An isomalto-dextranase accompanied by isopullulanase activity from Arthrobacter globiformis T6.

Abstract

An isomalto-dextranase was highly purified from the cell-free culture broth of Arthrobacter globiformis T6 by consecutive column chromatographies on CM-cellulose. The final purified enzyme was judged to be homogeneous on polyacrylamide gel, SDS-polyacrylamide gel and ampholine electrophoresis.The isopullulanase to G2-dextranase activity ratio was almost the same (ca. 0.18%) at each purification step. The isopullulanase activity appeared at exactly the same position as the G2-dextranase activity on CM-cellulose column chromatography, analytical polyacrylamide gel electrophoresis and isoelectric focusing. The stabilities of the isopullulanase as to pH and temperature well coincided with those of the G2-dextranase. Furthermore, the inactivation profiles of the isopullulanase with various metal ions and inhibitors were almost the same as those of the G2-dextranase. From these results, it was strongly suggested that a single enzyme molecule was responsible for both the G2-dextranase and isopullulanase activities.