Purification and characterization of lactoferrin, lactoperoxidase, lysozyme and immunoglobulins from camel's milk

Electrophoretic SDS-PAGE analysis of purified camel and bovine milk and blood serum proteins revealed different migration patterns and molecular weights. Camel blood serum was fractionated by precipitation with saturated ammonium sulphate (SAS); the optimal recovery of immunoglobulins was at a concentration of 40% x 2 SAS. Isolation of bovine immunoglobulins, using an anion exchange resin such as DEAE-Sephacel was easier than for camel milk and serum since the difference in charge between the two subclasses of bovine immunoproteins IgG(1) and IgG(2) was greater. Protein-A chromatography was necessary as a first step followed by DEAE-Sephacel, for the purification of camel milk IgG(1) and IgG(2). Camel blood serum or milk IgG had high affinity to protein-A. However, secretory sIgA and IgM did not bind. Isolation of camel milk lysozyme, lactoferrin and lactoperoxidase was carried out using a carboxy methyl-cellex cation exchange resin. Both camel milk lysozyme and lactoperoxidase were eluted at lower salt molarity than bovine proteins. Camel milk lactoferrin was eluted at higher molarity than bovine milk lactoferrin. Molecular weights of purified camel milk lysozyme, lactoferrin and lactoperoxidase were estimated at 14.4, 79.5 and 78 kDa, respectively; for bovine milk, corresponding values were 14.4, 76 and 72.5 kDa respectively. The concentration of lysozyme in camel milk (15 mu g 100 mL(-1)) was higher than that in bovine milk (7 mu g 100 mL(-1)). Immunological cross reactions between camel and bovine minor milk proteins were very limited.