A quality DNA sample is vital for a range of downstream applications, such as PCR and sequencing. DNA purification is the process of eliminating contaminants such as proteins and other cellular components from a sample in order to create a pure nucleic acids solution that is ready for use. There are a variety of DNA purification methods each with its own advantages and disadvantages based on the starting material or the application.
The initial step in DNA purification is to eliminate protein from the sample by using a protease (proteinase enzyme) or mechanical disintegration. Once the cellular debris is removed, DNA can be precipitated using ethanol to form a white, stringy precipitate. The precipitated DNA can then be resuspended using water or in a pure solution. The concentration of the DNA can then be determined by an spectrophotometry method, based upon the peak of absorbance for nucleic acids at 260nm.
Salting http://www.mpsciences.com/2021/04/08/different-types-of-pcr-reagents/ out is another common method used to purify DNA. A cellulose column is used in this process to capture and connect DNA. The cellulose matrix needs to be cleaned with detergents in order to remove contaminants. A wash buffer is then applied to get rid of the salts. DNA binds to matrix under low salt conditions and contaminating proteins and RNA can be removed by using higher salt solutions. The eluted DNA and RNA are then recovered using ethanol precipitation.
Anion exchange is also a popular method of cleaning DNA. This method makes use of a cation exchange resin to attract positively-charged DNA molecules, while neutralizing resins allow negatively charged DNA to be flushed out of the column. Once the DNA has been eluted from the anion exchange column, it can be concentrated through centrifugation and washed with ice-cold 70% ethanol to separate the DNA.
