Lipidation Effect on Surface Adsorption and Associated Fibrillation of the Model Protein Insulin

Abstract

Citation for published version (APA):Fogh Hedegaard, S., Cardenas, M., Barker, R., Jorgensen, L., & van der Weert, M. (2016). Lipidation effect on surface adsorption and associated fibrillation of the model protein insulin. Langmuir, 32(28), 7241-7249. DOI: 10.1021/acs.langmuir.6b00522 General rightsCopyright and moral rights for the publications made accessible in Discovery Research Portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from Discovery Research Portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain.• You may freely distribute the URL identifying the publication in the public portal. Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. ABSTRACTLipidation 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. 2Upon lipidation not only the fibrillation extent but also the morphology of the fibrillar structures changes from fibril clusters on the surface to a more homogenous network of fibrils covering the entire hydrophobic surface.

Control of Peptide Aggregation and Fibrillation by Physical PEGylation

“…A recent study has also highlighted that lipidation can accelerate the formation of peptide fibrils in bulk solution, at least for insulin under acidic conditions and elevated temperatures . This is interesting since our previous work with a palmitoylated vasoactive intestinal peptide mutant (“VIP-palm”) observed that the gelation of concentrated samples was induced by acidic conditions in the absence of methoxy-PEG 5kDa -cholane (“PEG-cholane”) .…”

“…25 A recent study has also highlighted that lipidation can accelerate the formation of peptide fibrils in bulk solution, at least for insulin under acidic conditions and elevated temperatures. 26 This is interesting since our previous work with a palmitoylated vasoactive intestinal peptide mutant ("VIP-palm") observed that the gelation of concentrated samples was induced by acidic conditions in the absence of methoxy-PEG 5kDa -cholane ("PEG-cholane"). 27 Since gelation of concentrated peptide solutions is generally indicative of the presence of peptide fibrils, the mechanism by which physical PEGylation apparently attenuates the aggregation/fibrillation process is worthy of further study.…”