Enzymatic Reaction in Organic Solvent using Immobilized Lipase on the Polymer Brush

Abstract

To immobilize lipase for the enzymatic reaction in an organic solvent, various functional grope (aniline(AN), diethyl amine(DEA)) were introduced onto porous hollow-fiber membrane by radiation-induced graft polymerization of glycidyl methacrylate and chemical modification. Lipase was immobilized on polymer brush by permeation of 0.5g/l lipase solution (0.01M phosphate buffer solution) outward through the pores of fibers and subsequent chemical cross-linking of lipase molecules adsorbed onto the grafted polymer brush with glutaraldehyde (Fig.1). When the hollow fiber grafted DEA was used as immobilizing material, (we define this fiber as DEA-fiber ) lipase was immobilized at the density of 1.06 kg-lipase/kg-fiber, which is equivalent to the degree of multilayer binding of 200. The enzyme activity was measured using 6 mM lauric acid and 12 mM benzyl alcohol dissolved in anhydrous isooctane. When substrate solution was permeated outward from the inside of DEA-fiber at a space velocity of substrate solution of 482 h^-1, the lipase activity of DEA-fiber was 8.9 mol/(h kg-lipase). The enzyme activity of native lipase was 0.38 mol/(h·kg-lipase) in a batch reactor. It is found that the lipase activity was 23 times higher than native lipase by immobilization onto hollow fiber grafted DEA.