Pectinases are important enzyme preparations with many industrial applications. Therefore, the immobilization of this group of enzymes is very useful in food and agricultural uses. Ad-ditionally, can inform on enzymes behaviour, because catalytic properties of immobilized biocatalysts can differ to a great extent from those of the free counterparts in solution. In fact, the carrier and immobilization technique used determine different changes in properties of a particular enzyme. Thus, kinetic parameters and temperature behaviour of both soluble and immobilised polygalacturonases (PG; EC 3.2.1.15) by adsorption on calcium alginate gels have been determined [1]. Four commercial pectinases applied in wine making were used in this study: Rapidase CX and EX (Gist Brocades) and Pectinases C and E (Wormser oenolo-gie).

Soluble and immobilised polygalacturonase followed Michelis-Menten kinetics, whereas the immobilised enzyme from Rapidase CX appeared to be a sigmoid behaviour. Its kinetics could be explained by the effect of diffusion inside the porous support against a substrate with high molecular weight [2]. In this sense, the isothermal adsorption of Rapidase CX was evaluated. Additionally, the optimum pH of the immobilised enzyme shifted to the alkaline side. Adsorbed polygalacturonase activity showed an optimum temperature 10ºC lower than that of the free enzyme. The activation energies were also calculated. Finally, the thermal sta-bility was notably improved by immobilisation.

[1] Busto, M.D., Fernández, M.J., Ortega, N., Perez-Mateos, M. 8th European Congress on Biotechnology, TH 3218, p. 374, 1997.

[2] Pifferi, P.G., Preziuso, M., Lebensm.-Wiss. U.-Technol., 20, 137-142, 1987.