Fig. 4. Substrate binding assay for wt AhbD and the AhbD variants. The binding of Fe-COPRO III to wt AhbD and the AhbD variants was followed by UV-visible absorption spectroscopy. Fe-COPRO III was mixed with either buffer or the indicated proteins and spectra were recorded (a) directly after mixing (0–100 s), after 270 s (270–370 s) and (b) after 24 h. The observed shift of the Soret band upon addition of AhbD is indicated. An UV-visible absorption spectrum of purified wt AhbD alone is shown in ESI Fig. A† for comparison.
