development of Tris buffer related applications. However, it is recommended that you select the best biological buffer according to the reagent requirements of the experiment.
