Purification and characterization of a novel glucoamylase from Fusarium solani

Thermostable enzymes are currently being investigated to improve industrial processes of starch saccharification. A novel glucoamylase was purified to electrophoretic homogeneity from the culture supernatant of Fusarium solani on a fast protein liquid chromatographic system (FPLC). The recovery of glucoamylase after gel filtration on FPLC was 31.8% with 26.2-fold increase in specific activity. The enzyme had a molecular mass of 40 kDa by SDS-PAGE and 41 kDa by gel filtration. The glucoamylase exhibited optimum activity at pH 4.5. The K cat and K m were 441/min and 1.9 mg/ml, respectively, for soluble starch, specificity constant ( K cat/ K m) was 232. The enzyme was thermally stable at 50 °C and retained 79% activity after 60 min at this temperature. The half-life of the enzyme was 26 min at 60°C. The enzyme was slightly stimulated by Cu 2+ and Mg 2+ and strongly inhibited by Hg 2+, Pb 2+, Zn 2+, Ni 2+ and Fe 3+.