Abstract
In the current work, electrostatic interactions were used to immobilize the horseradish peroxidase (HRP) onto five types of ceramic materials (C) with different concentrations of oxidized metals (C1-C5). The highest immobilization efficiency (70 and 77%) was detected at 6 mg C3 and 18 enzyme units. Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) and Fourier Transform Infrared (FTIR) analysis of C3-HRP confirmed the immobilization of the enzyme. After ten reuses, the reusability analysis showed that (66%) of the C3-HRP enzyme activity was retained. For C3-HRP, the optimum pH and temperature of the soluble enzyme were shifted from 7.0 and 30 °C to 6.0 and 50 °C. Up to 40 °C and 50 °C, respectively, the soluble HRP and C3-HRP remained steady. The kinetic analysis revealed that the Km and Vmax of soluble HRP and C3-HRP were, respectively, 5.5 mM, 0.66 units, and 8 mM, 0.52 units for hydrogen peroxide (H(2)O(2)) and 35.5 mM, 3.4 units and 40 mM, 1.1 units for guaiacol. Compared to soluble-HRP, the C3-HRP exhibited a greater oxidizing affinity toward several phenolic compounds (Guaiacol, o-dianisidine, o-phenylenediamine, pyrogallol, p-aminoantipyrine). In comparison with soluble-HRP, the C3-HRP showed increased stress tolerance with Triton X-100, urea, metals, isopropanol, and dimethyl sulfoxide. The C3-HRP removed methyl orange more effectively compared to soluble-HRP.