Fig. 1: Binding spectra of sterols with CYP5122A1 and CYP51.

Purified recombinant CYP5122A1 (A) and CYP51 (B) (in the oxidized ferric form) were incubated with an increasing amount of sterol ligands and difference spectra were recorded over a reference sample that only contained protein and buffer. Dissociation constant (Kd) was derived by fitting the equation ΔA = ΔAmax[L]/(Kd + [L]) to the peak-to-trough absorbance difference (ΔA) versus the ligand concentration ([L]) curve, where ΔAmax is the maximal amplitude of the spectral response.