Extractive purification of enzymes from animal tissue using aqueous two phase systems: pilot scale studies

Pilot scale trials have been carried out to assess the feasibility of using PEG-salt aqueous phase systems for extraction and purification of enzymes from animal tissue on an industrial scale. Comminuted bovine liver was used as a starting material, and it was easy to separate a clear upper phase containing proteins of interest from a mixture containing 20% biomass, 15% PEG and 8% phosphate using a disc separator. Similar attempts with decanters were unsuccessful. Second-phase separation was simply accomplished by the addition of salt to the separated, clear upper layer and standing or allowing passage through a disc separator. The method was tested using continuous mixing on the GBF continuous mixing aqueous phase extraction plant, with and without computer control. Good separations were achieved. The enzyme superoxide dismutase was purified using this method yielding a 4-fold purification factor with respect to soluble protein and a recovery rate of 83%, with the enzyme in a clarified solution suitable for further processing by chromatographic methods. The general applicability of this method, its economics and its potential application in industry are discussed.