Response Surface Methodology for the Evaluation of Lysozyme Partitioning in Poly (Vinyl Pyrrolidone) and Potassium Phosphate Aqueous Two-Phase System

The partitioning of lysozyme and extraction yield in an aqueous two-phase system containing Poly Vinyl Pyrrolidone (PVP) K25 and potassium phosphate were investigated as a function of weight percent of salt and PVP in the feed, temperature, and pH. To investigate partitioning behavior, the central composite design was considered using a quadratic model. According to the results of the model, the partitioning of lysozyme was mainly due to the impact of the weight percent of the salt in the feed. However, the partitioning was expanded a little following the increase in the weight percent of the polymer. Based on the results, there was an opposite relationship between the temperature and decrement in the viscosity of PVP as the increment in the former led to the decrement in the latter. Finally, the modification in the third factor was done by increasing the pH level. Before experimenting, some values were hypothesized such as 93.69% for the maximum extraction yield, 21.23% for PVP K25, 13.99% for the salt concentrations, 7.10 for the pH value and 35.57 for the temperature. The findings of the study suggest that the hypothesized values for different variables are in line with the experimental results.