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 7 days 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 K-m value for free laccase increases significantly with the IL concentration. Slight differences were found in V-m, for free enzyme. Unusual kinetic behaviour was obtained for immobilized laccase in IL: Both V-m and K-m increased with IL concentration, resulting in increased catalytic efficiency of the immobilized enzyme in presence of IL. (C) 2013 Published by Elsevier Ltd.
keywords
AQUEOUS-SOLUTIONS; BETA-GALACTOSIDASE; CATALYTIC-ACTIVITY; ENZYME-ACTIVITY; SUPPORTS; BIOCATALYSIS; PEROXIDASE; STABILITY; REMOVAL
subject category
Agriculture; Biotechnology & Applied Microbiology; Energy & Fuels
authors
Tavares, APM; Rodriguez, O; Fernandez-Fernandez, M; Dominguez, A; Moldes, D; Sanroman, MA; Macedo, EA
our authors
Ana Paula Mora Tavares
Assistant Researcheracknowledgements
This work is supported by project PEst-C/EQB/LA0020/2011, financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), Accao Integrada Luso-Espanhola E27/09 (funded by CRUP, Portugal) and projects HP2008-0022 and CTQ2009-13651 financed by Spanish Ministry of Science and Innovation and FEDER Funds. A.P.M. Tavares and O. Rodriguez acknowledge the financial support (Programme Ciencia 2008 and Programme Ciencia 2007, respectively) from FCT. M. Fernandez and D. Moldes are grateful to Xunta de Galicia for financial support under the Maria Barbeito and Parga Pondal programs.