TBE buffer

TBE Buffer

TBE buffer is a commonly used buffer solution in molecular biology, particularly in the context of nucleic acid electrophoresis. It is an abbreviation for Tris/Borate/EDTA buffer, which is composed of three main components: Tris base, boric acid, and EDTA (ethylenediaminetetraacetic acid). TBE buffer is used to maintain a stable pH and provide ions that carry the current during the electrophoresis of DNA and RNA.

Composition

TBE buffer is typically prepared as a 10X stock solution, which can be diluted to 1X or 0.5X working concentrations. The standard 10X TBE buffer contains:

• 108 grams of Tris base
• 55 grams of boric acid
• 40 milliliters of 0.5 M EDTA (pH 8.0)

The final pH of the 10X solution is approximately 8.3. For use, the 10X stock is diluted with distilled water to the desired concentration.

Applications

TBE buffer is primarily used in agarose gel electrophoresis and polyacrylamide gel electrophoresis for the separation of nucleic acids. It is preferred over TAE buffer (Tris/Acetate/EDTA) in certain applications due to its higher buffering capacity and ability to maintain a stable pH over longer electrophoresis runs.

Advantages

• High buffering capacity: TBE buffer can maintain a stable pH during electrophoresis, which is crucial for the consistent migration of nucleic acids.
• Ion availability: The presence of borate ions helps in the conduction of electricity, facilitating the movement of DNA or RNA through the gel.

Disadvantages

• Inhibition of enzymatic reactions: Borate can inhibit some enzymatic reactions, such as PCR and ligation, which may require the use of TAE buffer instead.
• Precipitation: At high concentrations, TBE can lead to the precipitation of borate salts, which can interfere with electrophoresis.

Preparation

To prepare 1 liter of 10X TBE buffer:

1. Dissolve 108 grams of Tris base in approximately 800 milliliters of distilled water. 2. Add 55 grams of boric acid to the solution. 3. Add 40 milliliters of 0.5 M EDTA (pH 8.0). 4. Adjust the volume to 1 liter with distilled water. 5. Store the solution at room temperature.

Safety and Handling

While handling TBE buffer, it is important to wear appropriate personal protective equipment, such as gloves and goggles, to avoid skin and eye contact. Boric acid is a mild irritant, and EDTA can chelate metal ions, potentially affecting biological systems.

Also see

• TAE buffer
• Electrophoresis
• Agarose gel electrophoresis
• Polyacrylamide gel electrophoresis
• DNA ladder