Study On Extraction Of Bovine Serum Albumin By Reversed Micelles

Using BSA as a model protein, the extraction of the protein by reversed micelles system of CTAB/isooctane/1-pentane was studied in this paper. The research is focused on the following three aspects. Firstly, the optimal conditions for extraction of BSA are investigated, and then, back-extraction of BSA in reversed micelles is studied. Finally, BSA is extracted from bovine blood serum according to selectivity of CTAB/isooctane/1-pentane to BSA.Extraction experiments include the two aspects. (1) Effect of some parameters, such as pH value, the type and concentration of ions in aqueous phase, the content of surfactant, proportion of co-solvent in reversed micelles, temperature, stirring velocity of extraction and ratio of oil to water, on extraction ratio of BSA was examined, and the optimal conditions for extraction of BSA ware obtained. Experimental results show that electrostatic interaction is the major driving force in the extraction process, the extraction ratio of BSA increased remarkably in the pH region higher than 5. For different kinds of ions, usually the extraction ratio of BSA decreased with increasing the ion concentration, such a decrease is due to electrostatic hindrance by the ions. Adding 1-pentane as co-solvent in the reversed micelles is beneficial to the extraction. The optimal conditions are as followings: CTAB 0.02-0.04mol/l, pH 9.0-11.0, ion concentration KCl/NaCl 0.05-0.2mol/l, proportion of co-solvent 0.2-0.4, room temperature, stirring velocity 200-300rpm, ratio of oil to water 0.67-1.5. Under the optimum conditions, the extraction ratio of BSA can reach as high as 98%. (2) Simply back-extraction experiments were done to prove that BSA'S activity is well kept.According to extraction conditions of BSA, the back-extraction is also investigated, the following parameters were examined, pH of back extraction aqueous phase, ion concentration, ratio of oil to water, back extraction time. According to the experiments, the lower concentration of BSA in the feed is, the higher extraction ratio and back extraction ratio would be obtained. The back extraction ratio can reach more than 80% as pH approaching to BSA'S pi. The main reason is that the process is controlled by electrostatic interaction. Increasing ion concentration is disadvantageous for BSA back extraction.Extraction of a -amylase and extraction of BSA from a mixture protein solution, proving that CTAB/isooctane/1-pentane has certain selectivity to BSA, target protein can be extracted by difference of their pI. The reversed micelles system also was reused to extraction BSA from bovine blood serum.