| Item type |
学位論文 / Thesis or Dissertation(1) |
| 公開日 |
2010-02-22 |
| タイトル |
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タイトル |
Structural Studies of Amyloid Fibril of β2-Microglobulin: Application of IR Micro-spectroscopy |
| タイトル |
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タイトル |
Structural Studies of Amyloid Fibril of β2-Microglobulin: Application of IR Micro-spectroscopy |
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言語 |
en |
| 言語 |
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言語 |
eng |
| 資源タイプ |
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資源タイプ識別子 |
http://purl.org/coar/resource_type/c_46ec |
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資源タイプ |
thesis |
| 著者名 |
呂, 明
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| フリガナ |
ルミン
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| 著者 |
LU, Ming
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| 学位授与機関 |
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学位授与機関名 |
総合研究大学院大学 |
| 学位名 |
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学位名 |
博士（理学） |
| 学位記番号 |
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内容記述タイプ |
Other |
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内容記述 |
総研大甲第1015号 |
| 研究科 |
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値 |
先導科学研究科 |
| 専攻 |
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値 |
22 光科学専攻 |
| 学位授与年月日 |
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学位授与年月日 |
2006-09-29 |
| 学位授与年度 |
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値 |
2006 |
| 要旨 |
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内容記述タイプ |
Other |
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内容記述 |
Amyloid fibril has been found more than one hundred years ago（1854）in relation to several diseases．<br />It is an aggregation of proteins and/or peptides. It has attracted multiple interests from clinical study and<br />fundamental research. Because it is possible that partially denatured protein in amyloid fiblil escapes ftom<br />the cellular quality control and propagates by itself, the amyloid filbril is expected to be dangerous on<br /> clinical studies of several diseases. Such a character is also in the field of structural biology <br />with regards to self-assembly of macromolecules and protein folding.<br /> To date，much effort has been paid on the protein structure in an amyloid fibril，because of importance<br />for understanding the mechanism of protein folding and fibril formation. However，it is still a challenging<br />issue to determine the whole protein structure in the fibril．<br /> Another approach on this matter is to limit a scope. For example, one of the important aspects of the<br />fibril is a property to replicate by itself．In this case，a nature of intermolecular interactions would be an<br />indispensable information to understand what it is. As another example，it is of<br /> interest to know why the morphology of amyloid fibril is unique and exhibit similar dimension to each<br />other regardless of precursor proteins．In this case，a width of β-sheet core（as a common feature）should be<br />verified and such a factor should be discussed in relation to the dimension of the aggregation. Thus，partial<br />character of the structure may give a hint to explain several properties of the amyloid fibril. <br /> In this thesis, an amyloid fibril of β<small>2</small>-microglobulin(β<small>2</small>m),which is related to the dialysis-related<br /> amyloidosis，has been treated. IR spectroscopy and IR microscope is adopted as main technique. Truncated<br /> peptide fragment of b2m is ehosen as a probe to search the structural information of the interacting<br />segment.<br /> My aims at this point. First，a novel procedure is applied to clarify the structure of the interacting<br />segment of β<small>2</small>m amyloid fibril（fA[β<small>2</small>m]）by using IR spectroscopy. Even though the structural information<br />brought from IR spectroscopy is rather obscure than those of others including X-ray<br />diffraction or NMR spectroscopy, it brings practically essential information when it is applied in an<br />appropriate way．Mechanical structure will be clarified．<br /> Second aim of my thesis is the elucidation of chemical property of the interacting segment. For this<br />purpose，several fragment peptides derived from the sequence of β<small>2</small>m is examined．fibrilization efficiency<br />and the structure are discussed under, various pH conditions，and the experimental results will be discussed<br />in terms of the pH dependence of side chains and terminal charges<br /> This thesis contains four chapters：Chapter 1 reviews the general background of amyloid fibril，<br />character of β<small>2</small>m as well as its fibril state，the remaining problems in this field，and the purpose of this<br />thesis. Chapter 2 reports the novel protocol to search the position and to explore the conformation of the<br />interacting segment along the primary structure of β<small>2</small>m. In this chapter，the ＃21-31 fragment of β<small>2</small>m was<br />chosen as probe，and its fibril was prepared with the aid of the protein seeding property of the protein fiblil<br />（fA[＃21-31]-on-fA[β<small>2</small>m]）．The formation of this species was detected by ThT fluorescence method．<br />Possibility of spontaneous fibril formation of the #21-31 fragment was eliminated by designing the fibril<br /> preparation condition adequately. It is considered that attached tip that consists of<br />the flagment peptide molds the structure of the interacting segment of protein fibril. The result confirms<br />that one of the interacting segments is located at F22～V27 region with planar parallelβ－sheet structure.<br />This feature is different from the spontaneous fibril on which the energetically stable structure is<br />accompanied by moderate curl of β-sheet. This difference has been assigned to the planar β－sheet structure<br />of the interacting segment of fA [β<small>2</small>m] and the molding property of the amyloid fibril. Chapter 3 treats<br />amyloid formed by truncated peptides of β<small>2</small>mand consisted of two parts（I and Ⅱ）；I focuses on side chain<br />effect on fibril formation and II discusses the terminal charge effect on the structure．Both focuses on the<br />chemical character of interacting segment and the factors that appears as the critical interaction therein. In<br />this chapter，a series of fragment peptide of β<small>2</small>m around the interacting segment （e．g．around ＃21－31 region）<br />was chosen as sample，and the fibril formation property has been examined under various pH conditions．<br />The result has strongly indicated that the F22～V27 part possesses the inherent propensity to from the b-<br />sheet．In addition，it has been shown that（i）the aromatic-aromatic interaction is important<br />（ii）aliphatic－aliphatic interaction is not strong enough，and（iii）electrostatic interaction between charged<br />side chains depends upon the sign of charge with regard to the stabilization of fibril structure．Chapter4 is<br />the conclusion drawn out from this thesis．The nature of interacting segment of fA［β<small>2</small>m］will be discussed <br />by talking account of the mechanical and chemical properties deduced from this study. |
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値 |
有 |
要旨・審査要旨 (256.0 kB)
