探討天然小分子物質對蛋白質聚集之影響

Exploring the Effects of Naturally Occurring Molecules on the Protein Aggregation

劉冠男(Kuan-Nan Liu)

指導教授 ： 王勝仕

國立臺灣大學/工學院/化學工程學研究所/博士(2011年)

https://doi.org/10.6342/NTU.2011.02255

摘要

目前至少有27種，與人類有關之致死疾病(deadly human diseases)與其致病蛋白質錯誤折疊有關；雖然此類蛋白質其序列與功能皆無相似處，但與其相關之類澱粉症卻有相似之臨床、病理及生化特徵，即在人體內各患病組織產生結構與特性均相似之類澱粉纖維沉積。此外，研究亦已證實，即使不與人體疾病有關，蛋白質亦可利用不同環境條件誘使其產生類澱粉纖維結構；由此可知，即使是利用與疾病無關之蛋白質作為研究目標，透過研究其纖維化過程之特性及行為，依然可有助於了解如何抑制類澱粉蛋白之纖維化。本研究所選用之抑制物質皆為天然小分子，部分為常見於人體大腦內之灰質(gray / grey matter)中之磷脂質，薑黃素則為廣為人知之食品添加物及染色物質；兩者之角色均較人工合成之高分子物質、胜肽或是其他結構物，更易於取得，亦較易為人體吸收。
本研究之實驗結果可知，無論是磷脂質(己二酰甘油磷酸膽鹼(di-C6-PC)與庚二酰甘油磷酸膽鹼(di-C7-PC))或是多酚物質(薑黃素(curcumin))皆可明顯減少及延緩類澱粉蛋白(牛胰島素與雞蛋白溶菌酶)之纖維結構生成。另外，吾人更進一步發現利用兩細胞株(大白鼠嗜鉻性神經瘤細胞與人類神經瘤母細胞)，發現此兩蛋白質所形成之類澱粉纖維結構會對其產生明顯之毒殺性；且添加短鏈磷脂質與多酚物質皆可明顯保護兩細胞免於類澱粉纖維結構之毒殺。
除此之外，吾人續以不同溫度處理薑黃素，並發現部分溫度處理可產生較高比例之具抑制能力之薑黃素結構。利用紫外光 / 可見光光譜、電灑式質譜與核磁共振分析後得知，此一具抑制能力之結構極可能為薑黃素之雙體結構。
吾人亦藉由圓二色光譜分析與熱誘導開展分析，發現添加高濃度(4 mM)之磷脂質，與低溫(10

關鍵字

蛋白質聚集 ； 薑黃素 ； 二酰基磷脂醯膽鹼 ； 抑制劑 ； 細胞毒殺性

並列摘要

Abnormally folded proteins have been associated with at least twenty-seven debilitating and deadly human diseases. These diseases have distinct clinical, pathological, and biochemical characteristics, resulting in amyloid deposits with similar structures, and their corresponding precursor proteins have unrelated functions and share little sequence homology. Moreover, mounting evidence has suggested that the formation of amyloid fibrils is also possible for a variety of non-disease associated proteins. By taking advantage of this generic fibril-forming property, investigations of the amyloid fibrillation using disease-irrelevant proteins can thus aid in our understanding of possible inhibition of amyloid aggregation. The inhibitors that we used in this study include the predominant short-chain phospholipids that are present in the gray matter of the human brain and the polyphenol (e.g.: curcumin) that is widely used in food spicing and coloring. These naturally-occurring small molecules are accessible and easily absorbed by human body as comparison to the other synthesized polymers, peptides, and molecules.
Our results showed that all the short-chain phospholipids (di-C6-PC and di-C7-PC) and polyphenol (curcumin) are able to attenuate and retard the fibril formation of amyloid-forming proteins, such as bovine insulin and hen egg-white lysozyme. Also, we found that the fibrillar species of bovine insulin and hen egg-white lysozyme formed at acidic pH (pH 2.0) and elevated temperature (55

並列關鍵字

protein aggregation ； curcumin ； di-acyl-GPC ； inhibitor ； cytotoxicity

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