理學院: 化學研究所指導教授: 陳平潘彥瑾PAN, YAN-JINYAN-JINPAN2017-03-022018-07-102017-03-022018-07-102016http://ntur.lib.ntu.edu.tw//handle/246246/271903離子對作用力是穩定蛋白質重要的作用力之一，穩定離子對作用力主要由帶相反電荷的氨基酸所形成，例如:Arg/Lys and Asp/Glu。為了深入了解離子對作用力的形成以及它們在蛋白質結構中扮演的腳色，我們設計了一個β-hairpin的胜肽系統，測量離子對作用力對β-hairpin結構穩定性的影響。在此，我們研究了側鏈長度對cross-strand diagonal離子對作用力的影響。胜肽透過固相合成，並用反相HPLC純化。根據二維核磁共振光譜(TOCSY，ROESY和DQF-COSY)，確認胜肽所形成的β-hairpin結構並計算出β-hairpin摺疊比例以及自由能。結果顯示β-hairpin的穩定性: HPDAadDap> HPDGluDab∼HPDAadDab>HPDGluDap> HPDAspDab>HPDAspDap。即側鏈較長的胺基酸離子對，形成最穩定的β-hairpin 結構。 雙螺旋結構是在自然界中常發現的結構單元，對於其序列和穩定性之間的關係有相當了解，因此常被用來做為研究蛋白質二級和三級作用力的理想系統。許多研究顯示將含氟氨基酸(疏水胺基酸的類似物)併入蛋白質疏水核心的結構中， 可穩定此蛋白質結構。這種穩定通常被稱為fluoro-stabilization effect。為了進一步了解fluoro-stabilization effect對蛋白質穩定性的影響，我們將含氟氨基酸併入一雙螺旋結構胜肽的疏水核心結構中,此一胜肽是根據轉錄因子GCN4設計的序列。Ion pairing interactions play important roles in protein structure stability. Stabilizing ion pairing interactions are formed between two oppositely charged residues such as Arg/Lys and Asp/Glu. To gain insight into ion pairing interactions and their potential roles in protein structure, we have designed a β-hairpin peptide system, allowing the measurement of the stability effects of individual charged residues and ion pairing interactions. Herein, we study the effect of side chain length on cross-strand diagonal ion pairing interactions. Peptides were synthesized by solid phase methods and purified by reverse phase HPLC. The sequence specific assignments were obtained based on TOCSY, ROESY, and DQF-COSY spectra. The β-hairpin structures were confirmed by chemical shift deviation, 3JHNα coupling constants, and NOE signals. The fraction folded and ΔGfold of the peptides were derived by comparing the chemical shifts with the folded and unfolded reference peptides. The stability of the peptides followed the trend : HPDAadDab ~ HPDAadDap > HPDGluDab ~ HPDGluDap > HPDAspDab ~ HPDAspDap. The results indicate that pairing the longer side chains provides the most stable β-hairpin. Coiled coil is a common motif found in nature. These motifs are ideal models for the study of protein secondary and teriary inteactions because the relationship between sequence and stability are well-understood. Incorporation of fluorinated amino acid residues into coiled coil peptides can stabilize coiled coils. This stabilization has been referred to as the fluoro-stabilization effect. To further understand the fluoro-stabilization effect in proteins, peptides based on the leucine zipper region of the yeast transcription factor GCN4 was designed and fluorinated amino acids were incorporated at the hydrophobic positions.4539647 bytesapplication/pdf論文公開時間: 2019/8/26論文使用權限: 同意有償授權(權利金給回饋學校)離子對作用diagonal 作用力β-hairpin捲曲螺旋含氟胺基酸GCN4Ion pairing interactionsdiagonal interactionscoiled coilfluorinated amino acidsthesis10.6342/NTU201603038http://ntur.lib.ntu.edu.tw/bitstream/246246/271903/1/ntu-105-R03223211-1.pdf