Figure 7. Normalized 9-AS fluorescence enhancement titrations comparing X4IRBP and the Arg¹⁰⁰⁵->Gln mutant

The binding of 9-AS to 1.33 µM of X4IRBP (filled symbols) and 0.92 µM of the Arg¹⁰⁰⁵->Gln mutant (open symbols) was monitored at 440 nm upon excitation at 360 nm. For X4IRBP, N = 0.87±0.12 and K_d = 0.51±0.09 µM. For Arg¹⁰⁰⁵->Gln, N = 5.00±0.29 and K_d = 0.05±0.07 µM. Nonnormalized data is shown as an insert.