[Characterization of dextranase from Penicillium purpurogenum (Ftoll)]

An extracellular dextranase (E. C. 3.2.1.11) was purified from cell-free culture filtrates of Penicillium purpurogenum (Ftoll). The enzyme was most active at pH 5,5. The dextranase was endo-type, it split quickly isomaltotetraose into two isomaltose molecules, slowly degraded isomaltotriose, and did not act on isomaltose. The rate of isomaltooligosaccharides hydrolysis was increased with the increase of the polymerization degree. Polyols obtained from isomaltooligosaccharides were split more slowly than the respective sugars. The isomaltopentaitol was split at two glucosidic linkages, 38% of hydrolyzed linkages being the second linkage from the sorbitol end of the molecule and 62% being the third one. The degree of degradation of dextrans depended on amount of 1,6 linkages. Isomaltose and tetrasaccharides of two types, 2(2)-alpha-D-glucosylmaltotriose and linear tetrasaccharide(s), are the lowest molecular weight products of exhaustive hydrolysis of branched dextrans.