根據我們之前的研究顯示β-bungarotoxin B chain具有破壞脂質體細胞膜的能力，有鑑於抗菌胜肽其抗菌作用和破膜活性有關，因此在本論文中研究B chain的破膜能力與抗菌活性間的關係。在抗菌實驗中發現B chain具有抑制Escherichia coli (革蘭氏陰性菌)生長的效果，但對於Staphylococcus aureus (革蘭氏陽性菌)卻沒有顯著抑制效果。藉由EDTA干擾E. coli細胞壁lipopolysaccharide (LPS)層的穩定性與rifampin干擾S. aureus的lipoteichoic acid (LTA)的合成，發現可以增加B chain對於E. coli與S. aureus的抗菌能力。B chain可以破壞模擬細菌細胞膜lipid組成的脂質體，造成內含螢光物質滲出和脂質體融合現象產生，但此一活性會受LPS與LTA所抑制，並且LTA抑制β-bungarotoxin B chain破膜活性與融合活性的能力比LPS強，但B chain對LPS及LTA的親和力，並無顯著差異，顯示LPS與LTA對B chain活性的差異性作用與親和力無關。以Circular dichroism分析B chain結構變化，發現LPS與LTA與B chain結合可誘導改變B chain的二級結構。綜合以上實驗結果顯示B chain的抗菌活性與其破膜和脂質體融合活性有相關性，並且LPS和LTA誘導B chain結構的變化，影響B chain的破膜，脂質體融合及抗菌活性。

Our previous studies showed that recombinant β-bungarotoxin B chain exhibited membrane-damaging activity. Given that membrane-damaging activity is crucial for bactericidal effect of antibacterial peptide, the causal relationship between membrane-damaging activity and antibacterial action of B chain was performed in this study. β-bungarotoxin B chain exhibited a growth inhibition on Escherichia coli (Gram-negative bacteria), but marginally displayed bactericidal effect on Staphylococcus aureus (Gram-positive bacteria). Destabilization of lipopolysaccharide (LPS) layer and inhibition of lipoteichoic acid (LTA) biosynthesis on cell wall increased bactericidal effect of B chain on E. coli and S. aureus. B chain induced leakage and fusion of bacterial membrane-mimicking liposomes. Compared with LPS, LTA notably suppressed membrane-damaging activity and fusogenicity of B chain. B chain showed similar binding affinity with LPS and LTA. Circular dichroism measurement revealed that LPS- and LTA-binding differently induced conformational change of B chain. Taken together, our data indicate that antibacterial action of B chain is related to its ability to induce membrane permeability and fusogenicity, and suggest that LTA- and LPS- induced conformational change of B chain affect membrane-damaging activity, fusogenicity and antibacterial activity of B chain.

中文摘要........................................................i
Abstract........................................................ii
英文縮寫表.....................................................iii
目錄...........................................................1
一、緒論........................................................2
二、實驗材料與方法..............................................9
三、結果.......................................................22
四、討論.......................................................27
參考文獻......................................................31
圖表..........................................................40

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