What is function of EDTA in DNA extractions?

Answer 1

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.

Answer 2

Lysis, or breaking open the cells, is the first step of DNA extraction. This is accomplished by a buffer containing tris and EDTA (ethylenediaminetetraacetic acid). EDTA binds divalent cations such as calcium and magnesium. Since these ions help maintain the integrity of the cell membrane, eliminating them with EDTA destabilizes the membrane. Tris is the main buffering component; its chief role is to maintain the pH of the buffer at a stable point, usually 8.0. Additionally, tris likely interacts with the LPS (lipopolysaccharide) in the membrane, serving to destabilize the membrane further.

Answer 3

Focusing material is DNA, To extract the DNA from Human, BLOOD must be in preserved form and must not be coagulated so as to perform subsequent extraction steps.

So to prevent Blood Clotting EDTA is used.

It behaves as chelating agent for divalent ions (Ca++, Mg++).

the question is that, why these ions are needed to be captured. Simple is that Ca++ ions are initiator of Blood Clotting. and behave as cofactor of clotting enzymes, so it must be captured by EDTA.

Hence EDTA prevents blood Coagulation( Clotting) by chelating these ions.

Divalent ions are also co-factors of DNAase enzymes (that degrade DNA).

so EDTA also prevents DNAase activity by chelating ions.

(Nawaz Naji)

Answer 4

glycerol increases the stabilization of the protein by decreasing the surface tension of water