Fig.8

3.8 Kinetic study of enzyme

Kinetic parameters of the free enzyme and immobilized enzyme were determined with phenylpyruvate concentrations ranging from 1.25 to 15.00 mM. Kinetic parameters were calculated based on the Michaelis‐Menten equation. The Michaelis constants were calculated and showed (Table 1). Comparing with free enzyme, the Km value of immobilized enzyme decreased, which indicated that the improvement of the affinity between enzyme (DAADH) and the substrate (Phenylpyruvate). Vmax/Km of DAADH/ZIF-8/RGO and DAADH/ZIF-8 were 1.3 and 1.6-fold of the free enzymes, respectively. The enhancement of kinetic parameters probably because ZIF-8’s and ZIF-8/RGO’s pore and inner-surface with functionality variations optimize the interior environment, which was beneficial to facilitate the substrate’s diffusion [28].