Protein solubility is dependent on the ionic strength of the solution, among other factors. Two distinct phenomenon of protein solubilization are seen in general: 1) Salting in: At low salt concentrations, the solubility of the protein increases with increasing salt concentration (i.e. increasing ionic strength). 2) Salting out: As the salt concentration (ionic strength) increases, the solubility of the protein begins to decrease. At certain ionic strength, the protein will be almost completely precipitate from the solution. Since proteins differ markedly in their solubility at high ionic strength, salting-out is a very useful procedure to assist in the purification of a given protein. Ammonium sulfate has been widely used in salting out