Purification and Properties of d-Xylose Isomerase from Alkalophilic Bacillus No. KX-6 |
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Authors: | Ho-Joeng Kwon Makio Kitada Koki Horikoshi |
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Affiliation: | The Riken Institute, Wako-shi, Saitama 351–01, Japan |
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Abstract: | An alkalophilic Bacillus No. KX-6 isolated from soil produced a d-xylose isomerase in alkaline media. The striking characteristic of this bacterium was its especially good growth in alkaline media. The d-xylose isomerase of this bacterium was purified by ammonium sulfate fractionation, DEAE-Sepharose ion exchange column chromatography and G-200 gel Alteration. The molecular weight and sedimentation constant were approximately 120,000 and 9.35 S, respectively. The enzyme was most active at pH 7~10 and was stable at pH 6.0 to 11.0. Enzyme activity was stimulated by cobalt ion but inhibited by Hg2 +, Ag2 +, and Cu2 +. Substrate specificity studies showed that this enzyme was active on d-xylose, d-glucose, d-ribose, and d-arabinose. The smaller Km value and larger Vmax value for d-xylose indicated that this enzyme is essentially d-xylose isomerase. |
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