title: Lipidation Effect on Surface Adsorption and Associated Fibrillation of the Model Protein Insulin.
abstract: Lipidation of proteins is used in the pharmaceutical field to increase the therapeutic efficacy of proteins. In this study, we investigate the effect of a 14-carbon fatty acid modification on the adsorption behavior of human insulin to a hydrophobic solid surface and the subsequent fibrillation development under highly acidic conditions and elevated temperature by comparing to the fibrillation of human insulin. At these stressed conditions, the lipid modification accelerates the rate of fibrillation in bulk solution. With the use of several complementary surface-sensitive techniques, including quartz crystal microbalance with dissipation monitoring (QCM-D), atomic force microscopy (AFM), and neutron reflectivity (NR), we show that there are two levels of structurally different protein organization at a hydrophobic surface for both human insulin and the lipidated analogue: a dense protein layer formed within minutes on the surface and a diffuse outer layer of fibrillar structures which took hours to form. The two layers may only be weakly connected, and proteins from both layers are able to desorb from the surface. The lipid modification increases the protein surface coverage and the thickness of both layer organizations. Upon lipidation not only the fibrillation extent but also the morphology of the fibrillar structures changes from fibril clusters on the surface to a more homogeneous network of fibrils covering the entire hydrophobic surface.
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, 2100 Copenhagen O, Denmark.
authors.forename: Sofie Fogh
authors.initials: SF
authors.lastname: Hedegaard
authors.affiliation: Department of Biomedical Science and Biofilms Research Center for Biointerfaces, Faculty of Health and Society, Malmo University , Per Albin Hanssons väg 35, 214 32 Malmö, Sweden.|Department of Chemistry, Faculty of Science, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen O, Denmark.
authors.forename: Marité
authors.initials: M
authors.lastname: Cárdenas
authors.affiliation: Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble, Cedex 9, France.
authors.forename: Robert
authors.initials: R
authors.lastname: Barker
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, 2100 Copenhagen O, Denmark.
authors.forename: Lene
authors.initials: L
authors.lastname: Jorgensen
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, 2100 Copenhagen O, Denmark.
authors.forename: Marco
authors.initials: M
authors.lastname: van de Weert
mesh_terms: D000327:Adsorption; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007328:Insulin / Q000737:chemistry*; D054878:Lipoylation; D018625:Microscopy, Atomic Force; D066329:Protein Aggregates; D058525:Quartz Crystal Microbalance Techniques
chemical_list: D007328:Insulin; D066329:Protein Aggregates