Extraction of uricase from Candida utilis by applying polyethylene glycol (PEG)/ NH4)2SO4 aqueous two-phase system

The purification of uricase from Candida utilis was performed by applying aqueous two-phase system (ATPS). Based on polyethylene glycols (PEG)/(NH4)2SO4 ATPSs, purification fold and recovery rate were demonstrated to influence the system parameters, such as PEG molecular mass, PEG concentration, ammonium sulfate [(NH4)2SO4] concentration, inorganic concentration, pH and additional amount of crude enzyme. The ATPS formed by 25% (w/w) PEG2000, 9% (w/w) (NH4)2SO4, 2% (w/w) NaCl, pH 7.5 and addition of 5% (w/w) crude enzyme showed the best separation capability. These conditions led to the 93% (w/w) recovery of uricase with 10-fold purification.