Immobilization of exo-D-galacturonanase by coupling to a polyacrylamide type support

Abstract

Exo-D-galacturonanase (E.C. 3.2.1.67) from carrot was immobilized by covalent bonding to a polyacrylamide type support (with free carboxyl groups) activated by water-soluble carbodiimides. The activity of the immobilized enzyme (under optimal reaction conditions of the immobilization) was around 43% of the activity of the free enzyme. The pH-optimum of activity was shifted from 5.1 to 5.3. The immobilization of the enzyme did not change its temperature optimum and the thermal stability of the enzyme was slightly increased after its immobilization. No change in the mode of action of the immobilized enzyme on a polymeric substrate or digalacturonic acid was observed. When sodium pectate was digested with the immobilized enzyme the value of Kmapp was substantially increased and the Vapp-value dropped to 40% of that observed with the free enzyme.