FIGURE 7.

Critical concentrations of the peptide and of the lipid for vesicles containing different molar fractions of DOPG, X_PG = 0.0 (diamonds), 0.25 (circles), 0.50 (up triangles), 0.75 (down triangles), and 1.0 (squares). The solid and open symbols refer to P-to-L and L-to-P ITC experiments, respectively. The lines were calculated according to Eq. A8 with z_P = 5.1, K_50% = 20 mM⁻¹, f_Na = 0.15, ξ = 0.08 (X_PG > 0.25), K_50% = 10 mM⁻¹, f_Na = 0.13, ξ = 0.07 (X_PG = 0.25), and γ = 0.5 for 0 < X_PG ≤ 0.5, and γ = 1.0 for X_PG > 0.5. The line through the data for X_PG = 0.0 was drawn as a guide for the eyes. The arrows in the insert (with the same designations of the axes as in the main figure) show the concentration courses of the titration experiments for X_PG = 0.75. The critical peptide concentrations at which the absolute value of the differential heat decreases to 50% of its initial value are indicated by the symbols.