[Purification and properties of inulinases from Aspergillus niger M89]

Four inulinase components were purified from Aspergillus niger M89 by (NH4)2SO4 fractionation, Sephadex G-200 gel filtration, DEAE-cellulose chromatography and polyacrylamide gel electrophoresis (PAGE). The molecular weight of EI EII EIII and EIV were indicated to be 102.6, 97.9, 62.5 and 36.5 kD respectively by SDS-PAGE. Measured by isoeleetric focusing, their isoelectric points were 4.15, 4.24, 4.48 and 4.15 respectively. Four forms of inulinase exibited maximal inulinase activity between 55-60 degrees C with optimal pH 4.0-5.0. There were some difference in their thermal stability. The little the molecule of the component was, the stronger its thermal stability was. All of four components were exo-acting inulinases.