Interfacial adsorption of lipases on very hydrophobic support (octadecyl-Sepabeads):: immobilization, hyperactivation and stabilization of the open form of lipases

Octadecyl-Sepabeads (Mitsubishi Chemical Corporation) was used to immobilize the lipases from Candida antarctica (fraction B), from Mucor miehei and from Candida rugosa via interfacial adsorption. The activity and stability properties of the derivatives obtained using this strategy by stabilization of the open structure of the lipase were compared to other more conventional immobilized derivatives (e.g. those obtained by multipoint covalent attachment) where the lipases are likely to be immobilized exhibiting its closed structure. Lipases adsorbed on hydrophobic supports exhibited a clear hyper-activation compared to the soluble enzyme or other types of derivatives. Their specific activities were greatly improved after immobilization (M. miehei lipase derivative was even 20 times more active than the soluble enzyme). Furthermore, lipases adsorbed on hydrophobic supports were very stable against heat and organic solvents inactivation. For example, C antarctica B lipase octadecyl derivatives preserved 100% of the activity after 200h of incubation at pH 7 and 50degreesC. In addition, these derivatives remained also fully active after a very long incubation (200h) in 50% dioxane at pH 7 and 25degreesC. In spite of being immobilized by simple physical adsorption these lipase derivatives were more stable than multipoint covalently immobilized derivatives and much more stable than their respective soluble enzyme. It seems that the open structure of lipases, adsorbed on hydrophobic supports, is much more active and much more stable than the corresponding closed structure even when the closed structure is undergoing a very intense multipoint covalent attachment. (C) 2002 Elsevier Science B.V. All rights reserved.