Kinetic and thermodynamic parameters of β-glucosidase immobilized on various colloidal particles from a paddy soil

To better understanding of enzyme stabilization and the subsequent catalytic process in soil environment, the kinetic and thermodynamic parameters of β-glucosidase immobilized on different-sized colloidal particles from a paddy soil were studied. Higher adsorption and lower desorption of β-glucosidase were found on fine soil colloids, which were attributed to their higher surface area and the large content of iron oxides. Immobilization of β-glucosidase decreased the Vmax values and increased the Km values, which indicated that the immobilized enzyme has an apparently lower affinity for its substrate due to structural changes of β-glucosidase or less accessibility of substrate to the active site of immobilized enzymes. The values of activation energy (Ea), activation enthalpy (ΔHa) and temperature coefficient (Q10) for the immobilized enzymes were smaller than those with free enzyme, implying that the immobilized enzymes are less temperature sensitive. Furthermore, mean values of Q10 were ranged from 1.32 to 1.50. These results indicated the higher stability of β-glucosidase after immobilization on various soil colloidal particles.