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 filteration. The molecular weight and sedimentation constant were approximately 120, 000 and 9.35S, 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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Kwon et al. (1987) studied this question.