Abstract
Isopullulanase (IPU) from Aspergillus niger ATCC 9642 is a cell-bound glycoprotein that hydrolyzes pullulan into isopanose. The sugar content of the recombinant enzyme expressed in Aspergillus oryzae M-2-3 decreased from 33.8 to 2.1% by 13 h-treatment with endoglycosidase H (Endo H), and deglycosylated rec-IPU had 65% of the original activity. 3 Deg-IPU (prepared by 3 h-treatment of Endo H; 6.8% sugar) showed the same substrate specificities, optimum pH and optimum temperature as native IPU and rec-IPU, while its kinetic parameters, ko and ko/Km values for pullulan, and Km, ko and ko/Km values for panose decreased with deglycosylation, except Km for pullulan. The oligosaccharide chains of rec-IPU were typed using lectin-peroxidase reagents and classified as hybrid- and/or high-mannose types.
