Figure 6.

Effect of the surface density of CYP3A4(C468)-BODIPY in proteoliposomes on the lifetime of fluorescence of the BODIPY probe. The preparations of the proteoliposomes were obtained by incubation of 1 µM CYP3A4-(C468)-BODIPY with various amounts of pre-formed liposomes for 1 hour in 0.1 M Na-HEPES buffer, 1 mM DTT, and 1 mM EDTA at 25 °C. Panel a: A series of normalized fluorescence decay traces (excitation an 405 nm, emission at 520 nm with the band with of 18 nm) obtained with L/P ratios of 100, 200, 400, 800, 1400 and 2000. All the curves of the set may be approximated by a sum of two exponents with characteristic times of 1.1 and 4.9 ns (ρ² > 0.95). The inset shows the traces obtained with L/P ratio of 100 (circles) and 2000 (triangles) in semi-logarithmic coordinates with fitting curves shown in solid lines.

b: Dependence of F_fast on the concentration of CYP3A4(C468)-BODIPY in the membrane of proteoliposomes. Data points represent the results of two independent experiments. The solid line illustrates the fitting of the data set with the equation for the equilibrium of bimolecular association (K_D = 1.35 ± 0.06 pmol/cm²).