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Title: | 氧化還原對之於類澱粉蛋白質聚集行為的影響 Effect of Redox Pair on Fibrillogenesis of Amyloid Proteins |
Authors: | Shang-Wei Chou 周上偉 |
Advisor: | 王勝仕 |
Keyword: | 溶菌酶,類澱粉蛋白,雙硫鍵,榖胱甘肽, lysozyme,amyloid protein,disulfide bond,glutathione, |
Publication Year : | 2006 |
Degree: | 碩士 |
Abstract: | 至少二十種人類蛋白質可以產生類澱粉沉積的纖維構造而造成類澱粉症。於發病的過程中,此類蛋白質轉換成富有β-sheet 之構形,
並形成纖維狀結構(fibril),然後自我聚集成大量糾結體(aggregate), 此糾結體堆積於身體組織周圍導致人體病變。迄今,類澱粉蛋白誘發 疾病之真正機制尚未完全清楚。 本研究利用與雙硫鍵有關的榖胱甘肽(oxidized glutathione/reduced glutathione,GSSG/GSH)氧化還原對,並調整不 同的濃度比例,來測試對於實驗室中常用的兩種類澱粉蛋白之聚集行 為的影響,分別是雞蛋白溶菌酶(hen egg white lysozyme)和類澱粉 β蛋白(β-amyloid,簡稱Aβ)。我們使用了多種蛋白質的分析方法, 結果發現:新鮮配置溶菌酶類澱粉纖維溶液時添加2 mM GSH 具有 抑制類澱粉纖維生成的效果,抑制比例達90%,而添加2 mM GSSG 則不影響類澱粉纖維的聚集行為;混雜了GSH、GSSG 的溶菌酶樣品 中,GSSG 也不會影響GSH 的抑制作用;另外以GSH 抑制溶菌酶類 澱粉纖維成長的關鍵時期是在延遲階段的前半段(六天以前)。相反 地添加不同比例的GSSG/GSH 對於類澱粉β蛋白聚集體的抑制有限, 這是因為Aβ不含半胱胺酸,無法形成雙硫鍵,也無法和GSH 有交互 作用。本研究之成果不但有助於解釋類澱粉蛋白聚集行為的機制,並 且進一步了解類澱粉症的真相。 At least twenty different human proteins can fold abnormally resulting in the formation of amyloid fibrils and accompanying pathologies. These proteins have little sequence homology; however, they are capable of self-assembling into stable fibrils with a characteristic cross β pleated sheet secondary structure. Although amyloid diseases have been the center of intense research, the role of amyloid protein and the toxicity mechanisms that mediate its biological responses remain rather elusive. The research presented here is aimed at examining the effect of relative distribution of the redox pair, the concentration ratio between reduced and oxidized forms of glutathiones ([GSSG]/[GSH]), in buffer solution on the in vitro fibrillogenesis/aggregation of two model proteins, lysozyme and β-amyloid. Using various spectroscopic and analytical methods, our results demonstrated that around 90% of lysozyme fibril formation was inhibited in the presence of pure GSH at 2 mM while no anti-aggregating activity was observed with only GSSG at 2 mM. Moreover, the presence of GSSG did not seem to affect the inhibitory potency possessed by GSH when lysozyme was incubated with both GSSG and GSH. Our results also suggested that the inhibitory activity of GSH was effective when it was added within 6 days after the initiation of process. Much less inhibitory effect against fibril formation of Aβ was found in comparison with lysozyme. We believe that the outcome from this work will enable us, not only to comprehend the mechanism(s) of amyloid protein self-assembly, but also to aid in designing potential targets for amyloidosis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/32764 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 化學工程學系 |
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