二茂铁修饰Aβ疏水段五肽的电化学性质及自组装研究

Electrochemical Properties and Self-assembly of Ferrocene Modified Hydrophobic Pentapeptide Fragment of β-Amyloid

五肽Lys—Leu—Val-Phe-Phe（即PKLVFF）是β-淀粉样肽（Aβ）疏水核心片段，其自组装方式对Aβ的聚集具有重要影响。在本文中，首先对二茂铁修饰的五肽，即Fc－Lys（Z）－Leu－Val－Phe—Phe—OMe（简称Fc-KLVFF）的电化学性质进行了研究，结果表明，在0．4～0．8V范围内出现了一对可逆的氧化还原峰，氧化峰和还原峰电位分别为0．626和0．544V，峰电位之差△Ep为82mV，峰电流密度之比，Ipm／Ipc为1．08，扩散系数D0=1．784×10^-6cm^2·s^-1。其次通过TEM观察到Fc-KLVFF在甲醇溶液中自组装成纳米管，傅里叶红外光谱分析表明纳米管的二级结构主要为β-折叠．紫外-可见和荧光光谱证实苯丙氨酸残基芳香环之间的π-π堆积作用在其自组装成纳米管时起着重要作用。最后提出了Fc-KLVFF的自组装机理模型。

The self-assembly of ferrocene modified hydrophobic pentapeptide fragment of β-amyloid, Fc-KLVFF, is studied. Fc-KLVFF can self-assemble into nanotubes in methanol, as confirmed by transmission electron microscopy. The secondary structure of the nanotubes is characterized by FT-IR, fluorescence spectroscopy and UV-Visible spectroscopy, which indicate the important role of aromatic 7r-Tr stacking interactions between phenylalanine residues in driving/3-sheet self-assembly. The electrochemical results showed that the Fc-KLVFF exhibits a pair of well-defined redox waves at oxidation potential （En） of 0.626 V and reduction potential （Ec） of 0.544 V, respectively, and the ratio of Ipa/Ipc is 1.08. Finally, the model for the self-assembly of Fc-KLVFF is proposed.