Demonstration of a strategy for product purification by high-gradient magnetic fishing: recovery of superoxide dismutase from unconditioned whey.

摘要

A systematic approach for the design of a bioproduct recovery process employing magnetic supports and high-gradient magnetic fishing (HGMF) is described. The approach is illustrated for separation of superoxide dismutase (SOD), an antioxidant protein present in low concn. (0.15-0.6 mg/l) in whey, a dairy industry by-product. Initial process design consisted of ligand screening, and found that metal chelate supports charged with Cu(II) ions were the most suitable. Systematic, sequential optimization of conditions for product adsorption, support washing and product elution was then performed. Next, the capacity of a novel high-gradient magnetic separator (designed for biotechnological applications) for trapping and holding magnetic supports was determined. Finally, all of the above elements were assembled to deliver a HGMF process for isolation of SOD from crude sweet whey. The complete process consists of: binding SOD using Cu2+-charged magnetic metal chelator particles in a batch reactor with whey; recovery of the 'SOD-loaded' supports by high-gradient magnetic separation; washing out loosely-bound and entrained proteins and solids; elution of the target protein; and recovery of the eluted supports from the HGMF rig. Efficient recovery of SOD was demonstrated at an approx. 50-fold increased scale (compared with magnetic rack studies) in 3 HGMF experiments, in the best of which an SOD yield of >85% and purification factor of approx. 21 were obtained.