Lin Ming-Shen, Chiu Hsiu-Mei, Fan Fu-Jung, Tsai Hui-Ting, Wang Steven S-S, Chang Yung, Chen Wen-Yih
Department of Chemical and Materials Engineering, National Central University, Jhong-Li 320, Taiwan.
Colloids Surf B Biointerfaces. 2007 Aug 1;58(2):231-6. doi: 10.1016/j.colsurfb.2007.03.014. Epub 2007 Mar 27.
The objective of this research is to understand the interaction mechanism of beta-amyloid (Abeta) with cell and were basically divided into two parts. The first part focused on the time-dependent structural changes of Abeta (1-40) by circular dichroism (CD) spectroscopy, thioflavin T (ThT) fluorescence assay, and atomic force microscopy (AFM). The second part emphasized the kinetics and enthalpy of interaction between Abeta (1-40) and liposome by surface plasmon resonance (SPR) and isothermal titration microcalorimetry (ITC). Results obtained from CD, ThT and AFM confirmed the formation of 1 microm fibril after single day incubation. The driving force of kinetic interaction between Abeta and liposomes was revealed by SPR to be electrostatics. Further studies indicated that fresh Abeta has high GM1 affinity. Besides, addition of cholesterol to the liposome could alter membrane fluidity and affect the interactions of fresh Abeta with liposomes especially in the amount of Abeta absorbed and preserving the structure of liposome after adsorbing. Hydrophobicity was found to be the driving force leading to the interaction between Abeta fibrils and liposomes. These reactions are endothermic as supported by ITC measurements. When the composition of liposomes is zwitterionic lipids, the interaction of Abeta with liposomes is predominantly hydrophobic force. In contrast, the driving force of interaction of charged lipids with Abeta is electrostatic.
本研究的目的是了解β-淀粉样蛋白（Aβ）与细胞的相互作用机制，主要分为两部分。第一部分通过圆二色性（CD）光谱、硫黄素T（ThT）荧光测定和原子力显微镜（AFM），重点研究了Aβ（1-40）随时间的结构变化。第二部分通过表面等离子体共振（SPR）和等温滴定量热法（ITC），着重研究了Aβ（1-40）与脂质体相互作用的动力学和焓变。从CD、ThT和AFM获得的结果证实，孵育一天后形成了1微米的纤维。SPR揭示了Aβ与脂质体之间动力学相互作用的驱动力是静电作用。进一步研究表明，新鲜的Aβ具有较高的GM1亲和力。此外，向脂质体中添加胆固醇可改变膜流动性，并影响新鲜Aβ与脂质体的相互作用，尤其是在Aβ吸附量以及吸附后脂质体结构的保留方面。发现疏水性是导致Aβ纤维与脂质体相互作用的驱动力。ITC测量结果支持这些反应是吸热的。当脂质体的组成是两性离子脂质时，Aβ与脂质体的相互作用主要是疏水力。相反，带电荷脂质与Aβ相互作用的驱动力是静电作用。
