Reversible adsorption of endopectin-lyase to tailor-made core-shell microspheres prepared by dispersion polymerization

The reversible adsorption behaviour of endopectin-lyase on tailor-made microspheres prepared by free-radical dispersion polymerization of styrene using a polyacid, Eudragit, as the steric stabilizer, is described. Four functional microsphere samples in the 2.0-7.7 μm-diameter range, differing in size, dispersity, diameter distribution and Eudragit content, were employed. All the microsphere samples display a very similar endopectin-lyase adsorption behaviour, which is strongly affected by the pH of the medium. Irrespective of the microsphere size and surface Eudragit content, the endopectin-lyase adsorption yield decreases with increasing pH and shows its highest value, corresponding to the highest affinity, at pH 4.7. The endopectin-lyase-adsorption-determining parameter is the Eudragit surface density. Complete and fast desorption of the enzyme in the active form from the microsphere surface was also observed. In addition, the duration of the catalytic activity of the enzyme-microsphere complex was longer than that of the free enzyme. These results show that the microsphere samples are effective chromatographic supports for pectolytic enzyme separation and purification and for the preparation of stable enzyme-microsphere complexes to be employed as biocatalysts in industrial processes.