What is the function of EDTA in DNA extraction?
EDTA is a chelating agent and has great affinity with matel ions
and Mg-ion present in DNase as a cofactor and responsible for DNase
action that degrade the DNA,here EDTA bind with Mg-ion and nullyfy
the action of DNase.
The nuclear envelope normally protects the DNA from digestion by
nucleases. Nuclear envelope is the membrane that surrounds the
nucleus and prevents the exposure of its contents such as the DNA
to the contents of cytoplasm. In the process of DNA extraction, we
need to break down the nuclear envelope in order to access the DNA.
This would expose the DNA to nucleases and if we don't deactivate
these enzymes, they will cut and damage the DNA. Nucleases need
divalent cations such as Mg2+ to function. In order to deactivate
these enzymes we use EDTA which stands for
Ethylenediaminetetraacetic acid to our sample tissue. EDTA has four
carboxyl groups ( -COOH). In the alkaline condition of the buffer,
EDTA becomes negatively charged. The EDTA ions then form covalent
bonds with the divalent cations and prevent them from reacting with
nucleases. As a result, the enzymes are deactivated and will no
longer cause a threat to the DNA.