Enzyme kinetic studies using lipase immobilised in microemulsion-based organogels

Abstract

The enzyme Chromobacterium viscosum lipase has been immobilised in a microemulsion-based organogel. Kinetic studies have been performed using HPLC on the synthesis of octyldecanoate from n-octanol and decanoic acid. Catalytic efficiency of the lipase-containing gel is significantly improved by increasing the surface area per unit volume of gel in contact with the substrate-containing, external oil phase. Large amounts of enzyme can be entrapped within the gel — in our case, an enzyme concentration of 600 µg per ml of organogel was easily achieved. The catalytic activity is essentially unaffected over a wide range of gelatin concentration and w ₀-values of the gel, though in terms of purely practical considerations, compositions giving rise to “hard” gels are the most appropriate for manipulation. The low apparent activation energy of ∼20kJ mol⁻¹ for the reaction is believed to indicate a low energy barrier for diffusion of material between phases and through the enzyme-containing gel.