Abstract
An isomalto-dextranase from Arthrobacter globiformis T6 was kinetically elucidated to be capa ble of splitting α-1, 4-glucosidic linkage of panose as well as α-1, 6-glucosidic linkage of isomalt otriose. The kinetic features of the experiments with the mixed substrates of isomaltotriose and panose, the linearity of Lineweaver-Burk plots, the dependence of the apparent maximal velocities on the mole fraction (f) of isomaltotriose in the mixed substrates, f = [isomaltotriose]/([isomaltotriose]+ [panose]) were in good agreement with those expected for a single catalytic site mecha nism. The enzyme is accompanied by isopullulanase activity, by which pullulan is endolytically hy drolyzed to release isopanose mainly. The isomalto-dextranase expressed by the recombinant E. coli cells also produced isopanose from pullulan. It was for the first time confirmed genetically that the enzyme had inherently isopullulanase activity.
