Purification and some properties of an α-D-xylosidase from Bacillus sp. No. 693-1

An α-D-xylosidase from Bacillus sp. No. 693-1 was purified by precipitation with ammonium sulfate and successive chromatography on DEAE-Toyopearl 650 and hydroxyapatite. The purified enzyme, with its isoelectric point at pH 4.25, had an apparent molecular weight of 82, 000 in SDS-polyacrylamide gel electrophoresis, and 400, 000 in gel filtration chromatography on Toyopearl HW60. The optimum pH for enzyme action was 7.5 and the optimum temperature was 45°C. The enzyme was stable from pH 6.0-8.5 and up to 45°C. The activity was inhibited by monoiodoacetic acid, p-CNB, and metal ions such as Zn2+, Cu2+, and Hg2+. The α-D-xylosidase was highly specific for α-xylosidic linkages, and hydrolyzed isoprimeverose [α-D-xylopyranosyl-(1→6)-D-glucopyranose] to produce xylose and glucose, and hydrolyzed tamarind seed polysaccharide (soluble fraction) to release xylose as well.