TAE buffer

TAE Buffer

TAE buffer, an acronym for Tris-acetate-EDTA buffer, is a commonly used buffer solution in molecular biology, particularly in the field of nucleic acid electrophoresis. It is primarily used for the separation of DNA and RNA fragments by agarose gel electrophoresis.

Composition

TAE buffer is composed of three main components:

• Tris (tris(hydroxymethyl)aminomethane): A common biological buffer that maintains a stable pH environment. In TAE buffer, Tris is used to maintain the pH around 8.0.
• Acetate: Provides the ionic strength necessary for the electrophoresis process. Acetate ions help in conducting the electric current through the gel.
• EDTA (Ethylenediaminetetraacetic acid): A chelating agent that sequesters divalent metal ions such as Mg²⁺ and Ca²⁺. This is important because these ions can act as cofactors for nucleases, which could degrade the DNA or RNA.

Preparation

TAE buffer is typically prepared as a 50x stock solution, which can be diluted to a 1x working solution for use in electrophoresis. The 50x stock solution is made by dissolving the following components in distilled water:

• 242 g of Tris base
• 57.1 mL of glacial acetic acid
• 100 mL of 0.5 M EDTA (pH 8.0)

The final volume is adjusted to 1 liter with distilled water. For use, the stock solution is diluted 1:50 with distilled water to make a 1x TAE buffer solution.

Applications

TAE buffer is widely used in:

• Agarose gel electrophoresis: TAE buffer is preferred for the separation of large DNA fragments (>12 kb) because it provides better resolution for larger fragments compared to other buffers like TBE buffer.
• DNA extraction and purification: TAE buffer can be used in various steps of DNA extraction protocols to maintain the integrity of the DNA.

Advantages and Disadvantages

Advantages

• Low ionic strength: TAE buffer has a lower ionic strength compared to TBE buffer, which results in less heat generation during electrophoresis, reducing the risk of gel melting.
• Better resolution for large DNA fragments: TAE buffer provides better resolution for larger DNA fragments, making it suitable for certain applications.

Disadvantages

• Lower buffering capacity: TAE buffer has a lower buffering capacity than TBE buffer, which means the pH can change more easily during electrophoresis, potentially affecting the results.
• Not ideal for small DNA fragments: For smaller DNA fragments, TBE buffer might be preferred due to its higher buffering capacity and better resolution for small fragments.

Also see

• TBE buffer
• Agarose gel electrophoresis
• DNA electrophoresis
• Buffer solution