Premium
Adsorption of Amyloid Beta (1‐40) Peptide to Phosphatidylethanolamine Monolayers
Author(s) -
Maltseva Elena,
Brezesinski Gerald
Publication year - 2004
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200400045
Subject(s) - monolayer , chemistry , adsorption , surface pressure , peptide , penetration (warfare) , molecule , crystallography , organic chemistry , biochemistry , physics , operations research , mechanics , engineering
The aggregation of soluble, nontoxic amyloid β (Aβ) peptide to β‐sheet containing fibrils is assumed to be a major step in the development of Alzheimer's disease. Interactions of Aβ with neuronal membranes could play a key role in the pathogenesis of the disease. Herein, we study the adsorption of synthetic Aβ peptide to DPPE and DMPE monolayers (dipalmitoyl‐ and dimyristoylphosphatidylethanolamine). Both lipids exhibit a condensed monolayer state at 20 °C and form a similar lattice. However, at low packing densities (at large area per molecule), the length of the acyl chains determines the phase behavior, therefore DPPE is fully condensed whereas DMPE exhibits a liquid‐expanded state with a phase transition at approximately 5–6 mN m −1 . Adsorption of Aβ to DPPE and DMPE monolayers at low surface pressure leads to an increase of the surface pressure to approximately 17 mN m −1 . The same was observed during adsorption of the peptide to a pure air–water interface. Grazing incidence X‐ray diffraction (GIXD) experiments show no influence of Aβ on the lipid structure. The adsorption kinetics of Aβ to a DMPE monolayer followed by IRRAS (infrared reflection absorption spectroscopy) reveals the phase transition of DMPE molecules from liquid‐expanded to condensed states at the same surface pressure as for DMPE on pure water. These facts indicate no specific interactions of the peptide with either lipid. In addition, no adsorption or penetration of the peptide into the lipid monolayers was observed at surface pressures above 30 mN m −1 . IRRAS allows the measurement of the conformation and orientation of the peptide adsorbed to the air–water interface and to a lipid monolayer. In both cases, with lipids at surface pressures below 20 mN m −1 and at the air–water interface, adsorbed Aβ has a β‐sheet conformation and these β‐sheets are oriented parallel to the interface.