本實驗以雙偏極化干涉術(DPI)量測鐵離子與乳鐵蛋白結合或是解離時所引發的蛋白質構形、厚度、密度、表面濃度(質量)等變化，得到當鐵離子與乳鐵蛋白進行解離反應時，DPI晶片上的乳鐵蛋白的構形變化為厚度減少、密度增加；當鐵離子與乳鐵蛋白進行結合反應時，則為厚度增加、密度減少，此結果可能與乳鐵蛋白固定在DPI晶片表面時屬於亂相固定有關。本實驗由乳鐵蛋白中解離出鐵離子的方法為外加pH為2.2的酸性緩衝液(Glycine-HCl buffer)；而與乳鐵蛋白結合的鐵離子則採用氯化鐵(FeCl3)水溶液。本實驗更提出乳鐵蛋白構形變化程度與所加入之鐵離子濃度倍數的關係，當加入的鐵離子之濃度增加時，乳鐵蛋白其厚度次序增加，但密度次序減少，且當加入鐵離子濃度倍數達到20-50倍(48.6~121.5 μM)時，鐵離子與乳鐵蛋白之間結合會有飽和現象。 In this study, we use the dual polarization interfereometry (DPI) to measure the difference of lactoferrin protein after or before treated by iron ion. The parameters of conformation change of lactoferrin, surface concentration, thickness change and density on chip can be determined by Maxwell methods. We also show the relationship of conformation change of lactoferrin proteins with the iron ion concentrations. When iron ion is dissociated from lactoferrin, conformation change of lactoferrin on DPI chip is thickness decrease and density increase, and when iron ion is associated from lactoferrin, conformation change of lactoferrin on DPI chip is thickness increase and density decrease. This results may be correlated with non-specific immobilization. When iron ion concentrations is 48.6~121.5 μM, the association between iron ion and lactoferrin will be saturated. The dynamic parameters of lactoferrin bind to iron ion can be determined by the molecule dynamic model.
