Chelex-100
Definition
Styrene-divinylbenzene ion-exchange resin with iminodiacetate chelating groups. Used at 5% w/v in forensic DNA extraction to bind divalent metal cations during boiling lysis. Product is single-stranded DNA in aqueous supernatant.
- Composition
- Styrene-divinylbenzene resin, iminodiacetate groups
- Working concentration
- 5% w/v
- Mechanism
- Binds divalent metal cations during boiling lysis
- Yield
- Single-stranded DNA in aqueous supernatant
Common questions
Why does Chelex extraction only give single-stranded DNA?+
The boiling step needed to lyse cells and inactivate nucleases also denatures the double helix, and unlike organic or column extraction there is no subsequent step that reanneals or purifies double-stranded product, so the recovered DNA stays single-stranded.
What is Chelex-100 protecting the DNA from during boiling?+
It chelates the divalent metal ions, mainly magnesium, that nucleases require as cofactors, so binding them up starves any residual DNase activity even as the sample is heated to lyse the cells.
Related terms
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