Covalent Coupling Method for Lipase Immobilization on Controlled Pore Silica in the Presence of Nonenzymatic Proteins

Candida rugosa lipase was covalently immobilized on silanized controlled pore silica previously activated with glutaraldehyde in the presence of nonenzymatic proteins. This strategy is suggested to protect the enzyme from aggregation effects or denaturation that occurs as a result of the presence of silane precursors used in the formation of the silica matrix. The immobilization yield was evaluated as a function of the lipase loading and the additive type (albumin and lecithin) using statistical concepts. In agreement with the mathematical model, the maximum coupling yield (32.2%) can be achieved working at high lipase loading (450 units·g^-1 support) using albumin as an additive. In these conditions, the resulting immobilized lipase exhibits high hydrolytic (153.2 U·mg^-1) and esterification (337.6 mmol·g^-1·min) activities. The enhanced activity of the final lipase derivative is the sum of the benefits of the immobilization (that prevents enzyme aggregation) and the lipase coating by additives that increases the accessibility of active sites to the substrate.