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

Abstract

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 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 β-glucosidase or less accessibility of substrate to the active site of immobilized enzymes. The values of activation energy ( E a), activation enthalpy (Δ H 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 β-glucosidase after immobilization on various soil colloidal particles.