Improved thermal stability of phytase from Yersinia intermedia by physical adsorption immobilization on amino-multiwalled carbon nanotubes

摘要

Phytase is used in poultry diets to hydrolyze and release of phytate-bound phosphorus. Immobilization on nanomaterials optimizes enzyme's thermal stability and reusability. This study aimed to immobilize the recombinant phytase from Yersinia intermedia on the surface of amino-multi-walled carbon nanotubes (amino-MWCNTs) by physical adsorption. For this, zeta potential measurement, FTIR spectroscopic analysis, scanning electron microscope (SEM), kinetic as well as thermodynamic parameters were used to characterize immobilized phytase on amino-MWCNTs. According to results, the optimum temperature of the immobilized phytase increased from 50 to 70 degrees C and also thermal and pH stability improved considerably. Moreover, immobilization led to an increase in the value of K-m and k(cat) from 0.13 to 0.33 mM and 2220 to 2776 s(-1), respectively. In addition, the changes in activation energy of thermal inactivation (Delta E-a (D)(#)), the free energy of thermal inactivation (Delta G(D)(#)) and the enthalpy of thermal inactivation (Delta H-D(#)) for immobilized phytase increased by +11.05, +24.7 and +11.4 kj/mole, respectively, while the value of the change in the entropy of thermal inactivation (Delta S-D(#)) decreased by - 0.04 kj/mole.K. Overall, our results showed that adsorption immobilization of phytase on amino-MWCNTs increases thermal, pH and storage stability as well as some of kinetic parameters.