澱粉樣纖維蛋白與有機抑制物相互作用力之探討

液態核磁共振技術目前已成為研究生物分子的有力工具，本篇論文將利用液態核磁共振技術來探討澱粉樣纖維蛋白與有機抑制物之間的作用力。澱粉樣纖維蛋白與許多人類的退化性疾病都有所相關，例如阿茲海默症及帕金森氏症。其中尤其是造成阿茲海默症的beta amyloid在腦中所形成的沉積物，目前普遍認為要治癒阿茲海默症必須從這類沉積物著手。在許多科學家的努力之下，目前這類型的研究正在持續進行，也已發展出許多抑制物來防止beta amyloid從單體轉變成堆積的狀態。在這方面，有研究指出有機物SLOH對於抑制Ab1-40多肽體堆疊有非常顯著的效果。為了探討Ab1-40與SLOH的分子間作用力，本論文利用標準的液態核磁共振技術來研究Ab1-40單體及SLOH，還有兩者的混合物。在光譜分析方面的工作是採用Robert Tycko教授所發展出來的Monte Carlo方法(MCASSIGN)來為Ab1-40的NMR光譜做循序判定。研究結果顯示MCASSIGN軟體對於幫助胺基酸種類的判定以及訊號重疊的問題有很大的助益。藉由觀察加入SLOH前後之液態核磁共振光譜，我們發現Ab1-40的骨架結構大部分都不會因為添加SLOH而有所改變，有部分訊號會隨著加入SLOH的量增加而造成強度有明顯的改變。觀察光譜變化並且配合循序判定的結果，確認作用力產生的位置大約是在第八至第十八個殘基以及第二十五至二十八個殘基之間，根據這些胺基酸的特性，加上SLOH的結構同時有極性及非極性部分，我們推論SLOH與Ab1-40的相互作用力並不具有專一性，但對多肽的序列仍有一定的選擇性，以上的發現對於改良SLOH結構應有相當的幫助。

關鍵字

澱粉樣纖維蛋白；有機抑制物

並列摘要

Amyloid-forming proteins are associated with many human neurodegenerative diseases. In particular, aggregates or fibrils formed by Ab1-40 have been considered as therapeutic target for Alzheimer‘s disease. There has been an on-going effort to develop inhibitors to prevent monomers of Ab1-40 from aggregating. In this regard, it has been shown that SLOH is quite effective in suppressing the fibril formation of Ab1-40 polypeptides. To probe the intermolecular interaction between SLOH and Ab1-40, we employ standard solution-state NMR methods to study the monomer of Ab1-40, SLOH, and in the mixture with different molar ratios. The spectral assignment has been carried out using the Monte Carlo approach developed in Tycko’s lab (MCASSIGN). In this study, we prove that MCASSIGN is useful for sequential assignment of TOCSY and NOESY spectra. The backbone structure of Ab1-40 remains largely intact upon the addition of SLOH. Minor perturbations in chemical shifts have been observed, and the intensities of some peaks have considerable changes. On the basis of these observations, we conclude that the interaction between Ab1-40 and SLOH occurs at residues S8 to V18 and G25 to K28. Based on the properties of these amino acids and the structure of SLOH, we believe that the interaction between Ab1-40 and SLOH is not specific, but it still has certain selectivity towards the positively charged regions of Ab1-40.

並列關鍵字

Beta amyloid ； Organic inhibitor

參考文獻

[1] J.D. Sipe, A.S. Cohen, Review: History of the amyloid fibril, J. Struct. Biol. 130 (2000) 88–98.

[2] F. Chiti, C.M. Dobson, Protein misfolding, functional amyloid, and human disease, in: Annual Review of Biochemistry, Annual Reviews, Palo Alto, 2006: pp. 333–366.

[3] H. Puchtler, F. Sweat, M. Levine, On Binding of Congo Red by Amyloid, J. Histochem. Cytochem. 10 (1962) 355–364.

[4] L.C. Serpell, M. Benson, J.J. Liepnieks, P.E. Fraser, Structural analyses of fibrinogen amyloid fibrils, Amyloid-J. Protein Fold. Disord. 14 (2007) 199–203.

[5] J.L. Jimenez, J.L. Guijarro, E. Orlova, J. Zurdo, C.M. Dobson, M. Sunde, et al., Cryo-electron microscopy structure of an SH3 amyloid fibril and model of the molecular packing, Embo J. 18 (1999) 815–821.

國際替代計量

澱粉樣纖維蛋白與有機抑制物相互作用力之探討

全文下載

主題瀏覽