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What are the biological buffers and how should they be selected
Biobuffer is a kind of solution that can keep the pH value of solution relatively stable when adding a small amount of acid or alkali. Most cells can only operate in a very narrow range of pH. A buffer system is needed to resist the change of pH during metabolism. Buffer solution is often used to maintain the acidity and basicity of the experimental system in biochemical research.
Let's look at the commonly used biological buffers and their characteristics:
NO 1 Phosphate buffer
Phosphate buffer is the most widely used buffer. Due to its secondary dissociation, the buffer has a wide range of pH values and can be configured with acidic, alkaline and neutral buffers with different pH values:
NaH2PO4 or KH2PO4 can be directly used to prepare acidic buffer with pH ranging from 1 to 5.
Na2HPO4 or K2HPO4 can be used directly in alkaline buffer with pH ranging from 9 to 12.
The neutral buffer contains the same amount of NaH2PO4 and Na2HPO4 or the same amount of KH2PO4 and K2HPO4 solutions, and the pH value is 5.5-8.5.
Advantages: 1) Easy preparation of various concentrations; 2) wide range of pH value; 3) pH is less affected by temperature;
Disadvantages: 1) easy to precipitate with common calcium, magnesium and heavy metal ions; 2) inhibit some biochemical processes;
NO 2 Tris Buffer
Tris buffer has been widely used in biochemical research. It is a weak base, usually used in the "neutral" range. Tris-HCl buffer: pH = 7.5-8.5; triphosphate buffer: pH = 5.0-9.0.
In addition to TRIS-hcl, TRIS has a variety of derivative buffers:
TBS = Tris-HCl + NaCl + KCl, commonly used to clean immunostained tissues or Western blotting membranes;
TBST = Tris-HCl+NaCl+tween20, a membrane buffer commonly used in Western Blotting;
TE = Tris-HCl + EDTA, which has a protective effect on DNA bases, is commonly used for DNA stabilization and storage.
TAE = Tris base + acetic acid + EDTA is a buffer system widely used in short fragment DNA electrophoresis.
TBE = tribasic + boric acid + EDTA, suitable for long-term DNA electrophoresis, has a good separation effect for small fragments.
Advantages: 1) Because Tris base is alkaline, it can only be used to prepare a buffer with a wide range of pH values ranging from acidic to alkaline. 2) It has little interference with biochemical processes and does not precipitate with calcium, magnesium and heavy metal ions.
Disadvantages: First, the pH value of buffer is greatly affected by the concentration of solution, the buffer is diluted ten times, and the change of pH value is greater than 0.1; Second, the temperature effect is great, and the change of temperature has a great influence on the pH value of buffer, so it must be prepared at the use temperature. Tris-HCl buffer prepared at room temperature can not be used at 0-4 C. 3. Easy to absorb CO2 in the air, so the buffer should be sealed tightly. (4) The buffer can interfere with some pH electrodes, so the electrodes compatible with Tris solution should be used.
NO 3 Good's Buffer
In the mid-1960s, N.E. Good had to use artificial design and synthesis methods to find specific buffer systems for life sciences research, since the general buffer systems were not suitable for biochemical laboratories. These buffer systems all had the following characteristics:
1. pKa is between 6 and 8; 2. It has high solubility in aqueous solution; 3. Salt effect is very small; 4. It is not easy to be transported through cell membrane; 5. It is not easy to be affected by temperature, ion composition, concentration and other factors; 6. It does not form a mismatch with metal ions, or the mismatch does not precipitate and interfere with biological activity; 7. Its chemical properties are stable.
Advantages: It does not participate in or interfere with the biochemical reaction process and has no inhibitory effect on enzymatic chemical reaction, so it is specially used in the research of organelles and highly changeable, pH-sensitive proteins and enzymes.
Disadvantages: Biuret and Lowry methods for protein content determination are not applicable because they darken the color of blank tubes.
NO 4 Glycine buffer
Glycine buffer has a wide range of pH value and wide application. The range of pH value is from 2.0 to 11.0.
Advantages: Provide a closer natural environment for cell components and extracts.
Disadvantages: Similar to phosphate buffer systems; interferes with certain biochemical processes, such as metabolic processes.
Desheng Biochemical Technology was founded in 2005. After years of innovation and development, Desheng Biochemical Technology has become a leading company with "in vitro diagnostic reagent raw materials", "biological buffers" and "blood vessel extracting additives". It integrates R&D, production and sales, and serves many manufacturers at home and abroad.