TAE buffer (Tris-acetate-EDTA)

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    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).

    pH

    No need to adjust the pH of the buffer. Adding the components in the specified quantities brings pH close to 8.5.

    Composition

    ReagentMolecular weight1X TAE molarity50X TAE molarityAdd for 500ml of 50X TAEAdd for 1L of 50X TAE
    Tris Base121.14 g/mol40 mM2 M121.1 g242.2 g
    Acetic Acid (glacial)60.5 g/mol20 mM1 M30.25 ml60.5 ml
    EDTA Sodium salt dihydrate372.24 g/mol1 mM50 mM9.3 g18.6 g

    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%.

    Reagents

    • Tris Base
    • Acetic acid (glacial)
    • Disodium EDTA
    • Distilled water

    Materials and instruments

    • Glass Beaker
    • Weighing balance
    • Magnetic stirrer and pellet
    • pH meter
    • Measuring cylinders

    Procedure

    • 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.

    References

    wikipedia

    History and principles of conductive media for standard DNA electrophoresis.

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