Figure 1.

(A) Chemical structure of bis-ANS. (B) Fluorescence titration of TF and TF389 with bis-ANS. A total of 1 μM TF (○) or TF389 (▵) was titrated with 0–50 μM bis-ANS in 0.1 M phosphate buffer (pH 7.5), 2 mM EDTA. The samples were excited at 390 nm, and emission at 490 nm was measured. The inset shows the Scatchard plot for the binding of bis-ANS to TF. (C) Job plot (Huang 1982) for binding of TF to bis-ANS at a total concentration of 50 μM at 25°C.