Recovery of bovine glycomacropeptide as nutraceutical and its enhancement in human immunity
Bovine glycomacropeptide (GMP) is a C-terminal glycopeptide released from [kappa]-casein by the action of chymosin during cheese making. The objectives of this research were to recover and purify GMP from whey protein isolate (WPI) for use as a nutraceutical and to investigate the immunomodulatory potential of GMP. GMP was isolated from WPI by TCA-fractionation, ethanol precipitation and ultrafiltration. Different isolation methods yielded different carbohydrate profiles of GMP. GMP was found to be a potent immuno-enhanncr at low concentrations, significantly enhancing the proliferation and phagocytic activities of human macrophage-like cells, U937. The modulatory function could be radically altered by enzymatic treatments. GMP with different carbohydrate chains was shown to possess different modulatory capabilities. Sialic acid, a major component of GMP's sugar constituent, was found to be one of the factors affecting GMP's function. These results suggest that GMP, which has the ability to enhance phagocytic activities, may become a potential functional food ingredient for enhancing human immunity.