Studying Of Partition Behavior Of Papain In [C_nmim]X?X=Br?Cl? BF₄? Ionic Liquid Aqueous Two-Phase System

Papain was applied to food and medicine widely, as a result of its good stability, strong proteolytic, security and so on. However, The results of purifying papain by traditional methods were not satisfied. Therefore, it's urgent to looking for a new purification method to extract papain. To investigate the partition behavior of papain in the Ionic liquids aqueous two-phase system (ILATPS), [Cnmim]X(X=Br?Cl?BF4) were selected to study liquid/liquid/solid boundary line, phase diagrams, liquid/liquid equilibrium and model and verify models'accuracy. By comparison, the ILATPS was selected to optimize extraction condition by analyzing single factors and CCD. Utilize SDS-PAGE to verify results ultimately. The results are shown below:(1) Study of liquid/liquid/solid boundary lines in three ionic liquids. Slope of liquid/liquid/solid boundary lines inversely proportional to alkyl chain length, phase power and temperature of the ionic liquid. The power to phase as fellow:[Cnmim]BF4>[Cnmim]Cl>[Cnmim]Br. The areas of complete two-phase system are not the same because of different ionic.(2) Study of phase diagrams. The binodal curve was measured by means of cloud point at T=298.15K and the data was associated by Merchuk. The results were perfect with R2 over 0.977 and the average relative error less than 0.6. Complete two-phase system was constituted by binodal curve and liquid/liquid/solid boundary line to guide choosing suitable composition of ILATPS.(3) Study of liquid/liquid equilibrium. The content of each phase was measured by means of neutral titration and refractive index at T=298.15K and the data was associated by Othmer-Tobias and Bancrof. The results were satisfactory with R2 between 0.994 and 0.999, average relative error of ionic less than 0.002% and phosphates less than 0.072%. Modeling could be easy by results.(4) Study of model. Model were found by correlation with K and the content of each phase by Mathematic and Matlab at T=298.15K. The models with relative deviation less than 7.0% compared to other, have been improved greatly and predicted partition behavior of papain exactly. Models are shown:(5) Study of partition behavior of papain in the [Cnmim]BF4-NaH2PO4 with single factors and CCD by comparison. This study aimed to investigate the effects of concentration of the ionic liquid, the dosage of phosphates and papain, pH value and temperature on the partitioning behavior of papain, respectively. CCD was used to predict the extraction conditions of papain at 298.15K. The optimized extraction conditions were as follow:NaH2PO40.41 g/mL, [C4mim]BF40.34g/mL, Papain 2.62mg/mL, pH 8.28, temperature 298.15K. The results verified were effective by direct enzyme and extracted enzyme, because of average relative error were 1.7% and 3.8%.