Immobilization of Camel Liver Catalase on Nanosilver-Coated Cotton Fabric

Nanoparticles have the advantage of a superior surface area to volume ratio, and thus such materials are useful for enzyme immobilization. A silver nanoparticle coated cotton fabric (AgNp-CF) is used to immobilize camel liver catalase in the present work. The effect of loading levels of AgNp inside cotton fabrics on the immobilization of catalase was investigated. The results revealed that a 6 mL loading level of AgNp precursor (silver nitrate, 2 mM) at pH 8 showed the maximum immobilization efficiency (76%). The morphological properties of the cotton fabric (CF), AgNp-CF and AgNp-CF-catalase were characterized by SEM. The reusability of the immobilized enzyme was tested over ten reuses to show a 67% retained function of its initial activity. Compared with the soluble enzyme’s working pH (6.5), a rather broader working pH (6.5–7.0) was observed for the immobilized catalase. Additionally, the optimum working temperature increased from 30 for the soluble enzyme to 40 °C for the immobilized one, indicating thermal stability. The free and immobilized catalase enzyme’s Km values were 22.5 and 25 mM H2O2, respectively, reflecting the enzyme’s effective properties. The inhibitory effect of metal ions on the enzyme activity was higher toward soluble catalase than the immobilized catalase. This work has developed a method for immobilizing catalase to be useful for several applications.

Immobilization of Catalase on Chitosan/ZnO and Chitosan/ZnO/Fe2O3 Nanocomposites: A Comparative Study

The strong catalytic performance, eco-friendly reaction systems, and selectivity of enzyme-based biocatalysts are extremely interesting. Immobilization has been shown to be a good way to improve enzyme stability and recyclability. Chitosan-incorporated metal oxides, among other support matrices, are an intriguing class of support matrices for the immobilization of various enzymes. Herein, the cross-linked chitosan/zinc oxide nanocomposite (CS/ZnO) was synthesized and further improved by adding iron oxide (Fe2O3) nanoparticles. The final cross-linked CS/ZnO/Fe2O3 nanocomposite was used as an immobilized support for catalase and is characterized by SEM, EDS, and FTIR. The nanocomposite CS/ZnO/Fe2O3 enhanced the biocompatibility and immobilized system properties. CS/ZnO/Fe2O3 achieved a higher immobilization yield (84.32%) than CS/ZnO (37%). After 10 repeated cycles, the remaining immobilized catalase activity of CS/ZnO and CS/ZnO/Fe2O3 was 14% and 45%, respectively. After 60 days of storage at 4 °C, the remaining activity of immobilized enzyme onto CS/ZnO and CS/ZnO/Fe2O3 was found to be 32% and 47% of its initial activity. The optimum temperature was noticed to be broad at 25–30 °C for the immobilized enzyme and 25 °C for the free enzyme. Compared with the free enzyme optimum pH (7.0), the optimum pH for the immobilized enzyme was 7.5. The Km and Vmax values for the free and immobilized enzyme on CS/ZnO, and the immobilized enzyme on CS/ZnO/Fe2O3, were found to be 91.28, 225.17, and 221.59 mM, and 10.45, 15.87, and 19.92 µmole ml−1, respectively. Catalase immobilization on CS/ZnO and CS/ZnO/Fe2O3 offers better stability than free catalase due to the enzyme’s half-life. The half-life of immobilized catalase on CS/ZnO/Fe2O3 was between 31.5 and 693.2 min.

INCLUSION OF MAGNETIC NANOPARTICLES ОF MAGNETITE INTO PROTEIN PARTICLES OF CATALASE

In this work, vaterite microparticles with an immobilized catalase (enzyme) and magnetic nanoparticles (MNPs) of magnetite, obtained by the co-precipitation method, were used to study the enzyme activity under low frequency alternating magnetic field.

Encapsulated catalase from Serratia genus for H2O2 decomposition in food applications

The recombinant catalase isolated from a psychrotolerant microorganism belonging to Serratia genus exhibits a high activity in a wide range of pH. Due to a great catalytic potential in operational conditions, it can be used in various industrial applications whereby it acts as a hydrogen peroxide scavenger. To reduce the cost of biocatalyst the enzyme encapsulation into a hydrogel structure was proposed. The obtained results showed a high activity of encapsulated catalase in acidic conditions (pH in range 4.4 - 6.6) and at low temperatures (6-15°C). Moreover, immobilized catalase exhibited a high stability in natural media, especially in milk. Its activity during peroxide decomposition in milk, the possibility of re-using, as well as the fixed bed reactor performance confirmed wide application possibilities. High values of enzyme and substrate concentrations led to the beads burst due to rapid oxygen diffusion from the capsules, thus they are limited.

Covalently immobilized catalase on functionalized graphene: effect on the activity, immobilization efficiency, and tetramer stability

The different anchorage modes of catalase covalently linked to graphene affect the secondary and quaternary structures determining the biological properties.