Department of Chemistry, University of Miami, Coral Gables, FL 33146, USA.
Colloids Surf B Biointerfaces. 2011 Oct 15;87(2):369-77. doi: 10.1016/j.colsurfb.2011.05.047. Epub 2011 Jun 12.
Lipid rafts being rich in cholesterol and sphingolipids are considered to provide ordered lipid environment in the neuronal membranes, where it is hypothesized that the cleavage of amyloid precursor protein (APP) to Aβ (1-40) and Aβ (1-42) takes place. It is highly likely that the interaction of lipid raft components like cholesterol, sphingomylein or GM1 leads to nucleation of Aβ and results in aggregation or accumulation of amyloid plaques. One has investigated surface pressure-area isotherms of the lipid raft and Aβ (1-40) Langmuir monolayer. The compression-decompression cycles and the stability of the lipid raft Langmuir monolayer are crucial parameters for the investigation of interaction of Aβ (1-40) with the lipid raft Langmuir monolayer. It was revealed that GM1 provides instability to the lipid raft Langmuir monolayer. Adsorption of Aβ (1-40) onto the lipid raft Langmuir monolayer containing neutral (POPC) or negatively charged phospholipid (DPPG) was examined. The adsorption isotherms revealed that the concentration of cholesterol was important for adsorption of Aβ (1-40) onto the lipid raft Langmuir monolayer containing POPC whereas for the lipid raft Langmuir monolayer containing DPPG:cholesterol or GM1 did not play any role. In situ UV-vis absorption spectroscopy supported the interpretation of results for the adsorption isotherms.
富含胆固醇和神经酰胺的脂筏被认为在神经元膜中提供有序的脂质环境，据推测，淀粉样前体蛋白 (APP) 被裂解为 Aβ (1-40) 和 Aβ (1-42) 就在这里发生。脂筏成分（如胆固醇、神经酰胺或 GM1）的相互作用很可能导致 Aβ 的成核，并导致淀粉样斑块的聚集或积累。有人研究了脂筏和 Aβ (1-40) Langmuir 单层的表面压力-面积等温线。压缩-减压循环和脂筏 Langmuir 单层的稳定性是研究 Aβ (1-40) 与脂筏 Langmuir 单层相互作用的关键参数。结果表明，GM1 使脂筏 Langmuir 单层不稳定。研究了 Aβ (1-40) 在含有中性（POPC）或带负电荷的磷脂（DPPG）的脂筏 Langmuir 单层上的吸附。吸附等温线表明，胆固醇的浓度对于 Aβ (1-40) 在含有 POPC 的脂筏 Langmuir 单层上的吸附很重要，而对于含有 DPPG:胆固醇或 GM1 的脂筏 Langmuir 单层，胆固醇没有起到任何作用。原位紫外可见吸收光谱支持对吸附等温线的解释。
