Studies on the Properties and Co-immobilization of Manganese Peroxidase

White-rot fungus manganese peroxidase (MnP) oxidizes a wide range of substrates, rendering it an interesting enzyme for potential applications. The stability of MnP can be improved by immobilization. With sodium alginate, gelatin or chitosan as a carrier, and glutaraldehyde as the crosslinking agent. MnP was co-immobilized using the embed-crosslinked method and the adsorb- crosslinked method. The immobilization conditions and the partial properties of the three immobilized enzymes were investigated. When compared with the free enzyme, the optimum pH values and the temperatures of the three immobilized MnPs carried by alginate, gelatin, and chitosan were respectively shifted from 7.0 to 5.0, 5.0 and 3.0, and from 35 °C to 75 °C, 55 °C and 75 °C. The thermostabilities of the three immobilized MnPs were considerably better than those of the native enzyme. The chitosan-immobilized enzyme was stable in the wide range of pH 2.2 to 11. The enzyme activities of the three immobilized MnPs decreased by less than 5 % even after repeated use for 6-9 times. The ability of decolourizing azo dyes in static and shaky situation by gelatin-immobilized MnP approached to the free enzyme, and there was no loss of enzyme activity during 2 repeated batch reactions.