Purification And Characterization Of Cellulase Produced By Aspergillus Niger

An endo-β-glucanase was isolated and purified from a commercial preparation of Aspergillus niger by means of ammonium sulfate, Sephadex G100 and DEAE FF. The molecular mass was 26.4kD as estimated by SDS-PAGE.It was presumed that the optimal reaction temperature of the endoglucanase was 55 ℃ through investigating the character of endo-β-glucanase, and the optimal pH was 4.8. The values of Km and Vmax calculated from Lineweaver-Burk plots were 6.838× 10^-3g/ml and 2.906×l0^-2mg/ (ml·min) respectively. After glucose was added into the solution of endoglucanase, the change of thermostability and thermodynamic functions were studied. The protective kinetic mechanism of glucose was explored. Glucose protected the activity effectively during preservation of solution of endoglucanase. A kinetics model was brought forward and validated based on the presumption. The decreasing of both entropy and enthalpy of deactivation owing to the addition of glucose indicated that glucose made endoglucanase thermodynamically more stable.