利用NMR 和CD 研究人類神經肽Y 的C 端衍生物hNPY(20-36)和
P34-hNPY(20-36)在30％三氟乙醇溶液中，在283 K 和310 K 下的變化。其結構的變化、自結合狀態和動力學行為的差異皆可能是由於單殘基突變，Q34→P34 所造成的。P34-hNPY(20-36)的最佳結構為形成一個α-螺旋片段在殘基25-30 及25-29 的位置，分別在283 K 和310 K 下。而hNPY(20-36)則會形成更長的α-螺旋片段，其位置在23-34 和24-35，分別在283K 和310 K。擴散實驗(DOSY)中顯示出P34-hNPY(20-36)在三氟乙醇溶液中會具有比hNPY(20-36)大的流體力學半徑。相較之下，從弛緩實驗得到此兩個胜肽片段在三氟乙醇溶液中具有相近的全相關時間。推測造成其結果可能為P34-hNPY(20-36)形成較大的寡聚體，使得P34-hNPY(20-36)的溶合作用較hNPY(20-36)小所造成。

Analog of human neuropeptide Y based on the region of C -terminus (hNPY(20-36)) and mutant at position 34 with proline were studied by NMR and CD in 30% trifluoroethanol (TFE) at 283K and 310K. The variation of structure, aggregation, and dynamics may be attributed to the single-residue mutation, Q34→P34. The optimal structure of mutated peptide consists of an α-helical segment with residues 25-30 and 25-29, at 283K and 310K, respectively. More extended α-helical segments were observed for hNPY(20-36), of which are ranged with residues 23-34 and 24-35, at 283K and 310K , respectively. Diffusion Ordered Spectroscopy (DOSY) experiment reveal P34-hNPY(20-36) forms larger aggregate than hNPY(20-36) in TFE aqueous solution. In contrast, the overall correlation times derived from relaxation data indicated similar size of both peptides in TFE. The result may be explained as a consequence of P34-hNPY(20-36) with more intermolecular interactions that increase the size of the “diffusion unit” which contains the molecule of interst and its surrounding, e.g., solvent or other solute molecules since the more extended structure.

第一章 緒論	1
1.1 NPY介紹	1
1.2 NPY在水溶液和與微胞結合的結構變化	2
1.3 研究目的	3
第二章 實驗原理	5
2.1 固相胜肽合成(Solid-Phase Peptide Synthesis, SPPS)	5
2.2 圓二色旋光光譜儀(Circular Dichroism Spectrometer, CD Spectrometer)	6
2.2.1 CD原理	6
2.2.2 多胜肽之二級結構CD光譜	10
2.3核磁共振(Nuclear magnetic resonance, NMR)	12
2.3.1 二維核磁共振原理(2D NMR)	18
2.4 XPLOR 原理	33
2.5無模型法則(Model-Free Approach)	34
第三章 實驗材料與方法	37
3.1  實驗材料	37
3.1.1 藥品	37
3.1.2 儀器	39
3.1.3 試劑配製	40
3.2 實驗方法	41
3.2.1 胜肽合成	42
3.2.2 胜肽純化與鑑定	43
3.2.3 Circular Dichroism	44
3.2.4 NMR	45
3.2.5 結構計算	46
3.2.6無模型法則(model-free approach)計算	47
第四章 結果與討論	50
4.1 CD光譜分析	50
4.2 NMR	52
4.2.1光譜判定	52
4.2.2 化學位移	76
4.2.3 DOSY光譜	78
4.3 結構計算	81
4.4 胜肽分子的動態行為	84
第五章 結論	88
第六章 參考資料	89

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