Purification and characterization of an extracellular glucoamylase from the yeast Candida tsukubaensis CBS 6389.

The starch-degrading yeast Candida tsukubaensis CBS 6389 secreted amylase at high activity when grown in a medium containing soluble starch. The extracellular alpha-amylase activity was very low. The major amylase component was purified by DEAE-Sephadex A-50 chromatography and Ultrogel AcA 44 gel filtration and characterized as a glucoamylase. The enzyme proved to be a glycoprotein with a molecular weight of 56 000. The glucoamylase had a temperature optimum at 55 degrees C and displayed highest activity in a pH range of 2.4-4.8. Acarbose strongly inhibited the purified glucoamylase. Debranching activity was present as demonstrated by the release of glucose from pullulan.