• 作者： Wu, Ching-Fa; Chen, Wen-Yih; Liu, Hwai-Shen
• 中文摘要： 本研究探討在不同的pH值、鹽類濃度與溫度條件下,藉由Differential UV Spectroscopy方法,完成對固定化金屬離子與histidine與imidazole間結合常數之測定。實驗結果描述當改變鹽類濃度時,顯示鹼性物質與固定化金屬離子間之結合為雙作用力模式; 而當溶液pH值較imidazole group上氮原子之pKa值高時,解離之氮原子與形成螫合物之固定Cu(II)間,以電子配位力為主要之結合力。而溫度對於溶質與固定化金屬離子間結合力之影響,並無明顯之現象,無法利用溫度對於結合機制作進一步解釋。此外,本研究亦測量胜與固定化金屬離子間之結合力,除特定順序之二胜與三胜外,並有設計、合成不同順序之七胜,七胜中含有兩個histidine殘基,其中一個histidine殘基置於胺基端,並與另一個 histidine殘基間相隔不同數目之glycine殘基,實驗結果除定性描述histidine殘基的數目與位置對親和力之影響外,亦證明「金屬離子轉移」現象存在之可能性。本研究對於蛋白質與固定化金屬離子間之結合行為提供基本之資料。
• 英文摘要： An iminodiacetic acid derivative of poly(ethylene glycol) (PEG-IDA) with chelated Cu(II) was synthesized. The binding constants between immobilized Cu(II) with imidazole and histidine at various solution pH values, salt concentrations and temperatures were determined by differential UV spectrophotometer. The results indicate that a bimodel binding behavior of basic solute was observed by the study of the salt effect. However, at the pH value higher than pKa of the deprotonation of imidazole nitrogen, the formation of the coordinated compound is the dominant binding mechanism. There is no obvious effect of temperature on binding constants because of the complexity of binding mechanism. The binding behavior of several dipeptides and tripeptides with histidine at C- or N-terminal was also investigated and the results were explained by the "metal ion transfer" (MIT) hypothesis. Furthermore, the binding constants of synthetic heptapeptides with two histidine residues separated by different number of glycine residues were investigated to demonstrate the effect of histidine residues distance on the binding affinity. This study provides basic information of binding behavior of protein to immobilized metal ion.
• 中文關鍵字： 固定化金屬離子親和性; 結合常數; 紫外光示差光譜術; 組胺酸; 咪唑
• 英文關鍵字： Immobilized Metal Ion Affinity; Binding Constant; Uv Differential Spectroscopy; Histidine; Imidazole