Chelex 100 resin

The Chelex® 100 method was one of the first extraction techniques adopted by the forensic community. Chelex®® 100 is a resin that is composed of styrene-divinylbenzene

Chelex Extraction

Figure 4.1 The Chelex® 100 extraction is quick and easy to perform. (a) The cellular material is added to 1 ml of TE (1 mM EDTA, 10 mM Tris: pH 8.0) and incubated at room temperature for 10-15 minutes. (b) The tube is centrifuged at high speed to pellet the cellular material and the supernatant is removed. (c) the pellet of cellular material is resuspended in 5 % Chelex®, the tube is incubated at 56 °C for 15-30 minutes and then placed in a boiling water bath for 8 minutes. The tube is centrifuged at high speed for 2-3 minutes to pellet precipitated protein. (d) The supernatant contains the DNA and can be used directly in a PCR

Figure 4.1 The Chelex® 100 extraction is quick and easy to perform. (a) The cellular material is added to 1 ml of TE (1 mM EDTA, 10 mM Tris: pH 8.0) and incubated at room temperature for 10-15 minutes. (b) The tube is centrifuged at high speed to pellet the cellular material and the supernatant is removed. (c) the pellet of cellular material is resuspended in 5 % Chelex®, the tube is incubated at 56 °C for 15-30 minutes and then placed in a boiling water bath for 8 minutes. The tube is centrifuged at high speed for 2-3 minutes to pellet precipitated protein. (d) The supernatant contains the DNA and can be used directly in a PCR

copolymers containing paired iminodiacetate ions [7]. The resin has a very high affinity for polyvalent metal ions, such as magnesium (Mg2+); it chelates the polyvalent metal ions and effectively removes them from solution.

The extraction procedure is very simple, the Chelex'® 100 resin, which is supplied as beads, is made into a 5 % suspension using distilled water. The cellular material is incubated with the Chelex®® 100 suspension at 56 °C for up to 30 minutes. Proteinase K, which digests most cellular protein, is often added at this point. This incubation is followed by 8-10 minutes at 100 °C to ensure that all the cells have ruptured and that the protein is denatured. The tube is then simply centrifuged to pellet the Chelex®® 100 resin and the denatured protein at the bottom of the tube, leaving the aqueous solution containing the DNA to be used in PCR (Figure 4.1). The Chelex®® 100 suspension is alkaline, between pH 9.0 and 11.0, and as a result DNA that is isolated using this procedure is single stranded.

The major advantages of this method are: it is quick, taking around 1 hour; it is simple and does not involve the movement of liquid between tubes, thereby reducing the possibility of accidentally mixing samples; the cost is very low; and it avoids the use of harmful chemicals. Importantly, it is amenable to a wide range of forensic samples

[7] . The DNA extract produced using this method is relatively crude but sufficiently clean in most cases to generate a DNA profile.

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  • Tiblets
    What is chelex 100 resin?
    5 months ago
  • rose
    Why is the Chelex method especially beneficial for forensic applications?
    10 days ago

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