Hydrolysis of inulin: a kinetic study of the reaction catalyzed by an inulinase from Aspergillus ficuum.

A kinetic study of the hydrolysis of inulin was performed by using as catalyst a commercial inulinase from Aspergillus ficuum. The reaction was studied carrying out initial rate as well as time course measurements. Both inulinase and invertase activities of the enzyme were taken into account, and the corresponding kinetic parameters were determined in the temperature range 30-50 degrees C. The activation energies of the turnover constant for inulinase and invertase activities were found to be similar (56-57 kJ x mol(-1)). The ratio S/I of invertase to inulinase activity was 1.6 regardless of temperature. The thermal degradation of the enzyme was also investigated up to 70 degrees C, and an activation energy of 350-370 kJ x mol(-1) was evaluated.