Neopullulanase Exhibits Distinct Specificity toward Amylose and Amylopectin

抄録

Neopullulanase was the key enzyme to open the door for the formulation of the concept of the aamylasefamily. The enzyme catalyzes both hydrolysis and transglycosylation at α-1, 4- and α-1, 6-glucosidic linkages through one active center. We found a unique macromolecule recognition by the enzyme. A mixture of amylose and amylopectin from various sources was used as the substrate. Neopullulanase completely hydrolyzedamylose to maltose and a small amount of glucose, but scarcely hydrolyzed amylopectin. Although the molecular mass of potato amylopectin (approximately 10⁸ Da) decreased slightly, the degradation of amylopectincompletely halted at the molecular mass of approximately 10⁷Da. This difference in action on two macromolecules was also found in cyclomaltodextrinase and maltogenic amylase from Bacillus licheniformis.