Fetuin Purification from Fetal Bovine Serum by Ion-Exchange Chromatography

Background: Fetuin (Ft) is the most abundant protein in fetal bovine serum (FBS) and is considered one of its essential components. This acidic glycoprotein plays a key role in cell adhesion and proliferation and is vital for maintaining in vitro cultures of animal and human cells, tissues, and organs. FBS is a natural source for Ft purification. However, the high demand for FBS as a standard reagent in cell culture severely limits its availability for use as a raw material for protein purification. Furthermore, the industrial production of FBS results in a significant amount of contaminated FBS. This contaminated fraction can thus be utilized for Ft recovery. Methods: In this work, we present a novel method for Ft recovery from FBS using a single chromatographic step based on anion exchange chromatography under acidic conditions. Results: Optimal adsorption conditions for Ft were studied using response surface methodology (RSM), which suggested a buffer pH of 4.2 and an FBS dilution of 40%. However, increasing the pH to 5 resulted in a 28% increase in Ft recovery, although with a slight reduction in Ft purity to 88%. A scale-up to half a liter of FBS was performed using a 400 mL column. A single-step elution with 0.3 M NaCl was employed, yielding an Ft recovery of 90% with a purity greater than 82%. Conclusions: The purified Ft demonstrated biological activity as a growth promoter in MDBK cell culture when utilized in a serum-free culture medium.