抑制剂作用的人胰岛淀粉样肽热力学性质与聚集机制探究

Type II diabetes is a kind of disease which seriously threaten human being's health. Human islet amyloid polypetide(hIAPP) may transfer its conformation from normal secondary structure to an abnormal β-sheet component, and induce the peptide to selfaggregate and further fibrillate. It results in the damage of cell membrane, the increasing of membrance permeability and oxidative stress, and the dysfunction of islet β-cell which is a crucial factor in the pathogenic mechanism of type II diabets. Therefore, inhibiting the aggregation of hIAPP is of great value to treat this kind of disease. Metal complexes based on ruthenium and vanadium cations are widely used as potential antiancer and antidiabetic drugs due to their lower cytotoxicity. However, those compounds are rarely reported to inhibit the aggregation of hIAPP. In this project, we'd like to investigate the thermodynamic properties of the interactions between hIAPP and metal complexes base on ruthenium and vanadium cations, by different biophysical methods such as differencial scanning calorimetry, fluorescence spectroscopy, ESI-MS, isothermal titration calorimetry and detection of related cytotoxicity. The studies will explain the different binding affinity and binding mode between them, explore the effects of various ligands on the thermal stability and selfaggregation kinetics of hIAPP, and reveal the rules of metal inhibitors in their structure-activity relationship. It may also indicate the inhibition mechanism of metal complexes on peptide fibrillation. The work will be significant for designing and developing potential metallodrugs against type II diabetes.

II型糖尿病是严重威胁人类健康的一种疾病，人胰岛淀粉样多肽(hIAPP)通过二级结构改变产生β-折叠构象并进一步聚集纤维化，导致细胞膜破损、细胞膜通透性增大与氧化压力，以及胰岛β细胞功能丧失，是II型糖尿病重要的致病因素，因而抑制hIAPP聚集对II型糖尿病的治疗意义重大。金属钌和钒的配合物因其较低的细胞毒性已被用作潜在的抗癌及降糖药物，但它们对淀粉样多肽的聚集抑制鲜有报道。本课题组拟通过差示扫描量热、荧光光谱、电喷雾质谱、等温滴定量热法、细胞毒性检测等手段研究不同构型钌、钒金属配合物与hIAPP相互作用的热力学性质，揭示金属配合物与hIAPP的结合亲和性与结合方式，探索不同构型配体对hIAPP自身聚集热稳定性及动力学行为的影响，形成对hIAPP金属抑制剂结构功能关系的规律性认识，阐明金属配合物对多肽聚集纤维化的抑制机理，研究工作对设计和发展针对II型糖尿病的潜在金属药物具有重要意义。

人胰岛淀粉样肽(hIAPP)与II型糖尿病的致病机制紧密相关，它可以通过自聚集产生多肽二级结构的改变，并导致淀粉样沉积和细胞膜的破坏，从而引起胰岛beta细胞的生物功能丧失，因而成为II 型糖尿病药物研究的重要靶点之一。本项目主要研究了一系列不同配体的钌、钒配合物对hIAPP聚集行为的影响及其相互作用的热力学性质。数据表明金属配合物比单独配体对多肽聚集有更好的聚集抑制作用，能将多肽聚集体由微米级颗粒分散为纳米级颗粒；这些潜在金属配合物与多肽的结合热力学性质研究表明，结合过程为自发过程，并以焓驱动性为主，配合物与多肽的结合主要由疏水作用和金属配位作用贡献。配合物还可有效降低由多肽聚集引发的胰岛INS-1细胞毒性。比较了金属配合物对hIAPP及其多肽片段的相互作用机制和抑制作用的差异，并进一步探索了一些金、钛配合物对多肽聚集的抑制作用。本项目按照研究计划顺利完成，研究成果包括已发表的学术论文十四篇，申请国家发明专利两项，会议报告七篇，达到了预期的研究目的。