<P> As a result of the increased demand for solvent molecules, the protein--protein interactions are stronger than the solvent - solute interactions; the protein molecules associate by forming hydrophobic interactions with each other . After dissociation in a given solvent, the negatively charged atoms from a chosen salt begin to compete for interactions with positively charged molecules present in the solution . Similarly, the positively charged cations compete for interactions with the negatively charged molecules of the solvent . This process is known as salting out . </P> <P> Soaps are easily precipitated by concentrated salt solution, the metal ion in the salt reacts with the fatty acids forming back the soap and glycerol . </P> <P> As different proteins have different compositions of amino acids, different protein molecules precipitate at different concentrations of salt solution . </P> <P> Unwanted proteins can be removed from a protein solution mixture by salting out as long as the solubility of the protein in various concentrations of salt solution is known . After removing the precipitate by filtration or centrifugation, the desired protein can be precipitated by altering the salt concentration to the level at which the desired protein becomes insoluble . </P>

Principle of salting out method of dna extraction