Figure 3.

Interactions of ANF with CYP3A4, CYP3A4(C58,C64), and their BADAN-modified derivatives monitored by the substrate-induced spin shift. A series of absorbance spectra of 1 µM heme protein were recorded at different ANF concentrations, and the percent of high spin content versus the substrate concentration was plotted. The lines show fitting of these data sets to the Hill equation with S₅₀ = 3.7 and n = 2.2 for CYP3A4 (a, circles, solid line), S₅₀= 4.2 and n = 1.7 for CYP3A4-BADAN (a, squares, dashed line), S₅₀= 2.9 and n = 2.0 for CYP3A4(C58,C64) (b, circles, solid line), and S₅₀ = 2.0 and n = 1.6 for CYP3A4(C58,C64)-BADAN (b, squares, dashed line). Experimental conditions as indicated in Figure 1.