Purification By MCAC And Molecular Immobilization Of SOD From Maize

The crud enzyme was obtained from maize by precipitation with ammonium sulfate and sephadexG-100, then SOD was purified by metal chelating chromatography.(MCAC). The specific activity was 8591U/mg with a purification factor of 307. The purified enzyme is found to be homogeneous with a recovery rate of 29.4%. The investigation of physiochemical properties of the SOD showed that the molecular weight of the subunit was 16.0 kD.The ultraviolet absorption peak of the enzyme was found to be at 260 nm.The results of the experiments showed that the enzyme had good stability at the pH range 5-11 and displayed good thermal stability below 80 °C .The enzyme was sensitive to KCN and H2O2-The Km and Vmax were 0.1634mmol/L and 49.50mmol/min.In order to avoid the defects of SOD as medicine, The modification and immobilization of SOD with different molecular were investigated extensively. SOD was modified with PEG. It was shown in the result that the modification rate was 46% and the recovery of SOD was 81%.The stability of PEG-SOD against heat pH and trypsin degradation were increased significantly. It can be conclude that using PEG to modify SOD of maize is feasible and PEG is a kind of good chemical modification reagent.To enchance the penetration of SOD into cell, SOD satured phospholipid liposome were prepared by rotation-ultrasoniction.The entrament efficiency was tested by SOD activity .The optimum preparation condition was screened by orthogonal design. The optimum condition was as follow:the rate of satured phospholipid and cholesterol is 6:7 the temperature is 45℃ .. ultrasonication time is 4.5 min the pH is 6.8. In this condition the entrament efficiency was 48.14%.In the contrast with the natural SOD, the physiochemical character of...