Submitted to: American Chemistry Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/26/2007
Publication Date: 3/26/2007
Citation: Laszlo, J.A., Evans, K.O. 2007. Influence of surface hydrophobicity on immobilized lipase activity [abstract]. American Chemistry Society. Poster #220. p. 43. Available:http://dx.doi.org/10.1016/j.molcatb.2007.06.010. Interpretive Summary: The design of systems employing enzymes to transform vegetable oil to new products requires greater in-depth knowledge of the steps involved in the transformation, as some of these steps have a tremendous impact on the speed at which the transformation occurs. Enzymes used for modifying oils usually are placed on some kind of inert support material, which allows the enzyme to be used repeatedly. In the present work, we have examined the importance of support material surface properties on the activity and structure of an enzyme. Changing support chemical properties from water-liking (hydrophilic) to water-repellant (hydrophobic) dramatically improved enzyme activity. This information will help us and our industrial collaborators to cost-effectively produce vegetable oil derivatives.
Technical Abstract: Candida antarctica lipase B (CALB) has considerable commercial synthetic utility, particularly in the nonaqueous preparation of chiral pharmaceuticals, polymers, and various bio-based materials. CALB is typically used in an immobilized form, such as Novozym 435, in which the enzyme is non-covalently adsorbed to an acrylic bead. The effect of surface properties on immobilized CALB were examined. Gold surfaces were covered with self-assembled monolayers terminated with either a methyl or hydroxyl group (hydrophobic and hydrophilic surfaces, respectively). A quartz crystal microbalance and an atomic force microscope were used to determine the extent and orientation of CALB binding to each surface. Hydrolysis assays with immobilized CALB showed that the enzyme much preferred the hydrophobic surface, although protein coverage was similar for both types of surfaces. Although CALB is known not to display interfacial activation, as other lipases commonly do, surface hydrophobicity clearly impacts CALB orientation and activity to a positive extent.