| Superoxide dismutases are a family of metalloenzymes essential for the survival of aerobic cells; they scavenge the superoxide radical, which appears to be a toxic species of oxygen. SOD catalyzes the dismutatcon of the superoxide radicals to hydrogen peroxide and oxygen.In this experiment, the SOD producing strain - yeast Y12 was obtained from 9 strains of different yeasts and its wet weight of cells and production of SOD were all higher than that of others. Then several factors influencing the SOD production such as carbon sources, nitrogen sources, metal irons, pH, and cultivation time were investigated. The yeast Y12 produced SOD 1263u/g fresh cells in optimal condition which was 1.58 times of original strain. A SOD high-producing mutant was bred through UV. mutagenesis and its production of SOD was 1. 5 times of original strain. Moreover, it demonstrated heredity stability through continuous propagation experiment.In this paper, a proper method of cell disruption in bead mill, in which was used to release SOD from yeast was developed in contrast with 6 different methods of cell disruption, comparing to other methods such as freeze - thaw, toluene and Chloroform - Ethanol, while the specific activity of SOD increased 1. 36, 1. 70 and 4.97 times. And this approach didn't require any complicated device. It was a simple mild and inexpensive method.The SOD from yeast Y12 by fermentation has been purified by salting out with ammonium sulfate fractionation, acetone precipitation, Sephadex G - 100 gel filtration and column chromatagraph on QAE - Sephadex A - 50, the results indicated the enzyme being Cu, Zn-SOD. Its specific activity is estimat-ed as 1073.5u/mg, the yield of activity being 54. 1%, molecular weight 32, 456 dalton and the molecular weight of enzyme subunit is 16, 227 dalton. It exhibits a maximum absoration in ultraviolet at 257nm. This enzyme is similar to the Cu, Zn-SOD from animal blood erythrocyte in characterization. |
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