Extraction Of Superoxide Dismutase From Corn And Effect On Ethanol Fermentation

Extraction of superoxide dismutase (SOD) from corn and effect on ethanol fermentation were studied in this paper, and the SOD obtained with no negative effect on ethanol fermentation was order to cut the production cost of alcohol.The optimal extracting conditions of SOD from whole kernel of corn were that 100g corn was dipped with 200mL 0.05mol/L phosphate buffer at 40℃ for 36h and filtered; 0.05mol/L phosphate buffer was added as much as twice corn stirring for 1h, and extracts of SOD were obtained by centrifugation. Then ammonium sulfate was added from 40% to 90%with stirring to SOD extracts to make a saturated solution, and SOD powder was gained after freezing-dry, whose specific activities were 168.3U/mg protein. Moreover, the ratio of ethanol yield of starch reached over 53.51% (95%v/v), and the ratio of ethanol yield of materials, was 33.82% (95%v/v) when ethanol fermentation was processed with whole corn residue extracted SOD, which proved that extraction of SOD from corn had no influence on ethanol fermentation, but had much starch lost.The total activities of SOD extracted from germ were 60% of SOD activities extracted from whole kernel with 11.86% of whole corn weight. However, the SOD concentration of extracts from germ was 9.79-fold more than one from whole kernel. Therefore, ethanol femented with endosperm and germ extracted SOD was selected. The optimal extracting conditions of SOD from germ were that 100g maize was dipped with 200mL 0.05mol/L phosphate buffer at 40℃ for 36h and filtered; 0.05mol/L phosphate buffer was added as much as twice germ to smash it after germ and endosperm separated, stirring for 1h, and extracts of SOD were obtained by centrifugation. Then ammonium sulfate was added with stirring to SOD extracts to make a 90% saturated solution, and SOD powder was gained after freezing-dry, whose specific activities were 334.6U/mg protein. Otherwise, the ratio of ethanol yield of starch and materials reached over 53.10% and 35.19%, respectively, when ethanol fermentation was processed with germ residue extracted SOD and endosperm, which proved that extraction of SOD from germ had no influence on ethanol fermentation, and the production cost of ethanol was reduced.The SOD extracted from corn germ was separated and purified by ammonium sulfate precipitation, DE-52 cellulose ion chromatography and Sephadex G-75 gel...