Synthesis and structural properties of cyclic peptides incorporating novel non-reducible cystine mimics

包含新型不可还原胱氨酸模拟物的环肽的合成和结构特性

• 批准号: 2243344
• 金额: --
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2243344
• 关键词: Synthesis; structural; properties; cyclic; peptides

The aim of this project is to develop a range of bioactive cyclic peptides incorporating lanthionine and cystathione as metabolically stable, non-reducible replacements for disulfide linkages. By studying the conformational and biological properties of these disulfide replacements, we aim to understand how they could best be used as tools to study and alter biological processes, and to evaluate them as possible leads in drug discovery programmes.The resurgence of interest in cyclic peptides has been driven by their potency and selectivity when binding to therapeutically relevant targets, such as receptors, protein-protein interactions (PPI) and transcription factors, which are difficult to address with small molecule therapeutics or with biologics. The conventional approach to applying a conformational constraint to a peptide lead is to cyclise by introducing a disulfide bridge between two Cys residues. However, such linkages are reduced in vivo and are not metabolically stable; thus there is considerable interest in making cyclic peptides which have a thioether linkage (from incorporation of lanthionine or cystathionine) instead. Indeed, CRB are frequently asked by their clients to provide cyclic peptide analogues containing these unnatural linkages for early stage drug discovery programmes.The Tabor group have pioneered a solid-phase peptide synthesis (SPPS) approach to lanthionine- containing peptides.1,2,3 This involves the stereoselective synthesis of orthogonally protected lanthonine, the incorporation of this residue in a linear peptide, selective removal of the protecting groups on the w-amino acid moiety, cyclisation on-resin and chain extension. This is now the method used by groups worldwide for the chemical synthesis of lantibiotics, an emerging class of antimicrobial peptides. However, this method has not yet been widely used to prepare non-reducible, conformationally constrained analogues of other biologically active peptides,3,4,5 and the effects of introducing this bridge on the conformation and biological properties of these peptides is also not well understood. This project will therefore focus on applying the SPPS approach to synthesising thioether bridged conformationally constrained analogues of key peptides involved in receptor binding. In order to understand the effect that these disulphide bond replacements have on the peptide conformation, and in particular to determine whether the peptides can adopt the biologically active conformation, the structural properties of these peptides will be analysed by NMR, using NAMFIS- analysis,6 in collaboration with Prof Mate Erdelyi (University of Uppsala). The student will also spend 3 - 4 months receiving training in this technique at Uppsala. Workplan:Year 1 Months 1 - 6 LIDo training courses (SysMIC, Bio-Industry). Small-scale synthesis of orthogonally protected lanthionine and cystathionine amino acid building blocks.Months 7 - 12 Synthesis of two analogues of vasopressin,7 one with with lanthionine and one with cystathionine replacements for the native disulfide bondYear 2 Months 13 - 18 NMR studies of cyclic peptides: training in NAMFIS technique (University of Uppsala, Sweden: Prof Mate Erdelyi)Months 19 - 24 CRB Placement 1 (Section 5)Year 3 Months 25 - 32 Synthesis of all variants thioether bridge lengths and a-stereochemistry of vasopressin,7 somatostatin5 and of the client peptide synthesised in Placement 1: NMR analysis, biological evaluation (calcium flux FLIPR assay).Months 33 - 38 CRB Placement 2 (Section 5)Year 4 Months 39 - 42 NMR analysis of peptides synthesised in Placement 2 Months 43 - 48 Thesis writing

该项目的目的是开发一系列含有兰硫氨酸和半胱硫酮的生物活性环肽，作为二硫键代谢稳定、不可还原的替代品。通过研究这些二硫键取代物的构象和生物学性质，我们旨在了解它们如何最好地用作研究和改变生物过程的工具，并评估它们作为药物发现计划中可能的线索的作用。环肽在与治疗相关的靶点结合时的效力和选择性推动了人们对环肽的兴趣，如受体、蛋白质相互作用(PPI)和转录因子，这些都是小分子治疗学或生物学难以解决的。传统的方法是通过在两个半胱氨酸残基之间引入二硫键来对多肽先导进行构象约束。然而，这种连接在体内被减少，并且在代谢上不稳定；因此，人们有相当大的兴趣来制备具有硫醚连接的环肽(通过掺入兰硫氨酸或胱硫氨酸)。事实上，CRB的客户经常要求CRB提供包含这些不自然连接的环肽类似物用于早期药物发现计划。Tabor团队开创了含有羊硫氨酸的固相肽合成(SPPS)方法。1，2，3这涉及到正交保护的羊毛氨酸的立体选择性合成，将该残基加入到线性多肽中，选择性地去除w-氨基酸部分上的保护基团，在树脂上环化和扩链。这是现在世界各地的团体用来化学合成抗生素的方法，抗生素是一种新兴的抗菌肽。然而，这种方法还没有被广泛用于制备其他生物活性多肽3，4，5的不可还原、构象受限的类似物，而且引入这种桥对这些多肽的构象和生物学性质的影响也不是很清楚。因此，本项目将集中于应用SPPS方法来合成与受体结合有关的关键多肽的硫醚桥连构象受限类似物。为了了解这些二硫键取代对多肽构象的影响，特别是确定多肽是否可以采用具有生物活性的构象，将使用NAMFIS分析，6与乌普萨拉大学的Mate Erdelyi教授合作，通过核磁共振分析这些多肽的结构性质。学生还将在乌普萨拉接受3-4个月的这项技术培训。工作计划：第1年1个月至6个LIDO培训班(SysMIC、生物工业)。小规模合成正交保护的羊硫氨酸和半胱硫氨酸氨基酸构建块。7-12个月合成两个加压素类似物，7个与兰硫氨酸和一个与半胱硫氨酸取代的天然二硫键环肽的核磁共振研究：NAMFIS技术培训(瑞典乌普萨拉大学：Mate Erdelyi教授)19-24个月CRB放置1(第5节)3个月25-32年所有加压素的硫醚桥长度和a-立体化学的合成，7生长抑素5和在放置中合成的客户肽：核磁共振分析，7生长抑素5和客户肽1：核磁共振分析，生物学评价(钙通量FLIPR分析).33-38个月CRB植入2(第5篇)4个月39-42个月植入中合成多肽的核磁共振分析43-48篇论文写作