Purification and characterization of a novel glucoamylase from Acremonium sp YT-78

A novel glucoamylase (EC 3.2.1.3, 1,4-alpha-D-glucan glucohydrolase) was purified to homogeneity from the culture filtrate of Acremonium sp. YT-78 isolated from soil. The enzyme had a molecular mass of 74 kDa by SDS-PAGE and 148 +/- 2 kDa by gel filtration, and its isoelectric point was 5.10. The optimum temperature and pH were around 50 degrees C and 5.0, respectively. The enzyme was stable in a pH range from 5.0 to 9.0 and at below 40 degrees C. The enzyme hydrolyzed alpha-D-glucans in an exo-manner and the glucose residue released by the action of the enzyme was beta-configuration. The enzyme had stronger pullulan-hydrolyzing activity than any glucoamylase so far reported. Panose, a saccharide containing an alpha-1,6-glucosidic linkage, was hydrolyzed by the enzyme, but it showed no activity towards isomaltose or dextran.