Kinetic behaviour of α-galactosidase produced by Absidia griseola: a comparison between free and immobilized forms of the enzyme

In this research the characteristics of free (partially purified) and immobilized (mould pellets of Absidia griseola) -galactosidase have been investigated. Inhibition studies of the enzyme showed that p-nitrophenol and sucrose do not have any inhibitory effect on the enzyme, but that galactose is a competitive inhibitor. In the immobilized form, inhibition was lower than in the free enzyme and the level of inhibition decreased as the temperature increased. The activity and stability of free and immobilized enzyme were investigated with respect to temperature, and the results showed that the optimal temperature range of the free enzyme was 45–50 °C, while the immobilized enzyme had an optimum at 55–60 °C. The optimum pH for the free enzyme was 6.0 and the value was decreased to 5.0 by immobilizing. The experimental effectiveness factors were found to be represented as a single function of the modified Thiele modulus, including parameters such as pellet size, enzyme concentration in the pellets and substrate concentration. Both experimental and theoretical data concerning effectiveness factors are nearly the same.