A novel dextran dextrinase from Gluconobacter oxydans DSM-2003: purification and properties

Dextran has already been widely applied in food, pharmaceutical, and chemical industries. In this study, a novel intracellular dextran dextrinase (DDase, EC 2.4.1.2) from Gluconobacter oxydans DSM-2003 exhibiting catalytic activity to synthesize dextran from maltodextrin was purified to homogeneity by ultrasonic cell disruption, ion exchange chromatography, and gel filtration. This procedure showed 187.5-fold purification from the cell-free extract with 41.9 % yield. And the apparent molecular weight was estimated to be 62 kDa by SDS-PAGE. It was different from the reported literatures, which found that the molecular weight of intracellular and extracellular DDase of G. oxydans ATCC-11894 was 300 and 152 kDa, respectively. Otherwise, it showed different physicochemical characteristics (optimal temperature and pH, thermal, pH stability, effect of metal ions) from the DDase of G. oxydans ATCC-11894. This indicated that DDase of G. oxydans DSM-2003 was a novel one compared to the reported literatures.