Covalent immobilization of xylanase purified from Aspergillus niger DFR-5 on the surface of glutaraldehyde activated alginate beads decreases the ‘catalytic efficiency’ but provides ‘low temperature stabilization’ effect

The manuscript aims to compare some of the kinetic properties of covalently immobilized xylanase on the surface of glutaraldehyde activated alginate beads with free xylanase. The immobilized enzyme displayed higher Vmax, km and kcat values but lower kcat/km value in comparison to its free counterpart. Overall, the ‘catalytic efficiency’ of xylanase was found to decline with immobilization. The isokinetic temperature (Tisokin) of free and immobilized xylanase was recorded at 86.5ºC with ln kd value of about -4.0. The method of immobilization provided ‘low temperature stabilization’ effect to xylanase which makes it more thermostable at temperatures lower than the Tisokin. The ability of immobilized xylanase to work better than free enzyme could be explained by increase in Ed and enthalpy along with a decrease in negative entropy after immobilization.