Biological buffers are often used in biochemical research experiments and are of extremely important significance. They are a kind of conditioning fluid that can resist the influence of a small amount of strong acid and alkali from the outside and maintain the pH value basically unchanged. Among the commonly used biological buffers are Tris buffer solution, PBS buffer solution, CAPS buffer, MOPS buffer, TAPS buffer and EPPS buffer. This article will compare and introduce the most commonly used Tris buffer solution and PBS buffer solution from several aspects.
1. Buffer range
Tris is a weak base with a molecular formula of C4H11NO3, a molecular weight of 121.14, and a pKa of 8.1 at 25 °C. The effective buffer range of its buffer is between pH 7.0 and 9.2. The pH values commonly used in biochemical experiments are 6.8, 7.4, 8.0, and 8.8. Tris is widely used in the preparation of buffers in biochemistry and molecular biology experiments, and even has a tendency to exceed phosphate buffers.
Phosphate buffered saline (PBS) is a salt solution with phosphate as the pH buffer and sodium chloride as the osmotic pressure balance. Commonly used are sodium phosphate buffer and potassium phosphate buffer. Because of their secondary dissociation and a wide range of buffering pH values, they are the most widely used buffer solutions in biochemical research.
2. Configuration method
There are two ways to prepare Tris-HCl buffer: prepare Tris and HCl solutions separately, and then mix according to the volumes listed in the common table. However, because standard concentration of dilute hydrochloric acid is not easy to prepare, another method is commonly used: Take the configuration of Tris-HCl buffer as an example: first dissolve Tris base in 950 mL～970 mL deionized water, add HCl dropwise while stirring, and use The pH meter measures the pH value of the solution to the required pH value, and then adds water to it.
The preparation method of phosphate buffer solution: Weigh NaCl, KCl, KH2PO4 and K2HPO4, dissolve them in 800 mL of distilled water, adjust the pH of the solution to 7.4 with HCl, and finally add distilled water to make the volume to 1 L. It can be stored in a refrigerator at 4 ℃. It should be noted that the usual concentration refers to the concentration of all phosphates in the buffer solution, not the concentration of Na+ or K+. Na+ and K+ are only used to adjust the osmotic pressure. Potassium salt is better than sodium salt when configuring phosphate buffer solution. Sodium salt is not easy to dissolve at low temperature, while potassium salt has relatively higher solubility.
3. Field of Use
The Tris buffer solution forms a buffer system with glycine in the electrophoresis buffer to stabilize the pH; the Tris-HCl buffer system is used in the gel to stabilize the pH; it is widely used as a solvent for nucleic acids and proteins; the low ionic strength of the Tris buffer is also It can be used to form the intermediate fibers of nematodes; add EDTA to Tris hydrochloric acid buffer to make "TE buffer", which can be used for DNA stabilization and storage; change the pH-adjusting acid solution to acetic acid to obtain "TAE buffer" , Change to boric acid to get TBE buffer. These two buffers are often used in nucleic acid electrophoresis experiments.
Phosphate buffer solution Generally active biological preparations must be diluted with phosphate buffer solution. The reason is that it has a salt balance and a buffering effect that can adjust the appropriate pH value. Distilled water has no salt balance effect, which will destroy the structure and biological properties of biological proteins; physiological saline does not have the effect of adjusting pH, and it cannot ensure that it participates in biological reactions under optimal conditions for complete and active substances, so the use of PBS is Preferred. Of course, PBS is not a panacea. Some biologically active substances require relatively high conditions, and more ingredients need to be added to the balance buffer to maintain the best conditions to ensure that the biologically active substances maintain their most complete characteristics. Therefore, PBS is mainly used for cell experiments, and its buffer range is most suitable for neutral.
In the biochemical experiment, the buffer solution should be carefully selected, not only the buffer range of the buffer solution, but also the use environment of the buffer solution should be considered comprehensively. Hubei New Desheng Materials has been specializing in the production and development of biological buffers for many years. Desheng has an independent R&D team and has a wealth of practical experience in product development and production. At present, the biological buffers and other products produced by Desheng have been sold to many countries around the world, and they have been repurchased with praise, and have reached long-term cooperation with many foreign customers. If you are interested in understanding, you can call for consultation. Desheng welcomes your calls.
