A high-quality DNA sample is essential for a variety of downstream applications, including PCR and sequencing. DNA purification is the process of removing any contaminants such as proteins and other cellular elements, from a sample to make an uncontaminated nucleic acid solution that is ready to use. There are a myriad of DNA purification techniques each with its own advantages and drawbacks depending on the base material or the application.
The first step in DNA purification is to remove proteins from the sample using the proteinase (protein enzyme) or mechanical disruption. After removing the cellular debris, DNA is precipitated with the presence of ethanol, which results in the formation of a white and stringy precipitate. The DNA that is precipitated is placed in a buffer that is sterile. The concentration of DNA can be determined using spectrophotometry using the peak of nucleic acid absorbance at 260nm.
Salting out is a different method of DNA purification. A column of cellulose is utilized in Artificial gene synthesis this process to collect and attach DNA. The cellulose matrix has been pretreated with detergents in order to remove contaminants, and a wash buffer is used to flush out the salts. DNA bonds to the matrix in low-salt conditions. Contaminating proteins andRNA can be removed using higher-salt solutions. The eluted DNA and RNA are then recovered with ethanol precipitation.
Anion exchange is a common method of DNA purification. This method makes use of a cation exchange resin to attract positively-charged DNA molecules, while a neutralizing resin allows negatively-charged DNA to be removed of the column. Once the DNA is eluted from the anion exchange column it can be concentrated through centrifugation and then washed with ice cold 70% ethanol to separate the DNA.