Kinetic and thermodynamic parameters of beta-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 beta-glucosidase immobilized on different-sized colloidal particles from a paddy soil were studied. Higher adsorption and lower desorption of beta-glucosidase were found on fine soil colloids, which were attributed to their higher surface area and the large content of iron oxides. Immobilization of beta-glucosidase decreased the V(max) values and increased the K(m) values, which indicated that the immobilized enzyme has an apparently lower affinity for its substrate due to structural changes of beta-glucosidase or less accessibility of substrate to the active site of immobilized enzymes. The values of activation energy (E(a)), activation enthalpy (DeltaH(a)) and temperature coefficient (Q(10)) for the immobilized enzymes were smaller than those with free enzyme, implying that the immobilized enzymes are less temperature sensitive. Furthermore, mean values of Q(10) were ranged from 1.32 to 1.50. These results indicated the higher stability of beta-glucosidase after immobilization on various soil colloidal particles.