Synthesis and characterisation of amyloid fibre motifs and mimetics participating in cooperative binding with serum amyloid p component.

参与与血清淀粉样蛋白 p 成分协同结合的淀粉样蛋白纤维基序和模拟物的合成和表征。

• 批准号: BB/H015809/1
• 金额: $ 10.61万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Training Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FH015809%2F1
• 关键词: Synthesis; characterisation; amyloid; fibre; motifs

The plasma glycoprotein, serum amyloid p component (SAP) binds to amyloid fibres wherever they are deposited in diseased tissues. More than twenty different proteins are known to form fibres. SAP does not bind to any of the proteins in their native state. Therefore the fibre recognition motif must arise from the structural transition that takes place during fibre formation. SAP may be involved in promoting fibre deposition and is known to stabilise fibres, protecting them against proteolytic attack and digestion by phagocytic cells. The interaction therefore appears to be a good target for amyloid clearing drugs. SAP is pentameric and each Mr 23500 subunit carries a double calcium site that is believed to be the amyloid recognition site. Small molecules such as phosphoethanolamine or D-proline bind to this site with modest affinity (Kd 20-40 micromolar) via their acidic components binding the calcium ions. The experimental drug CPHPC (Pepys et al Nature 2002) is a bivalent compound comprising two D-proline residues linked through their N termini via a six carbon aliphatic chain. This compound crosslinks pairs of SAP molecules forming a decameric complex where five drug molecules interact with ten SAP subunits. The cooperativity of this mode of binding enhances the affinity of the interaction by three orders (Kd 10 nano-molar). The resulting decamers of SAP are rapidly cleared by the liver in vivo but the compound has insuffient affinity to completely strip all SAP from fibre deposits. The aim of this project is to synthesise cyclic peptides carrying five D-proline arms on one face or ten D-proline arms distributed on both faces. The hypothesis is that these compounds should bind to SAP in a calcium dependent manner with enhanced cooperativity and high affinity, forming pentameric SAP with blocked fibre recognition sites or crosslinked decamers. Dr Broadbridge has extensive experience in preparing a wide spectrum of different cyclic peptides and this phase of the training will be carried out in his lab. at Peptide Protein Research Ltd. The binding of these products to SAP will be characterised by calorimetry at UCL and the potential mode of binding investigated by computer graphic investigation of SAP and the binding sites for D-proline head groups. The materials will be co-crystallised with SAP and the detailed structure of the interaction investigated by X-ray analysis. We will also investigate peptide sequences likely to be exposed on the surface of fibres. Structural studies on Abeta 1-42 and H/D exchange measurements on transthyretin and beta2 - microglobulin suggest likely regions that are exposed on fibres. The results of the work will provide new tools for investigating fibre formation and contribute to the design of more effective blockers of this process.

血浆糖蛋白，血清淀粉样蛋白P成分（SAP）与淀粉样蛋白纤维结合，无论它们沉积在患病组织中。已知有二十多种不同的蛋白质形成纤维。 SAP与其本地状态的任何蛋白质都没有结合。因此，纤维识别基序必须来自纤维形成过程中发生的结构过渡。 SAP可能参与促进纤维沉积，并已知可以稳定纤维，从而保护它们免受吞噬细胞的蛋白水解攻击和消化。因此，这种相互作用似乎是淀粉样蛋白清除药物的良好目标。 SAP是五聚体，每个MR 23500亚基都带有一个双钙位点，据信是淀粉样蛋白识别位点。小分子（例如磷酸乙醇胺或D-丙啉碱）通过其酸性成分结合钙离子的酸性成分与适度的亲和力（KD 20-40微摩尔）结合。实验性药物CPHPC（Pepys等人自然2002）是一种二价化合物，包括通过六个碳脂族链链通过其N末端连接的两个D-丙烯残基。这种复合的交联成对成对形成了dec缝复合物的SAP分子，其中五个药物分子与十个SAP亚基相互作用。这种结合模式的合作性增强了相互作用的亲和力，三个顺序（KD 10纳米摩尔）。肝脏在体内迅速清除了SAP的demate剂，但是该化合物的亲和力不足以完全从纤维沉积中剥离所有SAP。该项目的目的是合成在一张脸上携带五个d-丙烯臂的环状肽，或分布在两个脸上的十个d-丙烯臂。假设是，这些化合物应以钙的依赖性方式与SAP结合，并具有增强的合作性和高亲和力，从而形成五个纤维识别位点或交联的decamers的五型SAP。 Broadbridge博士在准备各种不同的环状肽方面拥有丰富的经验，并且将在他的实验室中进行训练的这一阶段。在肽蛋白研究有限公司处。这些产物与SAP的结合将以UCL的量热法为特征，以及通过对SAP的计算机图形研究和D-丙啉头组的结合位点研究的潜在结合模式。这些材料将与SAP共结晶，并通过X射线分析进行了研究的详细结构。我们还将研究可能暴露在纤维表面上的肽序列。关于ABETA 1-42和H/D交换测量的结构研究，对硫代蛋白和β2-微球蛋白表明可能在纤维上暴露的区域。该工作的结果将为研究纤维形成提供新的工具，并为该过程的更有效阻滞剂的设计做出贡献。