Transfer of iron from DFP-Fe complexes to transferrin. DFP-Fe complexes (1:3 and 1:5 ratios; 50 μM Fe(III)) were mixed with apotransferrin aTf (50 μM) and incubated for 1.5 hours in a humidified 5% CO2 incubator at 37°C. At the conclusion of the reaction, 10 mM DTPA was added and the low–molecular weight material was removed by filtration as described in “Histone-CALG.” The tryptophan (trp) fluorescence at 280 nm excitation/306 nm emission (top graph) was obtained from the emission spectra (inset). The high–molecular weight fractions were diluted in HBS, pH 7.4, and the absorbance was read at 465nm (bottom graph). Data are given as means plus or minus SD of 3 independent experiments. The labels below the bars indicate the complexes tested and their concentrations. The values above the bars represent the percentage change in absorbance or fluorescence.