抄録
The bacterium which produces a γ-cyclodextrin forming enzyme was isolated from soil. The isolated strain No. 313 was identified as Bacillus subtilis. The enzyme catalyzed the formation of γ-cyclodextrin, and neither α-nor β-cyclodextrin were detected in the enzymatic hydrolyzates.
γ-cyclodextrin forming enzyme of Bacillus subtilis No. 313 was purified about 35-fold and shown to be a single, homogeneous protein by polyacrylamide gel electrophoresis after ammonium sulfate fractionation, DEAE-Sephadex column chromatography, Chromatofocusing by Polybuffer exchanger PBE 94, Sephacryl S-200 gel filtration and CM-Toyopearl 650M. The molecular weight and isoelectric point were 64, 000 and pH 7.1. The enzyme was most active at pH 8.0 and 65°C;, and stable up to 50°C; at pH 7.0 and in the range of pH 6.0 to 8.0 at 50°C; on 30min incubation. The apparent Km values for β-and γ-cyclodextrin were 6. 67 and 0.65mM, respectively.
