Impact of the iron saturation of bovine lactoferrin on adsorption to a strong cation exchanger membrane

Bovine lactoferrin (bLf) is a high-value iron-binding whey protein used for infant nutrition because of several health-promoting activities. The bLf concentration in whey is very low. Most methods for Lf enrichment use ion exchange chromatography since it is highly selective. However, established processes and emerging methods result in a rather low yield, partly due to inhomogeneous adsorption behaviour. To date, reasons for this have not been investigated. In this study, the impact of the state of iron binding on the adsorption of bLf to cation exchangers was investigated as affected by medium conditions. It was found that the iron-depleted apo Lf has a lower adsorption affinity than iron-saturated holo Lf in the acidic pH-range; e.g., at pH 4.8, close to the pH-value of acid whey, less than 70% of apo Lf adsorbed, whereas >85% of holo Lf bound. At physiological pH values, more than 90% of both forms bound.