Examination of The Immobilization and Kinetics of The Laccase Enzyme on Various Clay Minerals

In this study, the immobilization of the laccase enzyme, which has a wide application area in the industry, was examined. For this purpose, commercially obtained laccase enzyme was immobilized on various clays using the physical adsorption method. The effects of pH, temperature, substrate concentration, and storage time on the activity of free and immobilized laccase were examined. As a result of the studies, the optimum pH and temperature for free laccase were obtained as 5.5 and 40 °C respectively and the optimum pH and temperature for all immobilized enzymes (bentonite, diatomite, and Bardakçı) were 5.5-6.0 and 40 °C respectively. The effects of pH and temperature on the activity of the immobilized laccase showed that the properties of the immobilized enzyme were the same as those of the free enzyme. The resulting kinetic constant values turned out to be quite close to each other. In addition, it was shown that adsorption did not significantly affect the kinetic properties of the enzyme. Only 20%-30% of immobilized laccase activity disappeared in 2 months. K_M values for free enzyme and immobilized enzymes were found as 0.0700 mM, 0.0724 mM, 0.0831 mM, and 0.0935 mM and V_max values were 0.0695, 0.0216, 0.0236, and 0.0233 mM^-1, respectively. The K_M value of the immobilized enzyme is greater than that of the free enzyme and the V_max value is smaller. The increase in resistance of the immobilized enzyme to temperature change and storage time indicates that laccase immobilization on clay is beneficial for enzyme immobilization.