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KMID : 0578319970070060730
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Molecules and Cells
1997 Volume.7 No. 6 p.730 ~ p.737
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Purification and characterization of a Manganese-containing Superoxide dismutase from a Carboxydobacterium, Pseudomonas carboxydohydrogena
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An Su-Sun
Kim Young-Min
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Abstract
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Superoxide dismutase from pseudomonas carboxydohydrogena, a carboxydobacterium, grown on carbon monoxide was purified 37.6-fold in seven steps to homogeneity, with a yield of 1.4%. The final specific activity was 2,396 units per mg protein as determined by an assay based on a 50% decrease in the rate of cytochrome c reduction. The molecular weigh of the native enzyme was determined to be 42,500. Sodium dodecyl sulfate gel electrophoresis revealed two identical subunits of molecular weight 21,700. The optimal pH for enzyme activity was found to be 9.0. The enzyme was stable to heat treatment. The isoelectric point of the native enzyme was found to be 7.1. The enzyme showed an absorption peak at 280 nm with a shoulder at around 289 nm. Sodium azide, but not sodium cyanide and hydrogen proxide, was found to inhibit the enzyme activity. One mol of native enzyme was found to contain 1.09 g-atom of manganese. Analysis of amino acid composition revealed that the enzyme contains cysteine. The superoxide dismutase of P. carboxydovorans. The enzyme showed partial identity to Hydrogenophaga pseudoflava and Escherichia coli enzymes, but no identity to Acinetabacter sp. strain JCl enzyme.
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