Chitosan-glutaraldehyde activated calcium pectinate beads as a covalent immobilization support

Abstract

Chitosan (Chi) and glutaraldehyde (GA) were employed, for the first time, during the activation of calcium pectinate (CP) beads. The activated beads were able to covalently immobilize the model enzyme, β-D-galactosidase (β-gal). They also exhibited much higher mechanical stability than the unactivated CP beads. Different Chi samples of different molecular weights and degrees of deacetylation (DD) were tested for their efficiency as CP activators. Moreover, the Chi-GA activation process was optimized using the Box Behnken design which predicted that activating the CP beads with a 0.6% Chi solution of pH 3.41 and a 4.74% GA solution would allow for the attainment of 6.87 U/g gel of immobilized β-gal. The verification experiment, which was performed while employing the abovementioned conditions, confirmed this prediction as 6.77 ± 0.47 U/g gel of immobilized β-gal was attained. A reusability experiment was also performed, and it showed that the β-gal immobilized onto the optimally activated CP beads maintained 56.62% of its initial activity during the thirteenth reusability cycle.