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KMID : 0578319910010040407
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Molecules and Cells
1991 Volume.1 No. 4 p.407 ~ p.413
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Methanol Dehydrogenase of an Obligate Methanolotroph, Methylobacillus sp. Strain SK1
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Kim, Si Wouk
Ro, young Tae/Kim, Young Min
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Abstract
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A methanol dehydrogenase of Methylobacillus sp. strain SKI, an obligate methanolotroph growing only on methanol, was purified 8-fold in five steps to homogeneity, with a yield of 15%. The final specific activity was 981.5 units per min per mg of protein, as determined by an assay based on the methanol-dependent reduction of dichlorophenol indophenol. The molecular weight of the native enzyme was determined to be 99,000. Sodium dodecyl sulfate-gel electrophoresis revealed two nonidentical subunits of molecular weights 60,000 and 8,500. The enzyme activity required the presence of ammonium ions in the reaction mixture. The optimal temperature and pH for the enzyme activity were found to be 70 C and 10.0, respectively. The isoelectric point of the native enzyme was found to be 9.4; the K. for methanol was 660 M. The enzyme showed a broad substrate specificity for primary and secondary alcohols, aldehydes, and methylamines. The enzyme was found to have an absorption peak at 340 run. The enzyme was insensitive to several metal chelating and protein modification agents. Analysis of amino acid composition revealed that the enzyme contains no cysteine. Crystals of the purified enzyme appeared as hexagonal plates. The methanol dehydrogenase of Methylobacillus sp. strain SKI was found to have antigenic sites identical to those of Methylomonas sp. YKl enzyme.
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KEYWORD
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