TAE buffer (Tris-acetate-EDTA)
Introduction
Tris-acetate-EDTA (TAE) is one of the most commonly used buffers for DNA and RNA agarose electrophoresis. It has a lower buffering capacity compared to TBE (Tris-borate-EDTA) but runs nucleic acids faster, hence became the first choice. The composition that is currently being used is developed by the contribution of different research groups in the early 1970s. TAE is commonly prepared as a 50X solution with pH 8.5.
Applications
Commonly used buffer for DNA and RNA based methods using Agarose electrophoresis such as.
- Restriction enzyme mapping.
- Plasmid map confirmation.
- To check the PCR (polymerase chain reaction)
product and separation of correct size amplicons. - Quantification of DNA mixture (electrophoresis resolves DNA mixture and intensity of
bands can be used of quantification).
Composition
| Reagent | Molecular weight | 1X TAE molarity | 50X TAE molarity | Add for 500ml of 50X TAE | Add for 1L of 50X TAE |
|---|---|---|---|---|---|
| Tris Base | 121.14 g/mol | 40 mM | 2 M | 121.1 g | 242.2 g |
| Acetic Acid (glacial) | 60.5 g/mol | 20 mM | 1 M | 30.25 ml | 60.5 ml |
| EDTA Sodium salt dihydrate | 372.24 g/mol | 1 mM | 50 mM | 9.3 g | 18.6 g |
Table 1.
Glacial acetic acid: Glacial is a fancy term used to mention acetic acid which has very less amount of water in it (consider less than 1% for the sake of discussion). Vinegar is also acetic acid but not glacial since it contains water ranging from 80-95%.
pH
No need to adjust the pH of the buffer. Adding the components in the specified quantities brings pH close to 8.5.
Preparation
- Add the components in half the volume of ddH2O intended for the volume.
- Put the beaker in magnetic stirrer with a magnetic pellet.
- EDTA dissolves very slowly, so have a cup of coffee and relax.
- Once all components dissolved, make up the volume with ddH2O intended for.
- Now you have 50X TAE.
- For making 1X TAE from 50X stock, add one part 50X TAE to 49 parts of ddH2O.
Storage
Store the TAE buffer at room temperature.