Separation of immunoglobulins and lactoferrin from cheese whey by chelating chromatography

Different adsorption and chelating chromatographic methods were used to isolate immunoglobulins and lactoferrin from cheese whey. Among three adsorption solid supports (silica, controlled pore glass, and alumina), controlled pore glass showed the highest adsorption of immunoglobulins; however, its capacity was low. 1,4-Butanediol diglycidyl etheriminodiacetic acid on Sepharose 6B was loaded with copper ion and used for the same purpose. Of the two peaks eluted using pH gradient, the first yellowish peak was rich in lactoferrin and the second was rich in Ig. The purity of IgG in the Ig rich fraction as indicated by radial immunodiffusion was 77.2 and 53.0% for acid whey and Cheddar cheese whey, respectively. The capacity of the column was high; a 25-ml copper charged column could absorb Ig from 1 L of cheese whey. Modification of histidine residues in Ig with diethyl pyrocarbonate almost completely eradicated the adsorption, implicating the coordination compound formation between histidine in Ig and Cu on the chelating column as the adsorption mechanism. Enzyme-linked immunosorbent assays of the Ig thus separated demonstrated their binding activity against lipopolysaccharides extracted from Escherichia coli, Salmonella typhimurium, and Bordetella parapertussis.