VMC 221: Veterinary Immunology and Serology (1+1)

PRINCIPLE

• Different proteins can be gradually salted out from their aqueous solution using highly soluable salts which after ionization associate strongly with water molecules. As the concentration of the salts in the protein molecule is increased after a certain level salts begin to compete with protein for the water molecule needed for their solvation. This leads to gradual precipitation of proteins based upon their requirements of water molecule remaining in solution form.
• The most commonly used salt is ammonium sulphate and it is conventional to express the final concentration in terms of % of saturation. Immunoglobulins can be quantitatively precipitated from sera at 35-40% saturation with ammonium sulphate.