TAE

TAE buffer is a buffer solution containing a mixture of Tris base, acetic acid and EDTA. In molecular biology it is used in agarose electrophoresis typically for the separation of nucleic acids such as DNA and RNA. It is made up of Tris-acetate buffer, usually at pH 8.0, and EDTA, which sequesters divalent cationic metals.

Composition

TAE buffer is composed of 40 mM Tris, which acts as the buffering agent, 20 mM acetic acid, which provides the necessary pH, and 1 mM EDTA. The EDTA acts as a chelating agent for divalent cations, particularly magnesium (Mg2+), which is necessary for nuclease activity.

Usage

TAE buffer is used in molecular biology for tasks such as DNA electrophoresis. It provides the ions that carry the current through the gel and maintains the pH at a level where the DNA will migrate towards the positive electrode. The EDTA in the buffer chelates divalent cations, which inhibits enzymes that degrade DNA.

Preparation

To prepare a 50X stock solution of TAE buffer, dissolve 242 g of Tris base in 750 ml of water. Add 57.1 ml of glacial acetic acid and 100 ml of 0.5 M EDTA (pH 8.0). Adjust the final volume to 1 liter with water. This stock solution can be stored at room temperature and diluted to 1X before use.

See also

• TBE buffer
• Agarose gel electrophoresis
• Molecular biology

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