作者:T. Schrader、P. Rzepecki、M. Wehner、O. Molt、R. Zadmard、K. Harms
DOI:10.1055/s-2003-41031
日期:——
A general concept for the stabilization of β-sheetsby designed artificial ligands is introduced. The ligands have twokey features: they contain acylated 3-aminopyrazoles with a DAD hydrogenbond donor and acceptor pattern, and they were synthesized as oligomersin order to multiply their hydrogen bond interactions with peptidesin the β-sheet conformation. Dimeric aminopyrazoles wereaccessible by reaction of the N1-Boc-protectedaminopyrazole derivative 1 with severalacid dichlorides followed by a standard deprotection procedure withtrifluoroacetic acid. For the oligomers, N1-PMBprotection of new pyrazole amino acids followed by an iterativeextension protocol with peptide coupling using PyClop or Mukaiyama’sreagent led to the target compounds. All protecting groups weresubsequently removed in a final deprotection step with warm trifluoroaceticacid. Two dimeric key compounds 3b and 3f were examined by NMR at various temperatures,in NOESY experiments as well as by X-ray crystallography in orderto elucidate their conformational preference in solution and thesolid state. The emerging picture was the same for all methods: bothligands adopt a flat conformation with a high degree of pre-orientationand the correct DAD pattern for optimal interaction with peptidesin their extended conformation. Aggregation assays with the Prionprotein and the Alzheimer’s peptide Aβ (1-40)show highly promising results for some of the dimeric and oligomericligands at very low concentrations.
本文介绍了利用设计的人工配体稳定δ-片材的一般概念。这些配体有两个主要特征:它们含有酰化的 3-氨基吡唑,具有 DAD 氢键供体和受体模式;它们被合成为低聚物,以增加它们与δ-片构象中的肽的氢键相互作用。二聚氨基吡唑可通过 N1-Boc 保护的氨基吡唑衍生物 1 与几种二氯酸反应,然后用三氟乙酸进行标准脱保护处理而获得。对于低聚物,对新的吡唑氨基酸进行 N1-PMB 保护,然后使用 PyClop 或 Mukaiyama 试剂与肽偶联进行迭代扩展,最终得到目标化合物。随后,所有的保护基团都在最后一步用温三氟乙酸进行脱保护。对两个二聚关键化合物 3b 和 3f 进行了不同温度下的核磁共振、NOESY 实验和 X 射线晶体学研究,以阐明它们在溶液和固体状态下的构象偏好。所有方法得出的结果都是一样的:两种配体都采用具有高度预取向性的扁平构象和正确的 DAD 模式,以便与扩展构象中的肽发生最佳相互作用。用朊病毒蛋白和阿尔茨海默氏症肽 Aβ (1-40) 进行的聚合试验表明,一些二聚体和寡聚体配体在极低浓度下就能产生很好的效果。