Biological buffer is a solution that can keep the pH of the solution relatively stable when a small amount of acid or alkali is added. Most cells can only move in a narrow pH range, and a buffer system is required to resist the occurrence of metabolic processes. pH changes. In biochemical research work, buffer solutions are often used to maintain the pH of the experimental system. There are many types of biological buffers and a wide range of uses, and the appropriate system needs to be selected according to the actual application.
1. PB buffer (phosphate buffer)
Phosphate buffer, also known as PB buffer, is a widely used buffer. Due to its secondary dissociation effect, the buffer pH range is wide, and acidic, alkaline and neutral buffers with different pH values ??can be configured.
Advantages of PB buffer:
①Easy to be formulated into various concentrations;
②Wide range of pH value;
③ pH is less affected by temperature.
Disadvantages of PB buffer:
①It is easy to form precipitation with common calcium, magnesium and heavy metal ions;
②Inhibit certain biochemical processes.
2.Tris buffer
Tris buffer has a wide range of applications in biochemical research. It is a weak base and is usually used in the "neutral" range.
Advantages of Tris buffer:
①Because the Tris base is relatively alkaline, this buffer system can be used to prepare buffers with a wide range of pH values ??ranging from acidic to alkaline;
②It has little interference to the biochemical process, and does not precipitate with calcium, magnesium ions and heavy metal ions.
Disadvantages of Tris buffer:
① The pH of the buffer is greatly affected by the concentration of the solution. The buffer is diluted ten times, and the change in pH is greater than 0.1;
②The temperature effect is large, and the temperature change has a great influence on the pH value of the buffer, so it must be prepared at the use temperature, and the Tris-HCl buffer prepared at room temperature cannot be used at 0°C to 4°C;
③It is easy to absorb CO2 in the air, so the prepared buffer should be tightly sealed;
④It has a certain interference effect on some pH electrodes, so an electrode compatible with Tris solution should be used.
3. Glycine buffer
Glycine buffer has a wide pH range and a wide range of applications. The pH value ranges from 2.0 to 11.0. The most common systems and pH ranges are shown in the table below:
Glycine buffer solution pH range
Glycine-HCl 2.0~5.0
Glycine-NaOH 8.0~11.0
Glycine-Tris 8.0~11.0
Glycinamide buffer solution 7.8~8.8
Glycylglycine buffer 8.0~9.0
The advantage of glycine buffer: It provides a closer natural environment for cell components and various extracts.
Disadvantages of glycine buffer: similar to phosphate buffer system; interfere with certain biochemical reaction processes, such as metabolic processes.