FIGURE 4.

Reversible binding of CcO monitored by SPR. The cell is first filled with DDM/PBS. Into this solution, solubilized CcO is infused at points A and D, respectively, indicating the thickness increase due to binding of CcO. At point B the cell is rinsed with DDM/PBS containing 200 mM imidazole. The strong increase is due to change of refractive index. At point C the cell is flooded again with pure DDM/PBS changing the refractive index back to the initial value. The resulting reflectivity shows that almost complete desorption is achieved. When a new portion of solubilized CcO is infused at point D the increase in reflectivity indicates binding to be fully reversible.