Improving lipase activity by immobilization and post-immobilization strategies

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 activated polymers.