Ion-exchange Electrochromatography For Protein Purification

In this article, an anion-exchange chromatography combined with an oscillatory transverse electric field was used to study the separation characteristic of hen egg white proteins. And retention behavior of protein in the electrochromatography was studied.First, a separation of egg white proteins was carried out using Q Sepharose Fast Flow on this electrochromatographic column and ovotransferrin and ovalbumin were gained. The frontal analysis study shows that, when useing a 2mL volume electrochromatographic column and with an oscillatory current density of 30mA, 1/20Hz, the output was 2.33 times as that without an current density at the same extent of proteins breakthrough. After adsorption, the egg white proteins were eluted by stepwise of ionic strength. When 7mL feedstock was loaded, the separation resulted in one peak of ovotransferrin with a purity of 73.74% and one peak of ovalbumin with a purity of 90.14%. The concentration factors of ovotransferrin and ovalbumin were 5.72 and 1.67, and recoveries 82.96% and 90.14%, respectively. Loading to the breakthrough point, 21mL, we got the almost the same concentration factors and a slight lower yield as that 7mL loaded. When compared with that loading 3mL and 9mL respectively without current density, the concentration factor was slightly lower, and the yield was nearly the same. Enlarging the electrochromatographic column to 6mL at the axial direction, and loading the feedstock on a proportion of 7:3 with an oscillatory current density of 30mA, 1/20Hz and without current density respectively, nearly the same high concentration factor and yield were elicited.In the experiment of studying retention behavior of protein in the electrochromatography, a pH 4.0 condition was used to ensure that no BSA was adsorbed by DEAE Sepharose Fast Flow. Parameters were received by experiment and data analysis, such as column efficiency, retention volume, and axial dispersion coefficient. The result shows, mass transfer and the column efficiency increases along with the current density. It is for the electroosmosis caused by the electric double layer on interface of ionic exchanger. Effect of current cycle on the column efficiency was also studied in this article. Axial dispersion coefficient is interrelated to the column efficiency, and its trend of change indicates that a postal flow of solute can be got in this chromatography with oscillatory transverse electric field.