title: Immobilization of laccase on modified silica: stabilization, thermal inactivation and kinetic behaviour in 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid.
abstract: Laccase was immobilized on modified silica carrier. The immobilization conditions, pH and enzyme concentration were optimized. Operational stability of 10 reaction cycles showed that immobilized laccase in buffer was stable, presenting an activity loss <30%. Nevertheless, a high decrease >80% was obtained in ionic liquid (IL) solution. Activity of immobilized laccase was maintained when incubated in IL. After 7days of incubation, immobilized laccase lost 30-50% of its initial activity. Immobilization also improved thermal stability of laccase in the presence of IL. Enzyme kinetics was modelled with Michaelis-Menten model. The Km value for free laccase increases significantly with the IL concentration. Slight differences were found in Vm for free enzyme. Unusual kinetic behaviour was obtained for immobilized laccase in IL: Both Vm and Km increased with IL concentration, resulting in increased catalytic efficiency of the immobilized enzyme in presence of IL.
authors: LSRE - Laboratory of Separation and Reaction Engineering, Associate Laboratory LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors: Ana P M
authors: AP
authors: Tavares
authors: Oscar
authors: O
authors: Rodríguez
authors: María
authors: M
authors: Fernández-Fernández
authors: Alberto
authors: A
authors: Domínguez
authors: Diego
authors: D
authors: Moldes
authors: María A
authors: MA
authors: Sanromán
authors: Eugénia A
authors: EA
authors: Macedo
mesh_terms: D004789:Enzyme Activation; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D007700:Kinetics; D042845:Laccase / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013379:Substrate Specificity
chemical_list: D004800:Enzymes, Immobilized; D007093:Imidazoles; D052578:Ionic Liquids; D012822:Silicon Dioxide; D042845:Laccase; C518739:1-ethyl-3-methylimidazolium