DNA Purification: Definition and Methods Involved

Whats is DNA Purification?

DNA purification is followed just after the DNA extraction as the DNA cell concentrate will also contain protein and RNA. The purification is done to remove these contaminants.

DNA Purification
The highly purified DNA sample increases the efficiency of the experiment and the chances of a false positive result are also reduced. Further, the purified DNA can be amplified using the PCR technique.

Methods for DNA Purification

1. Treatment with Alcohol

Alcohols like Methanol, Ethanol, and isopropanol can be used in DNA purification as well as DNA precipitation.

Once the DNA is precipitated, it is washed with 1 ml of alcohol and then the mixture is vortexed gently until the clear DNA pellet is observed.

After this, the sample undergoes high-speed centrifugation. The centrifugal force resulted in the separation of debris and other contaminants from the DNA at this location.

2. Gel filtration

This is a type of chromatography technique that uses molecular sieving properties of porous gel particles.

A matrix with fixed pure size allows smaller molecules to enter the pores by diffusion whereas the bigger molecules are excluded from the pores.

Thus, molecules are eluted in order of decreasing molecular size.

3. Ion-Exchange Chromatography

This is a type of chromatography technique that uses electrostatic interaction between the target molecule and other contaminants.

Nucleic acids (DNA) have a high negative charge whereas the impurities don't have significant change.

So with the help of salt Buffers, the sample can be eluted from ion exchange columns.

4. Absorption Chromatography

In absorption chromatography, nucleic acids are absorbed selectively on the silica or glass in the presence of certain salts like chaotropic salts, while other biological molecules (Impurities) do not. 

Finally, water or a low-salt Buffer can be used to elute the nucleic acids.

5. Automated DNA purification

This is a relatively new technology that is automated, rapid, and easy to perform. DNA purification using Automated machines is much more effective and accurate than manual methods. 

Automated DNA purification

Some examples of automated purification machines are the Kingfisher series by Thermofisher, MPure 12 by MP Biomedicals, Maxwell nucleic acid purification system by Promega, and QIAcube series from Qiagen.

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