| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 95 === In the study of the Alzheimer’s Disease, the interaction mechanism between β-amyloid and cells are still not clear. In this study, we propose a“Recruiting Hypothesis”to investigate the interaction mechanism between Aβ & lipid monolayer. The hypothesis is that the adsorption of monomeric Aβ on the negative lipid and the conformation arrangement to form α-helical, the α-helical Aβ attach other negative lipid to form negative lipid cluster, as the negative lipid cluster induce the lateral rise in pressure of the membrane, cholesterol is recruited by the cell to form the raft-like structure to stabilize the pressure.
The objective of this research is to understand the interaction mechanism of β-amyloid (Aβ) with cell and this study is basically divided into two parts. First at all, the adsorption kinetics behaviors of Aβ on lipid monolayers were also studied by NIMA trough and we used the fluorescent-labeled cholesterol to investigate the behavior of cholesterol in membrane by fluorescent microscopy (FM). Secondary, we focused on the time -dependent structural changes of Aβ (1-40) which incubated in various liposome by circular dichroism (CD) spectroscopy.
Results from lipid monolayer trough studies showed that the rate of Aβ adsorbed onto lipid monolayer is mainly due to the electrostatic effect, and the structural rearrangements of the adsorbed Aβ is sensitive to the lipid monolayer composition. Results from the FM, the interaction of Aβ with lipid monolayer containing negative charge lipid and cholesterol brings out the recruiting behavior of the cholesterol. The variations of secondary structure of Aβ（1-40）incubated in various liposome by CD. The liposome with negative charge lipid may promote the α-helix formation; however, the β-sheet conformation was induced by the liposome with negative charge and cholesterol. The results are consistent with our “Recruiting Hypothesis”.
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