Understanding protein aggregation is essential to unveil molecular mechanisms associated with neurodegenerative diseases such as Alzheimer’s, Huntington’s and spongiform encephalopathy, particularly to determine the role of interaction with cell membranes. In this study, we employ Langmuir monolayers as cell membrane models to mimic interaction with the peptide KTNMHKHMAGAAAAGAVVGGLG−OH, a fragment from the human prion protein including residues 106−127, believed to be involved in protein aggregation. Using in situ polarization-modulated infrared reflection adsorption spectroscopy (PM-IRRAS) for Langmuir monolayers and FTIR for solid films, we found that PrP106−127 adopts mainly β-sheets, random coils and β-turns in Langmuir monolayers and in Langmuir-Blodgett (LB) and cast films. This also applies to monolayers and solid films made with PrP106−127 and a brain total lipid extract (BTLE). In contrast, some α-helices are observed in the secondary structure of PrP106−127 in monolayers, and especially in solid films, of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). In summary, in a model representing brain cells (BTLE), the secondary structure of PrP106−127 is typical of fiber aggregates, while aggregation is unlikely if PrP106−127 interacts with a membrane model (DOPC) characteristic of mammalian cells.

了解蛋白质聚集对于揭示与神经退行性疾病（例如阿尔茨海默氏病，亨廷顿氏病和海绵状脑病）相关的分子机制至关重要，尤其是确定与细胞膜相互作用的作用。在这项研究中，我们采用Langmuir单层膜作为细胞膜模型，以模拟与肽KTNMHKHMAGAAAAGAVVGGLG-OH的相互作用，后者是人病毒蛋白的一个片段，包括残基106-127，据信与蛋白质聚集有关。原位使用极化调制红外反射吸附光谱（PM-IRRAS）用于Langmuir单层，FTIR用于固体膜，我们发现PrP106-127在Langmuir单层和Langmuir-Blodgett（LB）中主要采用β-折叠，无规卷曲和β-圈。和电影。这也适用于用PrP106-127和脑总脂质提取物（BTLE）制成的单层和固体膜。相反，在PrP106-127的二级结构中，尤其是在固态膜中，PrP106-127的二级结构中观察到了一些α螺旋，即1,2-油酰基-sn-甘油-3-磷酸胆碱（DOPC）。总之，在代表脑细胞（BTLE）的模型中，PrP106-127的二级结构是纤维聚集体的典型特征，而如果PrP106-127与哺乳动物细胞特征的膜模型（DOPC）相互作用，则聚集是不可能的。