Abstract
(1) Isopullulanase [EC. 3. 2. 1. 57 pullulan 4-glucanohydrolase] from Aspergillus niger was highly purified by acetone-precipitation, ion-exchange chromatography and gel-filtration. This enzyme hydrolyzed α-1, 4-glucosidic linkages adjacent to α-1, 6-linkages of pullulan to produce only isopanose (6-maltosylglucose). Its substrate specificity was different from those of pullulanase [EC. 3. 2. 1. 41] and isoamylase [EC. 3. 2. 1. 68]. From the results, it was expected that isopullulanase would be used as a suitable enzyme for the structural analysis of α-1, 4-:-1, 6-glucooligosaccharide. (2) Cell free extract of Aureobasidium pullulans synthesized pullulan from UDPG in the presence of ATP. It was suggested that pullulan Would be synthesized through a sugarlipid intermediate. (3) Thermoactinomyces vulgaris α-amylase hydrolyzed α-1, 6-linkages in partial hydrolyzates of pullulan as well as α-1, 4-linkages in starch and pullulan. Pseudomonas stutzeri maltotetraose-forming amylase hydrolyzed starch from non-reducing end to produce α-anomer of maltotetraose, whereas glucoamylase and β-amylase hydrolyze starch from non-reducing end to produce β-anomer. (4) Large scale preparation of isopanose and panose from pullulan was facilitated by the use of special enzymes, isopullulanase and T. vulgaris α-amylase.
