Chelex DNA Extraction

Chelex is a cation exchange resin ( styrene-divinylbenzene copolymer containing paired iminodiacetate ions) used for DNA extraction. Resin is regenerated in dilute acid and operates in a solution of PH 4 or higher.  A 5 % suspension should have a PH between 10 and 11.

The resin strongly chelate metals and remove heme inhibitors and divalent cations. Chelex works by removing  Hematin. Hematin is a PCR inhibitor.Chelex also inhibits Mg ions and other ions that effect DNA denaturation. Chelex DNA extraction  produces shorter fragments of single stranded DNA.

It is a simple single tube process. A combination of alkaline suspension and boiling disrupts the cell membranes and releases DNA. The sample should be suspended in 5 % chelex and incubate it for 30 minutes at 56C. The sample is then boiled for 8 minutes. This  process lyses the cells and precipitates hemoglobin. The sample is then centrifuged, a portion of supernatant is used for PCR analysis. Ion exchange beads, denatured protein and cell components will be formed at the bottom of the tube. In this procedure, no effort is made to remove cell debris and other inhibitors. This can produce low-quality results.

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