Neves Ruben, Stephens Kailyn, Smith-Carpenter Jillian E
Department of Chemistry and Biochemistry, Fairfield University.
Department of Chemistry and Biochemistry, Fairfield University;
J Vis Exp. 2018 Aug 20(138):58135. doi: 10.3791/58135.
This report focuses on the synthesis of an N-terminus 1,2-dithiolane modified self-assembling peptide and the characterization of the resulting self-assembled supramolecular structures. The synthetic route takes advantage of solid-phase peptide synthesis with the on-resin coupling of the dithiolane precursor molecule, 3-(acetylthio)-2-(acetylthiomethyl)propanoic acid, and the microwave-assisted thioacetate deprotection of the peptide N-terminus before final cleavage from the resin to yield the 1,2-dithiolane modified peptide. After the high-performance liquid chromatography (HPLC) purification of the 1,2-dithiolane peptide, derived from the nucleating core of the Aβ peptide associated with Alzheimer's disease, the peptide is shown to self-assemble into cross-β amyloid fibers. Protocols to characterize the amyloid fibers by Fourier-transform infrared spectroscopy (FT-IR), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM) are presented. The methods of N-terminal modification with a 1,2-dithiolane moiety to well-characterized self-assembling peptides can now be explored as model systems to develop post-assembly modification strategies and explore dynamic covalent chemistry on supramolecular peptide nanofiber surfaces.
本报告重点关注N端1,2 - 二硫杂环戊烷修饰的自组装肽的合成以及所得自组装超分子结构的表征。合成路线利用固相肽合成，通过二硫杂环戊烷前体分子3 -（乙酰硫基）-2 -（乙酰硫基甲基）丙酸在树脂上的偶联，以及在从树脂上最终切割之前对肽N端进行微波辅助硫代乙酸酯脱保护，以得到1,2 - 二硫杂环戊烷修饰的肽。在对源自与阿尔茨海默病相关的Aβ肽成核核心的1,2 - 二硫杂环戊烷肽进行高效液相色谱（HPLC）纯化后，该肽显示能自组装成交叉β淀粉样纤维。还介绍了通过傅里叶变换红外光谱（FT - IR）、圆二色光谱（CD）和透射电子显微镜（TEM）对淀粉样纤维进行表征的方案。现在可以探索用1,2 - 二硫杂环戊烷部分对特征明确的自组装肽进行N端修饰的方法，作为开发组装后修饰策略和探索超分子肽纳米纤维表面动态共价化学的模型系统。
