ABSTRACT
The protein is a polypeptide of amino acid residues, each of which has a certain degree of polarity or hydrophobicity. Most globular proteins fold such that their hydrophobic residues are packed to the inside of the protein and their more polar residues mostly face outward. The activity of the protein could be permanently lost, which is not what the biochemist intended. Salting out is used in a number of biochemical techniques. It is the basis of many types of crystal growth experiments for any type of biomolecule. Some salts, however, will also disrupt the structure of the protein. The addition of the salt drove the protein towards its saturation point, without changing the protein’s concentration, by decreasing the amount of available solvent. When ammonium sulfate is used to purify proteins, it is added up to certain levels of its own saturation.
