Characterization of macrophage stimulating compound in glycated whey protein concentrate.

Whey, a by-product of cheese making, is a collection of several milk proteins and has functional and nutritional values. Whey protein concentrate (WPC) exhibits various functional effects by glycation. Studies to find sugar-binding sites in a protein having a functional effect are reported. However, it is rarely clear whether it confirms that glycated single protein exhibits the same effect of protein cluster. This study confirmed which protein sites are responsible for the effect of glycated WPC (G-WPC). β-Lactoglobulin (LG) was the major protein of G-WPC and glycated with lactose. The glycated LG increased the nitric oxide and cytokine secretion similar to G-WPC and peptide sequences of active compound was confirmed using the high molecular weight band of G-WPC. The K151 and K157 residues of LG were modified by glycation with sugar in common with G-WPC. These residues of glycated LG potentially contribute to the immune-modulation effect of G-WPC.