Fig 5. The affinity of Fe-cMB is attenuated for the FecB-E339S variant compared to WT-FecB.
A. CD shows that both WT-FecB (dashed black line) and FecB-E339S (solid blue line) have the same secondary structural elements. B & C. Comparison of representative fluorescent emission intensities at 335 nm after excitation at 280 nm with increasing concentrations of (B) Fe-cMB and (C) apo-cMB binding to WT-FecB (100 nM, black line) and FecB-E339S (100 nM, blue line). Curves were fit using Eq 1 and cMB affinities (Kd) are included for each titration for WT FecB.