255 Jose M. Guisan (ed.), Immobilization of Enzymes and Cells: Third Edition, Methods in Molecular Biology, vol. 1051, DOI 10.1007/978-1-62703-550-7_17, © Springer Science+Business Media New York 2013 Chapter 17 Improving Lipase Activity by Immobilization and Post-immobilization Strategies Jose M. Palomo, Marco Filice, Oscar Romero, and Jose M. Guisan Abstract One important parameter for the application of lipase catalysts in chemical industries is the specific activity displayed towards natural or unnatural substrates. Different strategies to enhance the lipase activity have been described. The immobilization of lipases on hydrophobic supports by interfacial adsorption at low ionic strength permitted the hyper-activation of these enzymes by fixing the open conformation of the lipase on the hydrophobic support. Improvements of activity from 1.2- up to 20-fold with respect to the initial one have been observed for lipases from different sources. A second strategy was based on the presence of additives, in particular surfactants or ionic liquids, with hydrophobic character to enhance the activity of lipases immobilized on macroporous supports up to eightfold and even more than 100-fold in some cases for soluble lipases. Finally, a third strategy to improve the activity in immobilized lipases was based on a site-directed chemical modification of the protein by glycosylation on the enzyme N-terminal group or on a unique reactive cysteine of the enzyme by disulfide exchange using different tailor-made disulfide activated acti- vated polymers. Key words Lipase, Activation, Immobilization, Site-directed modification, Additives, Polymers 1 Introduction The improvement of the catalytic activity of enzymes is important for their different industrial applications, in particular, processes, where the enzyme is quite selective but exhibits very low activity towards non-natural substrates [1, 2]. One of the most interesting examples is lipases. These are acyl-glycerol hydrolases with a high activity towards substrate–water interfaces but very low towards soluble oils or non-natural substrates [3]. This behavior is based on a complex catalytic mechanism. Lipases exist in certain equilib- rium between a closed conformation (inactive), where the active site is isolated from the reaction medium by a polypeptide chain called lid, and an open conformation (active), where this lid is dis- placed and the active center is fully exposed to the reaction medium