1999 Volume 46 Issue 4 Pages 469-473
Dextrin dextranase (DDase, EC188.8.131.52) was extracellularly secreted in a culture medium of Acetobacter capsulatum ATCC 11894 containing both glucose (5.45%) and an extremely small amount of dextrin (0.05%) as the essential carbon sources. The enzyme was simply purified by only one-step centrifugation at 4°C and 20, 000×g for 20 min, and immediately dialyzed against 50 mM acetate buffer (pH 4.5) at CC for 2-3 days. The purified DDase gave a single protein band on both Native- and SDS-PAGE. The molecular mass of the enzyme was estimated to be about 152 kDa by SDS-PAGE. The optimum pH and temperature of the enzyme were 5.2 and 38°C, respectively. The enzyme retained its original activity up to 45°C, and was stable in the range of pH 4.1-5.4 at 4°C for 24 h. The enzyme was completely inactivated by 1 mM of Hg2+ Pb2+ or KMn04. The purified enzyme effectively synthesized α-1, 6-glucan from maltooligosaccharides. The average molecular mass of the product dextran was estimated to be about 1270 kDa.