Application of response surface methodology to the modeling of α-amylase purification by aqueous two-phase systems

Mathematical models concerning the purification of α-amylase from the cultivation supernatant of Bacillus subtilis in a polyethylene glycol-citrate aqueous two-phase system (ATP) are established with response surface methodology. The PEG3350, citrate and sodium chloride concentrations were selected as variables to evaluate the purification impact factors in aqueous two-phase system, including partition coefficients of α-amylase, total protein, purification factor and α-amylase yield. An experimental space with two-fold purification and over 90% yield of α-amylase is achieved through the optimized condition basing on the model. Two systems with low viscosity within said space were further selected to perform α-amylase purification and the experimental results coincide well with the calculation of the models, which indicates that the model provides a promising tool for experimental design of protein purification by aqueous two-phase system.