Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Exo-D-galacturonanase (E.C. 3.2.1.67) isolated from carrot was irreversibly adsorbed on poly(ethylene terephthalate) in a 0.1 mol l^-1 acetate buffer solution of pH 5.1. Activity of the immobilized enzyme depended on the amount of the enzyme bound to the support, on the ionic strength, and, to a very little extent, also on the pH of the reaction medium during immobilization. Activity of the immobilized enzyme dropped; the greatest relative activity (51.8%) had the preparation composed of 9.12 mg of the enzyme per 1g of the support. The pH optimum for catalytical activity of the immobilized enzyme was identical with that of the dissolved enzyme (5.1). Immobilization of the enzyme did not change its thermal optimum, and its thermal stability did not improve, either. The substrate specificity did not alter by immobilization, no differences were found in the mode of action on the polymeric substrate; digalacturonic acid was degraded by the immobilized enzyme like by the dissolved one. Differences in the kinetics of polymeric substrate degradation by the bonded exo-D-galacturonanase were manifested by a lower V' app value and by an increased K'_m value. Exo-D-galacturonanase preparation obtained by adsorption on poly(ethylene terephthalate) was extraordinarily stable during storage at 4 °C, and towards action of salts and pH changes; its operation stability was high.