One-step affinity purification of folate-binding protein, a minor whey protein

Folate-binding proteins (FBPs) are found in membrane-bound and soluble forms. Membrane-bound FBP acts as a folate-receptor, facilitating folate uptake into cells. Cow's milk contains a soluble FBP present in milk at a level of 6-10 mg/L, where it acts to sequester folate from the maternal circulation to ensure adequate supplies for the calf. The initial aim of our research was to develop the published, laboratory-scale affinity purification of FBP into an efficient process-scale capacity, enabling the production of gram quantities of FBP.