Question:
What is the role of proteases in DNA extraction?
The Protein Man Says:
What specific role do proteases play in DNA extraction and just how important are they in completing the process? If you are performing DNA extraction as a preliminary step in detecting bacteria and viruses in the environment or as a way of diagnosing disease/genetic disorders, you probably know that the removal of proteins in the sample via the appropriate protease is an important step.
To successfully extract pure DNA from a sample, you need to destroy the cell walls first to expose the DNA material. This can be done by employing different physical (blending, grinding, high temperature treatments, microwave treatments and/or sonication or the application of sound energy to agitate the particles in the sample solution) and chemical methods that are caustic to the cell membrane but are virtually harmless to the DNA.
Once cell lysis is completed, you can then proceed with the removal of the membrane lipids by adding an appropriate detergent or surfactant followed by the removal of proteins with the aid of proteases. While the latter is considered to be an optional step in the process, most researchers prefer to go through it for a number of very good reasons.
For one, proteases catalyze the breakdown of contaminating proteins present in the solution to its component amino acids. It also degrades any nucleases and/or enzymes that may be present in the sample. This is of vital importance since these chemical compounds can attack and destroy the nucleic acids in your sample. For sure, compromising the integrity of your sample is the last thing on your mind, right? You can prevent this from happening by using the appropriate protease to clean up your sample.
After all the unwanted proteins and enzymes have been removed from your sample, you can then proceed with the precipitation and purification of your precious DNA sample – one that is fit for stringent DNA testing.
Image By: Alfred Hermida
