Figure 3

Metal binding studied by Tb³⁺-FRET. (A) The fluorescence enhancement at 545 nm with increasing concentrations of Tb³⁺ in 5 μM of EEDDN in 20 mM PIPES, 10 mM KCl pH 6.8. (B) Determination of Tb³⁺ binding affinity of EEDDN by analyzing the dependence of the fluorescent intensity change on Tb³⁺ concentration. The solid line is the fitted curve. (C) Decrease in fluorescence by the addition of La³⁺ into a fixed concentration of Tb³⁺ and EEDDN. This data was analyzed to obtain K_d for La³⁺.