Immobilization of Pycnoporus sanguineus laccase on magnetic chitosan microspheres

Magnetic chitosan microspheres were prepared with reversed-phase suspension methodology using glutaraldehyde as cross-linking reagent for the enzyme immobilization. The microspheres had well-shaped spherical form with smooth surface, and its mean particle size was 5.0 mu m with a narrow size distribution. Laccase was immobilized on magnetic chitosan microspheres by adsorption and cross-linking with glutaraldehyde. The immobilization conditions and characterization of the immobilized enzyme were investigated. The immobilized laccase exhibited the maximal enzyme activity at pH 3.0. The optimal temperature for immobilized enzyme was 10 C and 55 C. The kinetic parameters, K-m and V-max, for immobilized enzyme were estimated to be 171.1 mu M and 5.9 mrnol/(1 min), respectively. The thermal, operational, and storage stabilities of the enzyme were improved greatly after they were immobilized on the surface of the magnetic chitosan microspheres. (c) 2005 Published by Elsevier B.V.