To immobilize lipase for enzymatic reactions in organic solvent, various functional [epoxy (GMA-fiber), hydroxyl (OH-fiber) or diethyl amino (DEA-fiber)] groups were introduced onto porous hollow-fiber membranes by radiation-induced graft polymerization of glycidyl methacrylate and chemical modification. Lipase from Candida rugosa was immobilized on polymer brushes by permeation of lipase. The activities of immobilized lipase were measured by esterification reactions between lauric acid and benzyl alcohol in isooctane. The activity of immobilized lipase on GMA-fibers, DEA-fibers and OH-fibers was 0.70 mol/(h kg-lipase), 0.50 mol/(h kg-lipase), and 2.45 mol/(h kg-lipase), respectively. Immobilized lipase on DEA-fibers or OH-fibers was reused three times after it was used in the batch reactor for 24 h. It was found that lipase activity showed no signs of denaturation. However, when native lipase was used, lipase activity remarkably decreased after reusing.
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