ISOLATION OF MITOGENIC GLYCOPHOSPHOPEPTIDES FROM CHEESE WHEY-PROTEIN CONCENTRATE

We investigated the immunological function of cheese whey protein conc entrate (CWPC), which is a by-product of cheese production, using mito genic activity in murine splenocytes as an index. A fraction isolated by gel filtration and anion exchange chromatography of CWPC showed hig h mitogenic activity, comparable to the activity of lipopolysaccharide (LPS). The fraction was detected as a single band on SDS-PAGE. Tt con tained calcium, inorganic phosphorus, and carbohydrate, indicating the active component to be a glycophosphopeptide (GPP). Since Pronase dig estion of GPP did not-reduce its mitogenic activity, carbohydrate rath er than peptide may be important in the activity. When applied on an a nti-beta-caseinophosphopeptide (beta-CPP) antibody affinity column, th e GPP was separated into two components, one with affinity to beta-CPP and the other without such affinity. Both the components contained N- linked oligosaccharide chains and had the mitogenic activity. These re sults demonstrate that cheese whey contains a GPP having strong mitoge nic activity.