TAE buffer

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.^[1] It is made up of Tris-acetate buffer, usually at pH 8.3, and EDTA, which sequesters divalent cations. TAE has a lower buffer capacity than TBE and can easily become exhausted, but linear, double stranded DNA runs faster in TAE.

Previously, Brody & Kern simplified electrophoretic buffers by substituting TBE and TAE buffers for a more efficient and inexpensive conductive media in gel systems.^[2]

Uses

TAE (Tris-acetate-EDTA) buffer is used as both a running buffer and in agarose gels.^[3] Its use in denaturing gradient gel electrophoresis methods for broad-range mutation analysis has also been described.^[4] TAE has been used at various concentrations to study the mobility of DNA in solution with and without sodium chloride.^[5] However, high concentrations of sodium chloride (and many other salts) in a DNA sample retard its mobility. This may lead to incorrect interpretations of the resulting DNA banding pattern.

Preparation

TAE buffer is commonly prepared as a 50× stock solution for laboratory use. A 50× stock solution can be prepared by dissolving 242 g Tris base in water, adding 57.1 ml glacial acetic acid, and 100 ml of 500 mM EDTA (pH 8.0) solution, and bringing the final volume up to 1 litre. This stock solution can be diluted 49:1 with water to make a 1× working solution. This 1× solution will contain 40 mM Tris, 20 mM acetic acid, and 1 mM EDTA.

No.	Name	Per 1 mole	50x solution	50×	1× solution	1X
1	Tris base	121.1 g/L	2 M	242.2 g/L	40 mM	4.844 g/L
2	acetic acid	57.1 ml/L	1 M	57.1 ml/L	20 mM	1.21 ml/L
3	EDTA disodium salt dihydrate	372.24 g/L	50 mM	18.612 g/L	1 mM	0.372 g/L

2 M = 2000 mM so 2000 mM /50 = 40 mM for 1×.
1M = 1000 mM so 1000 mM /50 = 20 mM for 1×.
50 mM /50 = 1 mM for 1×.

First of all, these ingredients should be dissolved in 500 ml, then made up to 1000 ml.
Note: EDTA will take more time to dissolve, so while dissolving EDTA use magnetic stirrer (few amounts of EDTA in 3 or 4 times).

A step-by-step recipe of the preparation method for 50× TAE buffer is available on protocols.io.^[6]

See also

• TBE buffer
• LB buffer